COATING INSPECTOR PROGRAM
Level 1 Practical
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Table of Contents
Inspection Test Plans | 16
Practical Math | 17
Measuring Environmental Conditions | 18
Soluble Salt Detection | 19
Measuring Surface Profile |
20
Day 3 Lab Worksheets
Measuring Film Thickness |
21
Holiday Detection |
22
Day 4 Lab Worksheets
Case Study Workshop
Elevated Water Tank Lab
Safety Awareness |
23
Steel Panel Lab
Chapter 16: Inspection Test Plans
Chapter 16:
Inspection Test Plans
16.1 Introduction
Learning Objectives
By the end of Chapter 16, students should be able to:
1. Describe the purpose and benefits of inspection test plans.
2. Review an inspection test plan and identify if any inconsistencies, omissions, or ambiguities are present.
Planning a Coating Project
Comprehensive planning by all stakeholders is
critical to the successful installation of a coating
system. The project’s specifier or engineer is
responsible for developing the project specification.
The specification writer must design the work to be
done and prepare a set of requirements that will
help ensure that the final coating product meets all
of the owner’s needs. The specification writer is also
usually responsible for continuously reviewing
requests for information concerning technical issues and all specification submittals.
The contractor is responsible for creating a work plan which outlines how the requirements of the
specification will be met at each stage of the installation process. In other words, the techniques, equipment,
materials, and safety measures that will be used to fulfill each of the specification’s requirements. The
inspector, or another authorized team member, is responsible for developing the inspection test plan (ITP).
The ITP outlines all the tasks the coating inspector must perform to verify if the work performed by the
contractor is in conformance with the specification and that all specified procedures have been followed.
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Chapter 16: Inspection Test Plans
Inspection Test Plans
Professional, quality inspection doesn’t just happen;
it requires planning. Showing up on a jobsite without
a well-defined inspection plan and expecting the
project to go well is unrealistic. An Inspection Test
Plan (ITP) is a written document that details the
inspection and testing requirements for a specific
process. ITPs are a quality tool that acts as a “to-do”
list while in the field so that each checkpoint is
properly inspected and documented using the
techniques, instruments, standards, guides, and test methods established by the project specification.
A quality ITP will list all the inspection tasks in chronological order that the inspector must complete in order
to verify if the work performed by the contractor meets the requirements of the specification. This ensures
that all specified procedures have been followed.
The Value of Inspection Test Plans
ITPs are vital tools that provide a range of benefits to
the inspector and also the other key stakeholders on
a project. ITPs enable the inspector to adequately
prepare for their role, provide a means to
communicate the coating project’s progress, and
help ensure that the coating system is installed as
specified.
ITPs as a Planning Tool
Project specifications can be lengthy, complex technical, and legal documents that contain many parts and
sections. The quality requirements for a coating project are oftentimes scattered through the specification. A
thorough, well-organized inspection plan or ITP provides an inspector with a systematic tool that converts the
quality requirements in the project specification into a practical document for use in the field.
By reviewing the ITP prior to each work shift, the inspector can check that they know how to perform the
required inspection tasks, that they have access to the required materials/equipment/test area, and that they
know how to document their inspections.
ITPs as a Communication Tool
ITPs can also serve as a communication tool between the various stakeholders on a project. ITPs help to
ensure that the inspector, contractor, and asset owner have the same information in terms of what work will
be inspected, when the inspections will take place and, the quality requirements that must be met, per the
specification. ITPs, also act as a key communication tool between QA and QC personnel. ITPs also enable the
progress of the project to be tracked and provide evidence that the quality of the job is being monitored,
providing the QA inspector and asset owner confidence in the completed work. To simplify, ITPs enable the
inspector to provide transparency around their responsibilities at each stage of the project and their
inspection results.
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Chapter 16: Inspection Test Plans
ITPs as Quality Control Tools
ITPs help to control the quality of work performed during a coating project and are a central part of both the
asset owner’s QA Plan and the contractor’s QC plan. The use of ITPs to control the quality of work on a coating
project became commonplace in response to ISO 9001. ISO 9001 highlights that to consistently provide
services that meet the client’s requirements, an organization must systematically monitor and measure the
characteristics of the product to verify that the requirements have been met. An ITP is a tangible document
that outlines this process. Without an ITP, an inspector may accidentally miss an inspection task, use the
wrong conformance criteria or the wrong test method. This could result in a deviation being overlooked or a
poor-quality job being performed.
Standards
ƒ
ISO 9001: Quality management systems — Requirements
–
Specifies requirements for a quality management system when an organization needs to
demonstrate its ability to consistently provide products or services that meet the client’s
requirements, in addition to any applicable statutory/regulatory requirements.
Important
It is important to highlight that ITPs are living documents. Living documents, otherwise known as
dynamic documents, are ones that are continuously updated to provide information that is
current and accurate. ITPs are continuously updated during a project to reflect the work
performed and to also show the latest approved and verified procedures. For example, when a
non-conformity is identified or unexpected conditions are found during the project, the
contractor and owner review the issue and authorize necessary changes to the ITP.
CIP Level 1 Inspectors and ITPs
The individual who is responsible for developing a
coating project’s ITP will depend on the project’s bid
process and contractual documents. Some of the
parties who may develop the ITP include the
project’s engineer, specifier, contractor, third-party
inspection firms, or a Level 2 or 3 coating inspector.
If the contractor holds SSPC-QP 1 accreditation, then
they will also have a Quality Control Supervisor on
their team who may be responsible for the
development and distribution of the ITP.
While Level 1 inspectors are typically not responsible for the creation of ITPs, they will be responsible for
implementing them in the field. Level 1 inspectors require the skills to both accurately interpret ITPs and to
recognize when the plan contains missing, ambiguous, or conflicting information that will prevent the
inspector from performing their role. By identifying any issues with the ITP prior to the project commencing,
the inspector can obtain clarification and help prevent issues arising in the field.
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Chapter 16: Inspection Test Plans
SSPC-QP 1 Standard Procedure for Evaluating the Qualifications of Industrial/Marine Painting
Contractors
4.3.1.1 The Contractor shall designate a qualified employee to perform the duties of a Quality Control
Supervisor to manage the Contractor’s quality monitoring processes.
ƒ
Developing, distributing, and collecting completed ITPs is a critical part of this quality monitoring
process.
4.3.2 (f) The Contractor shall demonstrate that project-specific inspection plans ensuring that each major
operation is properly performed and documented on a daily basis during coating projects, are available to
on-site personnel, and are used to perform in-process inspections of work at key hold points.
Inspection Test Plan: Format
There is no industry standard governing the format
of ITPs, but they are typically presented as a
sequential chart or table. ITPs may be simple or very
complex depending on the project for which the plan
is written, and this complexity is commonly reflected
by the number of columns within the chart or table.
The exact format of an ITP often depends on the
specification and other contractual document’s
requirements or inspector and company preference.
Regardless of the format, the primary purpose of the ITP remains the same, to ensure that there is sufficient
information for the inspector to correctly perform each of the required inspection tasks.
ITP Format: Coating Project Stages
To make ITPs easier to navigate, the ITP should
contain separate sections for each stage of the
coating installation process. Within each stage, the
inspection tasks are then listed sequentially. The
hold points listed here should be considered as basic
for most work; however, additional inspection
checkpoints/activities may be added depending on
the project.
Pre-Surface Preparation
The pre-surface preparation inspection hold point occurs after the substrate is pre-cleaned but prior to hand/
power tool cleaning and abrasive blasting. It indicates whether the substrate has been fully prepared for
surface preparation.
Common items inspected during the pre-surface preparation hold point include:
ƒ
Check that the correct abrasive media and coating materials are on-site, damage-free, within shelf life,
properly stored (temperature/humidity of storage areas, FIFO rotation), and batch numbers recorded
ƒ
Measure ambient conditions such as surface and air temperature, dew point, and relative humidity to
ensure moisture will not condense on prepared surfaces
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Chapter 16: Inspection Test Plans
ƒ
Verify the removal of visible grease, oil, etc.
ƒ
Conduct soluble salt contamination or pH testing to identify non-visible contaminants
ƒ
Pre-inspection check to determine the initial condition of steel or rusting/coating condition
ƒ
Assess the condition of steel for inaccessible and other problem areas such as fabrication and surface
defects (welds, bolts, edges, delaminations, dissimilar metals) which could affect coating integrity
Surface Preparation
This inspection hold point takes place after blasting. The purpose is to verify the degree of cleanliness and that
the surface profile yielded from the blasting meets the requirements of the specification.
Common items inspected during the surface preparation hold point may include:
ƒ
Monitor compressed air cleanliness, pressure, and volume
ƒ
Inspect abrasive cleanliness
ƒ
Measure ambient conditions such as surface and air temperature, dew point, and relative humidity
throughout the blasting process
ƒ
Identify surface imperfections that become visible after blast cleaning, such as hackles and slivers that
require scraping or grinding with re-blast cleaning
ƒ
Measure surface profile
ƒ
Inspect surface cleanliness, and other contamination (mill scale, rust, paint) per the level specified
ƒ
Test for presence and inspect removal of soluble salts
ƒ
Verify adequate dust removal
ƒ
Verify surface preparation-to-primer time is not exceeded
Pre-Coatings Application
This inspection hold point occurs immediately prior to the coating or lining application. Common items
inspected during this hold point include:
ƒ
Inspect surface cleanliness to establish whether previously approved surfaces have become recontaminated with abrasive, dust, dirt, oil, or flash rusting that can inhibit adhesion of the coating
ƒ
Verify ambient conditions are acceptable before the coating is mixed and are likely to remain acceptable
during application
ƒ
Verify the correct coating components are being mixed/strained according to the PDS
ƒ
Verify proper type and amount of thinner, if used
ƒ
Verify induction time per PDS
ƒ
Measure coating material temperature
ƒ
Verify mix is applied prior to pot life expiration
Coating Application
Items inspected during the coating application hold point are inspected before each coating layer is applied.
These can include:
ƒ
Measure ambient conditions prior to each coat applied and throughout application
ƒ
Ensure coating application equipment and methods meets the manufacturer’s requirements in the PDS
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CIP Level 1
Chapter 16: Inspection Test Plans
ƒ
Verify stripe coating
ƒ
Measure wet film thickness when dry film thickness measurements are not possible
ƒ
Observe minimum/maximum recoat window for each coat applied
ƒ
Inspect for visible defects that occurred during application that may cause premature failure if left
undetected, so they can be repaired prior to application of the next coat
ƒ
Verify inter-coat cleanliness to avoid contamination
ƒ
Verify acceptable degree of cure on each coat before subsequent coats are applied
Post-Coating Application
Items inspected during the post-coating application hold point are inspected after each coating layer is
applied. These often include:
ƒ
Measure film thickness of each individual coat
ƒ
Verify that the final dry film thickness requirement of the entire coating system has been met
ƒ
Perform pinhole/holiday testing
ƒ
Measure ambient conditions to ensure proper curing
ƒ
Identify any visual defects such as overspray, pinholes, lack of adhesion, etc. that require repair
ƒ
Perform curing tests
Final Inspection
A final inspection will verify that all touch-ups or other corrective actions meet project specification
requirements satisfactorily. Common items inspected during this hold point include:
ƒ
Inspect all touch-ups or other corrective actions to ensure defective, damaged, and deficient areas are
repaired to meet specification requirements
ƒ
Confirm project completion per specification requirements
ƒ
Prepare final inspection report/documentation
ƒ
Ensure removal of waste and that the jobsite is restored to its original condition
Important
On some projects, work on the project may also be halted or stopped at certain steps in the
installation process and cannot resume until the inspector has verified conformance; this is
known as a hold point inspection.
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Chapter 16: Inspection Test Plans
ITP Format: Basic
The process of developing an ITP begins with the
inspector carefully navigating through the
specification to extract the inspection elements and
quality requirements and then transferring them to
a separate chart. Keep in mind that the inspection
requirements may not be written in the specification
in the order in which they will occur during the
project. As such, while reading, the inspector may
want to highlight the important items and inspection
criteria for easy reference in the future.
In addition to the specification, other guidance documents may be required in order to properly fill out the
ITP, including product data sheets for each material used on the project and any industry standards
referenced within the specification.
A basic ITP, at a minimum, should include:
1. The portion of work (or specific hold point) that must be inspected as required by the specification.
2. How the work will be inspected (i.e., test method or procedure to be followed).
3. The minimum standard (conformance or acceptance criteria) the work must meet.
In most ITPs, these categories of information will be arranged in a table as column headings. A simple table
containing these three categories is usually adequate for most projects. Whereas other projects will require a
more complex ITP.
ITP Format: Complex
In this second example, three additional categories
of information (shown in blue) have been added to
the ITP. These categories outline the referenced
industry standard, the frequency with which the
inspection task must take place, and the section of
the specification that the inspection task was
sourced. Other ITPs may outline where the results of
the task are to be recorded, safety guidelines,
required equipment, general notes, or the
signatures of the inspector performing the inspection and the supervising parties. The more complex ITP
format is typically preferred as the additional detail provides the inspector with a more complete inspection
support tool.
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CIP Level 1
Item
Chapter 16: Inspection Test Plans
Activity
Inspection
Method
Acceptance
Criteria
Standard /
Test
Reference
Frequency
Spec
Ref.
4.2
Visual
No visible oil or
grease
contamination
SSPC-SP 1
100% of
surfaces prior to
blasting
Verify compressed
air cleanliness
Blotter Test
No visible oil or
water on collector
ASTM D4285
Once per shift
4.3.4
Verify surface
chloride removal
Latex patch/
sleeve
< 7 µg/cm2
SSPC Guide
15
3 tests per
9m2/100 sq. ft.
4.3.4.1
4
Abrasive type &
cleanliness
Vial/Jar Test
(oil);
Conductivity
Meter
Expendable;
angular; no oil;
<1000 µS/cm
SSPC AB 1
ASTM D7237
ASTM D4940
Each lot
4.7
5
Post blast
cleanliness
Visual
SSPC-VIS 1
Near White Metal
blast
NACE No 2/
SSPC-SP 10
100% of
surfaces prior to
coating
3.2
6
Removal of dust
and blast cleaning
products
Dust tape test Level 2
ISO 8502-3
Post blast
3.7
7
Surface profile
Replica Tape
ASTM D4417
Method C
Post blast
2.8.1
1
Verify pre-blast
cleanliness
2
3
2.0-3.5 mils/
51-89 μm
The above ITP contains the following categories of information:
ƒ
Item Number/Task Sequence
ƒ
Inspection Activity/Hold Points
–
ƒ
Inspection Method
–
ƒ
How often each task or inspection test is performed
Specification Reference
–
8
Indicates the industry standard or test method to be referenced when carrying out the inspection task
Frequency
–
ƒ
Project specification requirements (conformance criteria) that must be met
Standard/Test Method Reference
–
ƒ
Instrumentation and/or specific test methods or procedures required by the specification
Acceptance Criteria
–
ƒ
Identification of the inspection activities for each phase of work as outlined in the specification
Location in the specification where the quality requirement is listed
© NACE International
Chapter 16: Inspection Test Plans
Practical Lab/Self-Study
Note this lab may be conducted as a classroom activity, time permitting, or as a self-study homework
assignment. This exercise is designed to provide students with the opportunity to review excerpts from
real-world ITPs and other guidance documents. Students will then determine if the provided ITPs provide
clear and sufficient information to perform the listed inspection tasks. This practical lab involves two
activities.
Once you have completed the two activities, please refer to the answer key in the Reference tab to
check your answers.
Activity 1
Scenario:
Next week you will be joining a pipeline project as a CIP Level 1 inspector. Due to the large scale of the
project, your role will focus on just the coating application stage. Your supervisor has just emailed you the
ITP as well as the relevant excerpts from the specification and PDS.
1. Read the specification and PDS.
2. Identify any inconsistencies, ambiguities, or omissions within the ITP.
ƒ
Inconsistencies: Refers to information that differs between the ITP and other guidance documents.
ƒ
Ambiguities: Refers to a lack of information, which could prevent the inspector from implementing
the ITP to a high standard.
ƒ
Omissions: Refers to information that is missing from the ITP.
Activity 2
Scenario:
The company you work for has been hired on Thursday at 4pm for a project that begins on Monday. Your
team will be fulfilling the QC Inspection role. Due to the short notice your team leader has asked you to
identify any missing information from the ITP.
1. Read the specification and standards.
2. Identify the information missing from the ITP.
3. Using the excerpts from the specification and standards, fill in the blank portions of the ITP template.
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CIP Level 1
Chapter 16: Inspection Test Plans
Activity 1
1. Read the excerpts below.
7. Coating Application (Specification Excerpt)
1. Surfaces to be coated shall be free of moisture, oil, grease, dust, and any other visible contaminants prior
to the application of the coating.
2. Stripe coating by brush is required for welds, nuts, bolts, edges, and corners.
3. The relative humidity, air, and steel surface temperature shall be monitored, and the values recorded at
least once every three hours. The measured conditions shall adhere to the manufacturer’s requirements,
including measuring the dew point. Steel temperature must be at least 5 degrees (°F) above the dew
point at the time of any surface preparation or coating application activities.
4. Spray application is preferred method; however, application by brush or roller may be used selectively if a
high-quality finish can be achieved.
5. The Contractor shall regularly monitor wet film thickness for conformance with the manufacturer’s
requirements.
6. Dry film thickness of each layer shall be measured in accordance with SSPC-PA 2, using an electronic
gauge. The measured thickness must conform to the manufacturer’s requirements.
7. Each coat shall be free from runs, sags, dry spray, drips, pinholes missed or skipped areas, embedded
debris, and other visible defects detrimental to coating performance.
8. Each coating layer shall adhere to the manufacturer’s stated recoat window.
9. After the system has cured, wet sponge holiday testing shall be performed in accordance with NACE
SP0188. Any holidays identified shall be marked with chalk as a defect
ABC Epoxy (PDS Excerpt)
Application Conditions
Drying Schedule
Air & Surface
Temperature
Minimum of 1.7°C (35°F)
Maximum 49°C (120°F)
Dew Point
Surface Temp. > 2.8°C
(5°F) above dew point
Relative Humidity
85% maximum
Recommended Film Thickness
25°C (77°F)
1.7°C (35°F)
To Touch
2 hours
1.5 hours
To Recoat
4.5 hours
8 hours
To Cure
7 days
4 days
4 hours
2 hours
30 minutes
15 minutes
Minimum
Maximum
Pot Life
Wet Film
7.0 mils
175 µm
13.5 mils
338 µm
Sweat-in-Time
Dry Film
5.0 mils
125 µm
10.0 mils
250 µm
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© NACE International
Chapter 16: Inspection Test Plans
2. Circle any inconsistencies, omissions, and ambiguities in the ITP based on the
information from the specification and PDS excerpts.
Inspection Test Plan (Coating Application)
No.
Activity
Inspection
Equipment
Controlling
Documents
Acceptance Criteria
Frequency
7.1
Inspect the precleaned surface
Visual inspection
Specification
Free of visible
contaminants
All areas
7.2
Observe the stripe
coating by roller
Visual inspection
Specification
All welds, nuts, bolts,
edges, and corners
stripe coated
All areas
7.3
Monitor the
environmental
conditions
Digital all-in-one
device or a
thermometer &
hygrometer
Surface Temp: 35°F 49°C
PDS
Surface Temp at least
5°F above dew point
At the beginning of
each shift
Humidity < 85%
7.4
Inspect roller and
brush application
(if applicable)
Visual inspection
7.5
Measure the wet
film thickness
Comb Gauge
7.6
Inspect the coating
Visual inspection
film
7.7
Monitor the recoat
window
7.8
Perform holiday
testing
—
Low-voltage wet
sponge Chalk
Specification
PDS
Specification
PDS
NACE SP0188
High-quality finish
achieved
Areas coated by
brush or roller
(excluding
stripping)
175 μm - 338 μm
One per section or
as needed
Coating film is free
from visible defects
and debris
All areas
8 hours minimum
Each layer, all
areas
No holidays. Identified
holidays to be marked All areas
and reported
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Chapter 16: Inspection Test Plans
Activity 2
1. Read the excerpts below.
5. Surface Preparation (Specification Excerpt)
Pre-Treatment
a. Any sharp edges and weld defects such as spatter, undercut, etc. shall be repaired. Any defects which
show up after blast cleaning shall be repaired and re-blasted. All edges shall be radiused to at least a
45-degree angle unless otherwise specified.
b. Any oil, grease, or other contamination shall be removed by a method designated in SSPC-SP 1.
Dry Abrasive Blasting
a. Blast cleaning shall not be carried out adjacent to coating operations or wet (coated) surfaces.
b. All abrasives shall be clean, dry, and free from foreign matter as verified with a vial test.
c. The compressed air supply shall be free from oil and moisture. The presence of oil and water shall be
determined in accordance with ASTM D4285 following every compressor start-up.
d. Spent abrasive and dust shall be removed from the surface by blowing with clean, dry air and/or vacuum
cleaning.
e. The surface shall be blast cleaned with steel grit or garnet to NACE No.2/SSPC-SP 10 and SSPC-VIS 1.
f. The surface will possess an angular profile and measure between 75 microns and 100 microns, as per
ASTM D4417, Method C.
g. If the freshly blasted surface shows patches of black or brown discoloration within an hour of blasting,
the surface shall be tested for chloride contamination per ISO 8502, Part 6 and Part 9. Residual chloride
contamination shall be less than 50 milligrams per square meter (5 μg/cm2).
NACE No.2 / SSPC-SP 10 (Excerpt)
Definition: When viewed without magnification, the surface shall be free of all visible oil, grease, dust, dirt,
mill scale, rust, coating, oxides, corrosion products, and other foreign matter. Random staining shall be
limited to no more than 5 percent of each unit area.
ASTM D4417 Method C (Excerpt)
Test Method Summary: A composite plastic tape (replica tape) is impressed into the blast cleaned surface,
forming a reverse image of the profile. The average maximum peak-to-valley distance can be measured
using a suitable thickness gauge (micrometer).
ASTM D4285 (Excerpt)
Use: This test method is a visual examination technique for determining oil and water in compressed air.
Apparatus: An absorbent collector such as absorbent paper or cloth. Non-absorbent collector such as rigid
transparent plastic.
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Chapter 16: Inspection Test Plans
2. Identify the missing information in the ITP below and then fill in the gaps using the
information from the excerpts.
5. Pre-treatment
No.
Activity
Inspection
Equipment
Controlling
Documents
5.1
Inspect the precleaned surface
Visual inspection
Specification
5.2
Inspect the precleaning
Visual inspection
SSPC-SP 1
Visual inspection
Specification
Visual inspection
Vial Test
Specification
Visual inspection
Specification
Acceptance Criteria
Sharp edges rounded and weld defects
ground smooth & edges radius to 45°
6. Surface Preparation
6.1
Verify conditions are
suitable for blasting
6.3
Verify abrasive type
6.4
Test the cleanliness
of compressed air
6.5
Inspect the postblast clean-up
6.6
Assess surface
cleanliness
NACE No.2 /
SSPC-SP 10
6.7
Measure the surface
profile
ASTM D4417
Method C
6.8
Media is clean, dry, and free from foreign
matter
No indication of water or oil discoloration
present
Visual inspection
Specification
Visual inspection
Specification
6.9
Inspect the surface
for deterioration
Visual inspection
Specification
6.10
Measure chloride
contamination (if
required by 6.9)
Bresle Patch Kit
Conductivity Meter
ISO 8502
Part 6 & 9
No spent abrasive or dust on the surface
Surface profile:
– 75 - 100 μm
The surface has no patches of black or
brown discoloration within an hour of
blasting
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Chapter 17: Math
Chapter 17:
Practical Math
17.1 Introduction
Learning Objectives
By the end of Chapter 17, students should be able to:
1. Recall the common mathematical formulas used in the coatings industry.
2. Solve common calculations relating to everyday coating inspection activities.
Coating inspectors frequently have to perform
mathematical calculations during everyday
inspection tasks. If unprepared, these calculations
can be one of the more challenging aspects of a
coating inspector’s role. As a result, it is essential that
inspectors are familiar with commonly performed
mathematical calculations, including:
ƒ
Averaging when taking dry film thickness
measurements
ƒ
Converting dry film thickness to wet film
thickness
ƒ
Calculating spread rates/coverage (including losses) for various coatings
ƒ
Determining material consumption
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CIP Level 1
Chapter 17: Math
17.2 Calculations
Calculating Averages
Inspector Role
Inspectors oftentimes need to evaluate multiple
surface profile for film thickness readings through
averaging in order to determine if the specification is
met. An average is simply a number that represents
the different values in a group of numbers.
Performing the Calculation
To obtain the average of a set of values, simply add
all the values together to generate a total (a “sum”), then divide the sum by the number of values in the set. In
other words, it is the sum divided by the count.
Example
What is the average of the three individual gauge readings measured in Area A?
Imperial
Metric
Step 1: Calculate the Sum
15 + 16 + 17 = 48
Step 1: Calculate the Sum
381 + 406 + 431 = 1,218
Step 2: Divide the Sum by the number of values in
the set
48 ÷ 3 = 16 mils
Step 2: Divide the Sum by the number of values in
the set
1,218 ÷ 3 = 406 µm
Calculating Acceptable DFT Ranges
Inspector Role
As mentioned, averages are used when taking multiple dry film thickness (DFT) readings. Typically, a coating
specification will list the required DFT as a range (e.g., 4-6 mils/coat) that must be achieved rather than a single
value (e.g., 5 mils/coat). Even with this range, it is difficult for an applicator to consistently achieve the required
film thickness, especially on more complex portions of a structure. As a result, specifications will allow a
degree of tolerance for individual gauge readings. The amount of tolerance allowed varies between
specifications and standards. For example, SSPC-PA 2, Restriction Level 3 allows spot measurements to be
between 80% of the minimum specified thickness and 120% of the maximum specified thickness to be in
conformance. SSPC-PA defines a spot measurement as the average of three, or at least three gauge readings
made within a 4-cm (approximately [~]1.5 in) diameter circle. Spot measurements are usually taken within
close proximity of each other and then averaged).
Performing the Calculation
To calculate this range, simply convert the percentages into decimals and multiply them by their respective
DFT requirements.
2
© NACE International
Chapter 17: Math
Example
If we have a required DFT range of 4-6 mils (101.6 – 152.4 µm) and we are using SSPC-PA 2, Restriction Level 3
(80% of minimum/120% of maximum), the calculation would be as follows:
Minimum
Maximum
= 4 mils (101.6 µm) x .80
= 3.2 mils (81.28 µm)
= 6 mils (152.4 µm) x 1.20
= 7.2 mils (182.88 µm)
Therefore, the averaged spot checks can have an acceptable range of 3.2 mils (81.28 µm) – 7.2 mils (182.88
µm).
Understanding Volume Solids
Volume solids is the measure of volume of a coating
that is left after the coating has dried or cured. All
coatings have solids, which include pigments and
resins/binders that form the paint coating after the
solvent evaporates. Volume solids of a coating are
listed on the manufacturer’s Product Data Sheet as a
percentage of the total volume of paint. This
percentage can be expressed as VS% (Solids Volume
Percentage) or SBV% (Solids by Volume). The volume
solids percentage is very important when calculating film thickness and coverage. Keep in mind that adding
thinner will reduce the volume solids.
Calculating Wet Film Thickness
Wet film thickness is the thickness of the coating
immediately after application, prior to any curing or
solvent evaporation. As the paint dries or cures, the
solvent evaporates, leaving only the solids on the
surface, which we measure as dry film thickness.
Inspector Role
Understanding the relationship between a coating’s
wet and dry film thickness allows you to measure the
coating when wet and accurately predict the final dry outcome. Although, in most cases, the inspector is
concerned with the dry film thickness and not the wet film thickness, it is important for every inspector to be
cognizant of this relationship. The Contractor must ensure that the proper wet film thickness is applied in
order to comply with the dry film thickness requirements of the specification. If the coating is applied too thin
or too thick, then rework is often required.
Unfortunately, coating manufacturers do not always publish a wet film thickness value on their application
instructions because it can vary depending on how much thinner is added to the coating and the actual dry
film thickness that is specified. Therefore, it is important to know how to calculate a target wet film thickness
for both un-thinned and thinned coatings.
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CIP Level 1
Chapter 17: Math
Performing the Calculation
If we had a coating that was 100% solids or 100% SBV (solids by volume), then all of the solids would stay on
the surface when they dried or cured. In that situation, the WFT and DFT would be exactly the same. Since
coatings need solvent in order to be applied, most of the time, the volume by solids is less than 100%. As
mentioned earlier, this is known as the Solids by Volume (SBV), and it is the percentage of the coating that will
remain on the surface after the solvent has evaporated. When applying an un-thinned coating, to calculate the
target WFT that needs to be applied in order to achieve the specified DFT, we will need the following formula:
Example
Wet Film Thickness = Dry Film Thickness ÷ Solids by Volume, (WFT = DFT ÷ SBV)
Imperial
Metric
If we have a coating that is 30% solids by volume
and we need to apply the correct wet film
thickness to get a dry film thickness of 6 mils (152
If we have a coating that is 35% SBV and we need a
DFT of 125 µm we would plug the data into the
formula as follows:
µm), we simply convert the percentage into a
decimal by moving the decimal two places to the
left. For example, 75% is 0.75. Next, we plug the
data into the formula:
WFT = DFT ÷ SBV
WFT = DFT ÷ SBV
WFT = 6 ÷ .30
WFT = 125 ÷ .35
WFT = 20 mils (508 µm)
WFT = 357 µm
Mentor Tip
An easy saying to remember the dry film thickness formula is “dry to wet you divide”.
Important
When the solids by volume content is indicated on the coating manufacturer’s product data sheet, it is
typically expressed as a percent (%). Often there is a solids by weight value on the product data sheet as
well. Do not use this value.
Adjusting for Thinner
Industrial coatings are sometimes thinned to allow them to be applied more easily. If the project specification
and the coating manufacturer permit thinner to be added to the coating, the amount of thinner that will be
added must be taken into consideration when calculating the target wet film thickness. This is because the
thinner becomes part of the wet film that is applied to the surface but is not part of the dry film that remains
on the surface (the thinner will evaporate into the air). In other words, thinner increases the total volume
without increasing the amount of solids. When adding thinner to a coating, the Contractor is effectively adding
more solvent.
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© NACE International
Chapter 17: Math
Inspector Role
By understanding and calculating the percentage of thinner that has been added, we can also determine what
the WFT should be so that the specified DFT will be achieved. Coating manufacturers typically communicate
the amount of thinner to add based on a percentage of the total volume of coating mixed for application (e.g.,
15%). As long as we know the volume solids of a product, the dry film thickness required, and the precise
amount of thinner that has been added, we can calculate the wet film thickness.
Performing the Calculation
Calculating the target wet film thickness when thinner is added requires one additional step.
We first must determine the Adjusted SBV by adding the thinner percentage to 100%, then dividing by the
SBV. Then find the target Wet film thickness by dividing the Dry Film Thickness by the SBV. Below is the
formula:
Adjusted SBV = SBV ÷ 100% + Thinner %
Note: 100% + Thinner % is derived by adding the thinner to the total amount of liquid coating to find the
total volume, including thinner.
Example
If a coating that is 85% SBV, is thinned 25% and must be applied at a DFT of 7 mils (177.8 µm), we would plug in
the numbers as follows to determine the WFT:
Step 1: Calculate the Adjusted SBV
Adjusted SBV = SBV ÷ 100% + Thinner %
Adjusted SBV = 85% ÷ 100% + 25%
Adjusted SBV = .85 ÷ 1.25
Adjusted SBV = .68
Now we can calculate the target WFT based on the Adjusted SBV with the same formula we have already used:
Step 2: Calculate the WFT
WFT = DFT ÷ Adjusted SBV
WFT = 7 (177.8 µm) ÷ 0.68
WFT = 10.29 mils (261.47 µm)
5
CIP Level 1
Chapter 17: Math
Calculating Dry Film Thickness
Inspector Role
Inspectors use the DFT formula to determine
whether or not the wet paint film is the right
thickness to achieve the specified dry film thickness.
Performing the Calculation
To calculate the Dry Film Thickness, multiply the
measured Wet Film Thickness by the Solids by
Volume. The formula is written as:
Dry Film Thickness = Wet Film Thickness x Solids by Volume, (DFT = WFT x SBV)
Example
If you have a coating with a WFT of 9.2 mils (233.6 µm) and SBV of 65%, what is the DFT?
Imperial
Metric
DFT = WFT x SBV
DFT = WFT x SBV
DFT = 9.2 x .65
DFT = 233.6 µm x .65
DFT = 5.98 mils
DFT = 151.8 µm
Mentor Tip
An easy saying to remember the dry film thickness formula is “wet to dry you multiply”.
Theoretical Coverage: Spread Rate
Inspector Role
Inspectors may be required to calculate the
spreading rate of a material based on the DFT
required and the percent of volume solids of the
coating.
Understanding Theoretical Coverage (Spreading
Rate)
Coating manufacturers frequently provide a rate of
coverage (square meters per liter or square feet per gallon) on their product data sheets. However, this rate is
theoretical. Theoretical coverage or spread rate, as it is sometimes called, is based on applying a coating to a
smooth, flat surface under perfect conditions, where there is no loss or waste during mixing and application.
It is determined by using the square footage or meters covered by one gallon of paint spread at a thickness of
1 mil (1 µm) DFT with a 100% solids coating.
6
© NACE International
Chapter 17: Math
For example, if a gallon of paint contained 100% solids and if it could be applied without losses, it would cover
1,604 ft2 at a thickness of 1 mil. In metric units, one liter of paint with 100% solids will cover 1,000 m2 at a
thickness of 1 µm with no loss. This figure (1,604 ft2 per gal or 1,000 m2 per liter) is used as the starting point
when calculating the spread rate or coverage of a coating.
However, most coatings are not 100% solids. In fact, the actual coverage obtained from any gallon or liter of
paint is dependent on its nonvolatile or solids content. We also know that many job specifications require a
DFT greater than 1 mil or 1 µm.
As such, the spread rate of a coating is calculated based on the theoretical coverage per gallon/liter using the
actual volume solids (from the coating manufacturer’s PDS) and the target coating thickness (from the project
specification) with the following formula:
Imperial:
Metric
1,604 sq. ft x SBV ÷ DFT (in mils)
1,000 m2 x SBV ÷ DFT (in microns)
Calculating Theoretical Coverage or Spread Rate
The spread rate of a coating is determined by using the theoretical coverage of 1,604 sq ft per gal or 1,000 m2
per liter. That number is then multiplied by a decimal equivalent of volume solids content (e.g., 0.95 for a 95%
solids coating). After which, the number is divided by the target dry film thickness of the applied coating.
Example
Imperial
Metric
If a coating has 60% SBV and needs to be applied
at a DFT of 6 mils, the calculation will be as follows:
If a coating has 60% SBV and needs to be applied
at a DFT of 150 microns, the calculation will be:
1604 sq. ft x SBV ÷ DFT (mils)
1000 m2 x SBV ÷ DFT (microns)
1604 x 0.60 ÷ 6
1000 x 0.60 ÷ 150
160 sq. ft/gal
4 m2/L
Note: This calculation is still considered theoretical because we have not accounted for material loss due
to mixing and application.
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CIP Level 1
Chapter 17: Math
Practical Coverage: Transfer Efficiency (TE)
Inspector Role
The practical coverage of a coating can be used to
verify that there is an adequate amount of each
coating material on-site in order to prevent project
delays associated with material shortages.
Understanding Practical Coverage and Transfer
Efficiency
We have learned that theoretical coverage assumes
that every drop of paint that is sprayed will be transferred to the surface. In practice, we know this is not
possible due to application losses, which are dependent on many factors, including wind, application
technique, application equipment, and type/profile of the substrate to be coated. Since loss factors vary
depending on the situation, the Contractor typically generates a transfer efficiency rating based on the
specifics of the project when determining how much material to order.
Transfer efficiency or TE refers to the amount of material that adheres to the substrate compared to the
amount sprayed. It is derived from how much material is lost during the application process. TE is expressed
as the percentage of the weight of solids sprayed versus the weight of solids gained by the target. As an
example, 60 percent transfer efficiency means that 60 percent of the weight of the solids in the material that
was sprayed actually reaches the target. The balance of 40 percent was lost during the application process.
Given the theoretical coverage rate (1,604 sq. ft. at a 1 mil DFT or 1,000 m2 at 1µm DFT) and by estimating the
transfer efficiency or loss factor, the practical coverage of a coating can be determined. Practical coverage
makes allowances for application losses and is a more reliable indicator of the actual amount of coating that
will be needed to obtain the specified dry film thickness. Once the practical coverage is determined, you can
calculate how many gallons or liters of paint are needed for the job based on the size of the area to be
painted. Practical coverage can be determined using the following formula:
Practical Coverage (Imperial) = 1,604 x SBV x TE ÷ DFT (mils)
Practical Coverage (Metric) = 1,000 x SBV x TE ÷ DFT (microns)
Calculating Practical Coverage
Calculating Transfer Efficiency
Transfer Efficiency (TE) is typically expressed as a
percentage, such as 25%. It represents the amount
of coating that adheres to the surface when
compared to the amount of material that was
originally sprayed. To calculate the transfer
efficiency, simply subtract the loss percentage from
100. For example, if the loss was 25% the equation
would be 100% - 25% = 75% transfer efficiency. Next,
you convert the percentage to a decimal by moving the decimal two places to the left. For example, 75% is
0.75.
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Chapter 17: Math
Another way to determine the transfer efficiency is to convert the loss percentage to a decimal and subtract it
from 1. The formula is as follows:
TE = 100% - loss % (expressed in decimal)
For example, if the loss is 25% you would plug it into the formula as shown:
TE = 100% - 25 % = 75%
TE = 1.0 - 0.25 = 0.75 (move the decimal two places to the left)
TE = 0.75
Calculating Practical Coverage
After the transfer efficiency has been determined, next we calculate the practical coverage using the formula:
Practical Coverage = 1,604 x SBV x TE ÷ DFT
Example
If a coating has 68% SBV, it needs to be applied at 5 mils (127 µm) DFT, and a loss of 12% is calculated; the
steps are as follows:
Step 1: Calculate TE
TE = 100 % - loss %
TE = 1.0 - 0.12
TE = 0.88
Step 2: Calculate Practical Coverage
Imperial
Metric
Practical Coverage = 1,604 x SBV x TE ÷ DFT (mils)
Practical Coverage = 1,000 x SBV x TE ÷ DFT
(microns)
Practical Coverage = 1,604 x 0.68 x 0.88 ÷ 5
Practical Coverage = 192 sq. ft
Practical Coverage = 1,000 x 0.68 x 0.88 ÷ 127
Practical Coverage = 4.7 m2
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CIP Level 1
Chapter 17: Math
Calculating Material Consumption
Inspector Role
If an inspector is required to determine if there is
enough coating material on-site to complete a
project, they will need to calculate material
consumption.
Performing the Calculation
Once you know the practical coverage, you can
divide that number into the total square footage to
be coated to determine how many gallons (or liters) of coating will be needed for the job. Here is the formula:
Material Consumption = Area ÷ Practical Coverage
Example
Imperial
Metric
On a project, the Contractor is using paint with
52% SBV and is applying it at 1.5 mils DFT with a
transfer efficiency of 30%. The project will need the
coating to cover 35,000 sq. ft. The calculations
would be as follows:
The Contractor is using paint with 52% SBV and is
applying it at 38 µm DFT with a transfer efficiency
of 30%. The project will need the coating to cover
800 m2. The calculations would be as follows
Step 1: Calculate Practical Coverage
Step 1: Calculate Practical Coverage
Practical Coverage = 1,604 x SBV x TE ÷ DFT
Practical Coverage = 1,000 x SBV x TE ÷ DFT
= 1,604 x 0.52 x 0.30 ÷ 1.5
= 1,000 x 0.52 x 0.30 ÷ 38
= 166.8 sq. ft (rounded to 167 sq. ft)
= 4.10 m2 (rounded to 4 m2)
Step 2: Calculate Material Consumption
Step 2: Calculate Material Consumption
Material Consumption = Area ÷ Practical Coverage
Material Consumption = Area ÷ Practical Coverage
= 35,000 ÷ 167
= 800 ÷ 4
= 209.58 gallons (rounded to 210 gallons)
= 200 liters
10
© NACE International
Chapter 17: Math
17.3 Review
Convert percentages to decimal format
Replace the percentage sign with a decimal point, then move
the decimal point two places to the left or divide the % by
100.
Average numbers
The average of a set of numbers is the sum of the numbers
divided by the total number of values in the set.
Convert units of measurement
Imperial: mils x 25.4 = μm
Imperial: lbs./gal x 119.8 = g/L
Metric: μm ÷ 25.4 = mils
Metric: g/L ÷ 119.8 = lbs./gal
Calculate Wet Film Thickness (WFT)
WFT = DFT ÷ SBV
Adjust for thinner when calculating WFT
Adjusted SBV = SBV ÷ 100% + Thinner %
Calculate Dry Film Thickness (DFT)
DFT = WFT x SBV
Calculate Theoretical Coverage
1,604 x SBV ÷ DFT (mils) OR 1,000 m2 x SBV ÷ DFT (µm)
Calculate Transfer Efficiency (TE)
100% − loss % (expressed as a decimal)
Calculate Practical Coverage
1,604 x SBV x TE ÷ DFT (mils) OR 1,000 m2 x SBV x TE ÷ DFT
(µm)
Material Consumption
Area ÷ Practical Coverage
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CIP Level 1
Chapter 17: Math
Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. Dry film thickness is specified at 12-15 mils at SSPC-PA 2 restriction level 3. (Spot readings
shall be within 80% to 120% of specified values)
Calculate the spot measurements and determine whether the area measured meets the
specification.
Measurement
Total
Area
Reading 1
Reading 2
Reading 3
A
10 mils
12 mils
12 mils
B
12 mils
14 mils
13 mils
C
15 mils
14 mils
14 mils
D
14 mils
13 mils
10 mils
E
12 mils
13 mils
11 mils
(1+2+3)
Average
Complies
(Total ÷ No. of
Measurements)
(Yes/No)
Overall Average
2. The following data is provided for a given coating:
ƒ
DFT = 5 mils = (127 µm)
ƒ
SBV = 45%
ƒ
Loss Calculation = 10%
ƒ
Thinner = 15%
Imperial
12
Metric
© NACE International
Chapter 17: Math
Self-Study Review
Answer the following questions for additional practice. To check your responses, refer to the
Answer Key in the Reference tab.
1. Convert the Solids by Volume (SBV) for each example into decimal format.
Solvent
Solvent by
volume 15%
Solids
Solids by
volume 85%
Solvent
Solvent by
volume 30%
Solids
Solids by
volume 70%
Solvent
Solids
Solvent
Solids
Solvent by
volume 45%
Solids by
volume 55%
Solvent by
volume 65%
Solids by
volume 35%
2. If the PDS states the following, what is the WFT?
DFT: Range of 2-4 mils (51-102 microns)
SBV: 75%
(Answer in either imperial or metric units)
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CIP Level 1
Chapter 17: Math
The project specification requires the DFT of the primer to measure between 150-200 microns
per SSPC-PA 2 Restriction Level 4 which states a tolerance range of 80% of the minimum
specified DFT and 150% of the maximum.
3. Does reading group A fall within the tolerance limits? What about reading group B?
4. If a coating is 70% SBV and is thinned 15%, what WFT do you need to apply to get a DFT of 9
mils (229 µm)?
(Answer in either imperial or metric units)
14
© NACE International
Chapter 17: Math
5. If a coating is 75% SBV and is thinned 12.5%, what WFT do you need to apply to get a DFT
between 2-4 mils (51-102 µm)?
(Answer in either imperial or metric units)
6. The following data is provided for a given coating:
ƒ
DFT = 5 mils (127 µm)
ƒ
SBV = 45%
ƒ
Loss Calculation = 10%
(Answer in either imperial or metric units)
Imperial
The Contractor must apply the coating to
5,000 ft2. How many gallons must the
Contractor buy?
Metric
The Contractor must apply the coating to
500 m2. How many liters must the Contractor
buy?
15
CIP Level 1
Chapter 17: Math
7. Determine the theoretical coverage for the examples shown.
A coating has 65% SBV and will be applied at a
DFT of 1 mil.
A coating has a 75% SBV and will be applied at a
DFT of 220 microns.
A coating has a 35% SBV and will be applied at a A coating has a 40% SBV and will be applied at a
DFT of 80 microns.
DFT of 4 mils.
8. The Contractor must apply the coating to 2,323 m2. How many liters must the Contractor
buy?
The following data is provided for a given coating:
16
ƒ
DFT = 85 µm
ƒ
SBV = 75%
ƒ
Loss Calculation = 20%
© NACE International
Chapter 18: Measuring Environmental Conditions
Chapter 18:
Measuring
Environmental
Conditions
18.1 Introduction
Learning Objectives
By the end of Chapter 18, students should be able to:
1. Accurately measure surface temperature using a surface contact thermometer or a digital infrared
thermometer.
2. Accurately measure the air temperature, humidity, and calculate dew point using a sling psychrometer
(with a psychrometric table/calculator) and a digital dew point meter.
3. Accurately measure wind speed using an anemometer.
1
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Inspection Instrument: Environmental Conditions
There is a wide range of instruments that can be utilized to measure environmental conditions. Some of these
instruments are designed to measure one type of environmental condition, such as magnetic surface contact
thermometers. Other instruments can measure a range of conditions either simultaneously or individually by
attaching separate probes/peripherals to the core instrument. As an example, digital dew point meters can
measure air temperature, measure relative humidity, and calculate the dew point simultaneously. These
multi-purpose instruments are sometimes referred to as ‘digital all-in-one’ devices. Select digital dew point
meters can also measure surface temperature and wind speed but often require separate attachments for
these measurements.
Reading Digital Instruments
The displays of digital instruments have a limited
amount of space to list all the relevant information.
This is particularly relevant when measuring
environmental conditions, as many of the
instruments will measure a range of conditions
simultaneously. To accommodate this limitation,
abbreviations or symbols are used to represent each
of the conditions. For example:
ƒ
Relative Humidity = RH or RH%
ƒ
Dry Bulb Temperature = Tdb
ƒ
Surface Temperature = Ts
ƒ
Dew Point Temperature (calculated) = Td
ƒ
Air Temperature = Ta
ƒ
Delta T = TΔ or Ts-Td
ƒ
Wet Bulb Temperature = Twb or Tw
ƒ
Windspeed = V or the unit of measurement (e.g.,
mph, kph, m/s, knots)
Note that the inspector should always review the manufacturer’s user manual when working with new
instruments, as the symbols can vary.
2
© NACE International
Chapter 18: Measuring Environmental Conditions
18.2 Surface Temperature Instruments
Measuring Surface Temperature
Surface temperature is a measure of the
temperature of the surface being blasted or coated.
Surface temperature above and below the required
range can have an adverse impact on the coating
application process. High temperatures can reduce
pot life, reduce re-coat windows, and cause the
coating film to wrinkle. Low temperatures can
increase the viscosity of coating materials and result
in improper curing. Surface temperatures must also
be measured to assess the risk of moisture formation on a substrate. If the surface temperature is not 3°C
(5°F) above the dew point, then moisture can form and adversely impact the final outcome of the project.
Inspectors commonly measure surface temperature with the use of magnetic surface contact thermometers
or digital infrared thermometers.
Magnetic Surface Contact Thermometer
Overview
The magnetic surface contact thermometer
sometimes referred to as a dial type thermometer, is
one of the most common instruments used to
determine substrate temperature. These
thermometers are specifically designed to be used
on any magnetic or horizontal surface as well as
ferrous non-horizontal surfaces.
The instrument consists of a bimetallic sensing element, which is protected from drafts and is in contact with
the surface to be measured. It also includes two high-temperature magnets on the sensing side, which hold
the instrument to the surface. These thermometers do not require batteries but do require time to adjust to
the temperature. They are also available in various scale ranges.
Standards
The following standard describes the use of a Magnetic Surface Contact Thermometer:
ƒ
ASTM D3276 Standard Guide for Painting Inspectors (Metal Substrates)
Note that additional standards may also be available for your region.
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CIP Level 1
Chapter 18: Measuring Environmental Conditions
Method of Operation
To measure surface temperature with a magnetic
contact thermometer:
1. Ensure the substrate is clean and dry to enable
good magnetic attraction
2. Place the magnetic back of the thermometer on
the surface
3. Allow the instrument to stabilize before taking
measurements
ƒ
Stabilization time varies but is usually 3 to 5 minutes
4. Read the dial straight on and record the temperature
Usage Tips & Common Errors
Usage Tips
To help ensure that accurate measurements are
performed:
ƒ
Perform measurements at the actual work
locations
ƒ
Perform multiple readings across multiple points
in the test area to assess the range of
temperatures
–
Include areas that are likely to be hotter or colder than the normal temperature
ƒ
Avoid areas exposed to direct sunlight, wind, thermal radiation, and heating or ventilation ducts when
taking measurements
ƒ
Make sure the thermometer can measure in the range of temperatures anticipated
Mentor Tip
Before using, blow on the back of the thermometer to ensure there is no stray blast media
lodged between the bimetallic spring, as this will affect your readings. Also, tap lightly on the
front of the glass to make sure the needle is not stuck.
Common Errors
Common errors when using magnetic surface contact thermometers includes:
ƒ
Performing readings in direct sunlight, can make the surface temperature appear higher than it is
ƒ
Leaving the instrument in one place for too long
ƒ
Failure to remove debris from the bimetallic spring or contact strip causing a poor connection and
inaccurate readings
ƒ
Reading the instrument at an angle
ƒ
Removing the instrument before it has stabilized.
4
© NACE International
Chapter 18: Measuring Environmental Conditions
Calibration
The instrument’s low cost indicates that it should be replaced if there is any doubt about its accuracy, rather
than send it to a third-party laboratory or back to the manufacturer for calibration.
Digital Infrared Thermometer
Overview
Digital infrared (IR) thermometers are non-contact
thermometers that are used to measure
temperature from a distance. The temperature
provided will be the average temperature of the
whole area within the spot size. If the amount of
infrared energy emitted by an object and its
emissivity are known, the object’s temperature can
be determined.
The most basic digital infrared thermometer consists
of a lens to focus the infrared energy; a detector that
converts the energy to an electrical signal
proportional to the temperature of the target
surface; and the electrical signal display (in
temperature units after compensating for ambient
temperature variation). IR thermometers make it
easier to measure the surface temperature of an
object from a distance without touching it and
generally have a fast-reading response time of one
second.
The infrared thermometer is useful for measuring temperature when other probe-type sensors cannot be
used or do not produce accurate data for a variety of reasons. It is important to note that the laser spot
indicates the target area. However, the measurement is not confined to this spot. All digital infrared
thermometers have a distance-to-target (D/T) or distance-to-spot (D/S) ratio. This measurement tells you the
diameter of the “circle” or spot size of the surface area an IR thermometer will measure at a given distance and
will be listed on the instrument itself or included in the manufacturer’s instructions. For example, a D/T ratio
of 8 to 1 would measure a 1-inch spot at a distance of 8 inches.
Standards
The following standards describe the selection and/or use of Digital Infrared Thermometers:
ƒ
ASTM D3276 Standard Guide for Painting Inspectors (Metal Substrates)
ƒ
ASTM E2847 Standard Test Method for Calibration and Accuracy Verification of Wideband Infrared
Thermometers
ƒ
ASTM WK21204 Guide for the Selection and Use of Wide Band, Low Temperature Infrared Thermometers
Note that additional standards may also be available for your region.
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CIP Level 1
Chapter 18: Measuring Environmental Conditions
Method of Operation
To measure surface temperature with an IR
thermometer:
1. Turn the thermometer on and check the settings,
including the unit of measurement
ƒ
Some thermometers only take individual
readings, whereas others will continuously
record the temperature as it is moved across
the surface
2. Point the thermometer at the target surface area, using the laser pointed as a guide (if applicable)
3. Pull the trigger or press the measure key/button to take a reading
4. Read the surface temperature from the display located on the back of the thermometer above the handle
Note that if continuous readings are required, on some models of IR thermometers, the trigger or
measure key is held, and on others, it will need to be re-triggered for each measurement.
Mentor Tip
The displayed reading is the average temperature of the whole area within the spot size.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Use the laser sight to help target the exact
location to be measured (when included)
ƒ
Some IR thermometers require time to stabilize
to the ambient temperature before use
ƒ
Know the maximum distance the thermometer
can be held from the surface before errors can
occur
–
Check the manufacturer’s instructions for the maximum distance-to-target/spot ratio
Other factors to be aware of when using IR thermometers include:
ƒ
IR thermometers will factor in the surface temp of whatever surfaces are visible within the “circle”
–
Stand close enough to the target surface to keep unintended background elements safely out of the
“circle”
ƒ
The further away the thermometer is held, the greater the margin of error
ƒ
The infrared laser cannot read through transparent surfaces such as glass
6
© NACE International
Chapter 18: Measuring Environmental Conditions
ƒ
They do not measure reflective surfaces accurately, such as stainless steel, some blasted surfaces or
aluminum
–
Shiny or reflective surfaces can be difficult to measure with an infrared thermometer, as they tend to
reflect ambient infrared energy instead of their own.
–
A piece of electrical tape can be placed on a reflective surface to improve accuracy.
–
Allow the tape to acclimate to the surface’s temperature before taking a measurement.
ƒ
Steam, dust, smoke, and/or vapors can prevent accurate readings by obstructing the unit’s optics
ƒ
Eye protection may be required to protect the operator from harm
Calibration
Inspectors should question noticeably high or low readings. Previously dropped or damaged instruments may
give inaccurate readings. Inspectors can set an accuracy benchmark by taking spot measurements around the
target area. This helps identify if a reading is inaccurate, or outside the specified range. Having other
instruments on hand can also help determine which readings are either extremely high or extremely low.
Inspectors should never attempt to calibrate IR thermometers. Instead, they should be calibrated each year
by the manufacturer or a 3rd party laboratory to ensure the most accurate results.
18.3 Air Temperature, Humidity, & Dew Point
Measuring Air Temperature, Humidity,
and Dew Point
Like surface temperature, high and low air
temperatures alone can adversely impact the
coating application process. Nonetheless, air
temperature is commonly measured alongside
relative humidity as both conditions must be
measured to calculate the dew point. Identifying the
dew point is important as moisture formation can
negatively impact the coating installation process by
triggering the formation of flash rusting during abrasive blast operations and by preventing solvent from
evaporating from the coating film leading to defects. There are two primary methods that inspectors use to
measure air temperature, relative humidity and dew point. The first is to use a sling psychrometer or whirling
hygrometer and then reference a psychrometric table, calculator or app, and the second is to use a digital dew
point meter.
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Chapter 18: Measuring Environmental Conditions
Sling Psychrometer
Overview
Sling psychrometers and whirling hygrometers are configured a little differently, but both perform the same
role and operate in a similar fashion. Sling psychrometers and whirling hygrometers both contain two
thermometers. The first thermometer, called a “dry-bulb,” measures the ambient air temperature. The second
thermometer contains a woven cotton filament or wick, which is wetted prior to use -- hence the name “wetbulb.” The “wet-bulb temperature” represents the heat loss from the evaporation of water in the wick. The
faster the water evaporates, the more cooling occurs, resulting in lower wet-bulb temperature.
Once the dry- and wet-bulb temperatures have been established, both the relative humidity and the dew
point can be calculated, first by calculating the wet-bulb depression. Then by using both the wet-bulb
depressions and the dry-bulb temperatures with a psychrometric table, calculator, or a mobile application.
While sling psychrometers are less efficient than their digital counterparts, they are intrinsically safe and can
be used in confined spaces or other environments in which electronic equipment is not suitable.
Standards
The following standard describes the selection and/or use of Psychrometers:
ƒ
ASTM E337 Standard Test Method for Measuring Humidity with a Psychrometer (the Measurement of
Wet- and Dry-Bulb Temperatures)
–
This method details how to determine the humidity of atmospheric air by means of wet- and dry-bulb
temperature readings and incorporates the use of the sling psychrometer. The methods described
are applicable within an ambient temperature range of 0-50°C (32-122°F), wet-bulb temperatures not
lower than 1°C (33.8°F) and restricted to ambient pressures not differing from standard atmospheric
pressure by more than 3%.
Note that additional standards may also be available for your region.
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Chapter 18: Measuring Environmental Conditions
Method of Operation
1. Saturate the wick with clean water
2. With the fin of the hygrometer facing in the direction you are going to whirl the instrument, whirl at a
moderate speed (2-3 revolutions per second) for 20 to 40 seconds
3. Read the wet-bulb temperature
ƒ
The wet-bulb temperature will begin to change when the air movement from whirling, stops
4. Repeat Steps 2 and 3 until the wet-bulb temperature stabilizes
5. Record the temperature from the wet-bulb and dry-bulb thermometer
6. Calculate the wet-bulb depression by subtracting the wet-bulb temperature from the dry-bulb temperature
7. Determine relative humidity and dew point by referencing a psychrometric table or a dew point calculator
ƒ
To use a psychrometric table:
–
Locate the dry-bulb temperature in the vertical column
–
Locate the wet-bulb depression value in the horizontal column
–
Locate where the two temperatures intersect
–
Record the relative humidity or dew-point temperature
–
Depending on the table being used, some will list one condition and others will list both
8. Record the relative humidity and dew point temperature
Important
Both relative humidity and dew point temperature may vary with barometric pressure. The
differences are generally small, and although many tables (calculated at different pressures) are
provided in a typical book of tables, it is reasonably accurate to use tables based on a barometric
pressure equivalent to 30 inches of mercury. For absolute accuracy, determine the actual
barometric pressure and use the appropriate table to determine relative humidity and dew
point temperature.
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Chapter 18: Measuring Environmental Conditions
Usage Tips & Common Errors
Usage Tips
To help ensure that accurate measurements are
performed:
ƒ
Whirl the psychrometer as close to the work area
as possible
ƒ
Face the wind and step back and forth a few
steps when whirling
–
ƒ
This will prevent your body from adversely
affecting readings
Verify that the wet-bulb temperature is lower than the dry-bulb temperature
–
ƒ
If both thermometers are displaying the same temperature, then the wick has not been wetted
sufficiently
Do not use when the temperature is near or below the freezing point
–
The psychrometer will not provide a reliable reading
Common Errors
If you are experiencing some issues with getting an accurate reading, here are some common errors to look
out for:
ƒ
Check to see if the wick is firmly placed over the end of the thermometer before whirling
ƒ
Not whirling the psychrometer long enough to reach equilibrium (stabilize)
ƒ
Failure to thoroughly wet the wick
ƒ
Holding the psychrometer too close to the body
ƒ
Taking too long to read the thermometers
ƒ
Misreading the thermometers, psychrometric charts, or calculators
ƒ
Touching the bulb ends with your hands while reading the measurements
ƒ
Facing away from the breeze
ƒ
Gently slinging the psychrometer
–
The necessary RPM will not be reached
Mentor Tip
Read the thermometers very carefully. Slight differences in the temperature readings can cause
significant differences in the calculated dew point temperature.
Calibration
To help ensure that the sling psychrometer provides accurate readings, the inspector should check that both
thermometers are providing the same readings by:
1. Removing the two thermometers
2. Placing them in a cup of room temperature water for 3-4 minutes
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Chapter 18: Measuring Environmental Conditions
3. Removing the thermometers
4. Compare the thermometers reading to verify they match
The two thermometers should have identical readings. If the readings are not identical, replace the
thermometers. The sling psychrometer must have two thermometers that tread the same in a like
temperature environment.
Determining the Delta T (TΔ)
In addition to verifying that each of the individual
environmental conditions are within the specified
range, the inspector also needs to continuously
monitor the temperature difference between the
surface temperature and dew point temperature,
which is referred to as the Delta T value. Dew point is
the temperature at which atmospheric air becomes
saturated with water, and there is a risk of moisture
forming on the substrate. On most projects, the
specification will require that the surface temperature is at least 3°C or 5°F above the dew point.
The are several methods that can be used to determine if there is a minimum 3°C (5°F) temperature gap. For
example, you could use a Surface Thermometer and Sling Psychrometer, which involves:
1. Measuring the dry-bulb (air temperature) and wet-bulb temperature using a sling psychrometer.
2. Using a psychrometric table/calculator/mobile app to calculate the dew point temperature.
ƒ
When using a psychrometric table, calculate the wet-bulb depression first
3. Measuring the surface temperature using a contact thermometer or an IR thermometer.
4. Subtracting the Dew point Temperature from the Surface Temperature.
ƒ
Verify that there is at least 3°C (5°F) difference
Environmental Conditions
Time
Time
Time
Time
 Yes  No
 Yes  No
 Yes  No
 Yes  No
Air Temperature
Wet Bulb Temperature
Relative Humidity
Surface Temperature
Dew Point
Surface temp ≥ 3°C (5°F)
Wind Speed
A quicker and simpler method involves the use of a digital dew point meter.
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Chapter 18: Measuring Environmental Conditions
Digital Dew Point Meter
Overview
A digital dew point meter is a multi-purpose
instrument that measures relative humidity and air
temperature and then calculates the dew point
temperature. Most units can also measure surface
temperature. It is important to highlight that digital
hygrometers possess fewer capabilities than digital
dew point meters. Digital hygrometers can measure
relative humidity and air temperature, but they
cannot calculate the dew point.
Digital dew point meters have a range of advantages over their manual counterparts. They:
ƒ
Can calculate the spread between the dew point and surface temperatures
ƒ
Can provide automatic data collection
ƒ
Store, transmit, and automatically graph data (some models)
ƒ
Can be programmed to alarm if conditions are outside of the specified parameters
ƒ
Can be used as remote data logging monitors
Standards
The following standard describes the use of Hygrometers (digital dew point meters):
ƒ
ASTM D4230 Standard Test Method of Measuring Humidity with Cooled-Surface Condensation (Dew
Point) Hygrometer
Note that additional standards may also be available for your region.
Method of Operation
1. Open the sensor’s protective shutter and press the “on” button
2. Expose sensor to the environment and then touch to the surface to measure the surface temperature
3. Wait 30 seconds to a minute for the device to stabilize
ƒ
After stabilizing, the air temperature and relative humidity are displayed.
ƒ
Temperature readings are displayed in either Celsius or Fahrenheit. Users may switch between the two
as needed when readings are taken.
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Chapter 18: Measuring Environmental Conditions
4. Press the “hold” button once to freeze the displayed readings and stop taking measurements. To continue
taking readings, press the “Hold” button again.
5. Read and record the results
ƒ
A significant advantage of digital dew point instruments is the ability to store readings in memory and
transfer them to other devices. Press the “record” button to save a dataset into memory.
Important
Inspectors should familiarize themselves with the process of storing and transferring the
recorded readings as it can very between models.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Allow the meter to acclimate prior to use and
when moving between starkly different
environments
ƒ
Keep fingers away from the sensors
–
Otherwise, the airflow may be obstructed, or
body heat may be added, both of which can
cause inaccurate readings
ƒ
Lift the meter between surface temperature readings instead of dragging
ƒ
Use light contact between the meter and surface
ƒ
Keep the sensors clean, dry, and free of other contaminants
ƒ
Allow readings to stabilize
Calibration
Inspectors should routinely question readings when highs and lows are outside known parameters. However,
it is important to keep in mind that there can be a significant difference between the local weather and jobsite
conditions. Most inaccurate readings occur when the instrument has not been given sufficient time to adjust
to the climate, i.e., moving from an office environment to a cold exterior setting. Erroneous readings are likely
due to calibration or equipment malfunction and should be flagged for re-calibration. Dew point meters
typically arrive from the manufacturer already calibrated, at a level of quality that meets the National
Calibration Standard. If they need to be calibrated while in the inspector’s care, this calibration must be
performed by an independent lab or by the manufacturer.
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Chapter 18: Measuring Environmental Conditions
Logging
Some digital dew point meters can be used as
remote data logging monitors in addition to working
as a hand-held meter. In other words, they are
capable of independently performing and recording
measurements. These meters can be placed in a
carefully selected location on the jobsite and will
then automatically measure the environmental
conditions at the selected time interval. Most meters
have integrated magnets that allow them to be
attached directly to the asset being coated. If conditions move outside the selected ranges (e.g., 15°C – 32°C),
the meter will alert the inspector through a visual or auditory alarm. These devices also store the readings,
which can then be sent to third-party devices through Wi-Fi, Bluetooth, or direct access and attached to Daily
Reports. These digital dew point meters are ideal for providing evidence that environmental conditions
remained within the specified limits throughout the entire project.
Important
It is important to note that conditions can vary around a jobsite, and measurements should be
taken where actual work is being performed.
18.4 Wind Speed
Measuring Wind Speed
Wind speed is the measure of the natural motion of
air moving past a certain point. High winds can have
a range of adverse impacts on the coating
application process. High winds can cause dry spray,
blow dust and debris into the coating film, and
accelerate curing, causing incorrect film formation.
Inspectors commonly measure wind speed with the
use of an anemometer, sometimes referred to as a
wind meter. There are two different types of
anemometers that are commonly used: fan type wind meters and hot-wire wind meters.
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Chapter 18: Measuring Environmental Conditions
Wind Meter (Anemometer)
Overview
An anemometer, otherwise known as a wind speed
meter, is an instrument utilized to measure wind
speeds. Wind speeds are commonly measured to
determine if conditions are appropriate for coating
application. Fan-type wind speed meters measure
wind speed by monitoring the rate that the fan spins
when the wind moves through the instrument. Both
analog and digital versions are available. Analog
wind meters are less expensive than digital wind meters but are typically more difficult to use.
Hot Wire Wind Meter
Some wind meters use ‘hot-wire’ technology instead of a fan to measure wind speed. As the name indicates,
hot-wire wind meters contain a thin heated wire. These meters determine the wind speed by measuring the
amount of heat lost from the heated wire. The more heat that is lost, the higher the wind speed.
Method of Operation (Fan)
To measure wind speed with a fan-type wind meter:
1. Remove the protective cover and turn the meter
on (when required)
2. Position the meter so the opening faces the wind
and the display is visible
3. Hold the instrument at arm’s length so the air
flows without obstruction from your body
4. Read and record the results
Method of Operation (Hot-wire)
To measure wind speed with a hot-wire wind meter:
1. Turn on the meter and select the suitable measurement mode
2. Open the protective cover, so the sensor is exposed
3. Position the meter so the opening faces the wind and the display is visible
4. Hold the instrument at arm’s length so that the air flows through without obstruction
5. Read the results on the display
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Chapter 18: Measuring Environmental Conditions
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Face the wind when using the instrument
–
If the inspector is not facing the wind, the
reading won’t be accurate
ƒ
Hold the instrument away from the body as it can
act as a windshield
ƒ
Avoid using fan type wind meters when the wind
is too strong
–
ƒ
Take care to protect the wire (hot-wire only)
–
ƒ
This will wear out the roller bearing
Store the instrument in the protective sheath when not in use
Select the correct unit of measurement:
–
Miles per hour (mph)
–
Feet per second (ft/s)
–
Kilometers per hour (kph)
–
Meters per second (m/s)
Calibration
Inspectors should always question the reading if it does not appear to be the actual wind speed. It is helpful to
check the local weather forecast for the day as this provides benchmark ranges for the day. As with all things
in industrial coating operations, a little common sense will go far. If you can feel a breeze, but the meter is not
registering a wind speed, there is probably something wrong with the instrument, and it should be checked.
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Chapter 18: Measuring Environmental Conditions
Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. The contractor’s sling psychrometer gives a different reading than your digital dew point
meter. What would you do first as an inspector?
A. Verify calibration of both instruments
B. Accept the digital dew point meter reading
C. Shut down the work
D. Accept the sling psychrometer reading
2. Where should surface temperature readings be taken?
(Select all that apply)
A. Only in direct sunlight
B. Only in the shade
C. At the actual work location
D. At areas that are likely to be hotter or colder than the normal
E. On areas of the structure that are exposed to high wind
3. What is the temperature at which moisture condenses on a surface called?
A. Relative humidity
B. Dew point
C. Delta T (temperature)
D. Surface Temperature
E. Air Temperature
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Chapter 18: Measuring Environmental Conditions
Self-Study Review
Answer the following questions for additional practice. To check your responses, refer to the
Answer Key in the Reference tab.
1. What are some common errors when using a digital dew point meter?
2. Which of the following would be appropriate to add to a sling psychrometer?
A. Red spirit
B. Seawater
C. Distilled water
D. Mercury
3. List the steps to determine the relative humidity and dew point using the sling
psychrometer:
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Chapter 19: Soluble Salt Detection
Chapter 19:
Soluble Salt Detection
19.1 Introduction
Learning Objectives
By the end of Chapter 19, students should be able to:
1. Accurately collect and measure soluble salts using different collections and test methods.
Non-Visible Contaminants
Chlorides are usually the primary focus of soluble
salt testing, but select projects will also require the
inspector to test for sulfates, nitrates, and ferrous
ions. The detection and removal of these soluble
salts are important as they can accelerate the
corrosion and cause the coating film to break down
through blistering and disbondment. The inspector
typically tests for soluble salts prior to the core
surface preparation activities of power tool cleaning
and abrasive blasting. Although it can also be performed after the surface preparation operations are
complete, but before the primer is applied. Testing at this later stage is undertaken to determine if soluble
salts were introduced to the surface during the surface preparation process.
The inspector must know the specification’s requirements prior to carrying out soluble salt testing. The
specification should prescribe which test method to employ, the number of measurements that should be
taken, the location of the measurements, specific salts to be tested for on the surface (determined by the test
method), the units of measurement to use, and the remedial action (when required). Further, as there is no
“industry standard” for tolerable levels of chemical contaminants, the project specification must indicate the
maximum concentration of soluble salts that can remain on the surface and be safely coated over.
For example, "Surfaces shall be tested for soluble salts prior to commencement of surface preparation."
Chloride levels shall be 10 μg/cm² or less, as determined using the “Chlor-Test” method A for chlorides. At
least 3 tests shall be performed in each area of 10 m2 (100 ft2). If any single test result is greater than 10 μg/
cm², the area shall be water-washed and reblasted. It shall then be retested prior to coatings application, and
the same limits shall apply.”
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Chapter 19: Soluble Salt Detection
Test Methods
Testing for soluble salts focuses on either verifying
that the concentration of soluble salts is below the
permissible limit or simply detecting if they are
present. There are a range of different test methods
and corresponding instruments available to perform
soluble salt testing.
1. Collecting the Sample
To test for the presence or concentration of soluble
salts, a sample needs to be collected from the surface. Soluble salts are susceptible to being dissolved in
liquids, especially water. As a result, if a liquid is applied to the surface and soluble salts are present, they
should dissolve into the liquid. This liquid can then be extracted, and a sample obtained. The challenge for an
inspector is then controlling this collection process. Two different test methods are commonly used to collect
this sample, including:
1. Disposable, adhesive latex patch or a reusable, flexible patch with magnetic ring
2. Disposable, adhesive latex sleeve
Mentor Tip
Salt tests are extremely sensitive, and as such, clean latex or nitrile gloves should be worn during
the collection of salts to prevent contamination of the surface
2. Analyzing or Testing the Sample
Once a sample has been collected from the surface,
it then needs to be tested and analyzed for the
presence of soluble salts and/or their concentration.
There are a number of test methods that are
commonly used in the field, including:
1. Kitagawa® Chloride Titrator Tube
2. Bresle® Kit Drop Titration for Chloride
3. Conductivity Meters
There are also three test methods that combine the collection and analysis process, they are:
1. Potassium Ferricyanide Test
ƒ
Tests for ferrous ion salts
2. Salt Contamination Meters
2
ƒ
Tests for the concentration of salts
ƒ
Referred to as the Saturated Special Filter Paper With Concentric Ring Conductivity Meter by SSPC
Technology Guide 15
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Chapter 19: Soluble Salt Detection
3. CSN Test kits
ƒ
Tests for the presence of chloride, sulfates, and nitrates using a range of different test methods
Test Principles
The testing of the collected sample occurs through two different principles. The first principle is that soluble
salts are conductive, and the second principle is that soluble salts can be reactive.
ƒ
Conductive
Water-soluble salts increase the electrical conductivity of demineralized or deionized water. For example,
saltwater will conduct electricity better than distilled water. Therefore, if an inspector samples the surface
with demineralized water and then tests the water sample, an increase in electrical conductivity indicates
that the water has extracted salts from the surface. The exact conductivity can then be recorded and
further used to calculate the concentration of salts on the surface. It is important to highlight that
conductivity testing will not be able to tell the inspector what type of salt is on the surface, only that there
is some type of water-soluble salt that is causing the electrical conductivity of the water to increase.
ƒ
Reactive (Specific Ion Detection)
There are a range of test methods that can identify whether a specific type of water-soluble salt is on the
substrate. Specific salts are detected by triggering a visible chemical reaction. How the reaction is
triggered depends on if the inspector is testing for chlorides, nitrates, or sulfates. As an example, silver
chromate can be used to measure chloride concentration. When the silver chromate inside a titration
tube encounters the chloride salts within a collected sample, it will react and form silver chloride. This
reaction is visible within the titrator tube as the material changes from pink to white as the silver chloride
forms. If no chloride ions are present, then no color change will occur. Depending on the test method, the
amount of color change that occurs can be measured and used to determine the concentration of soluble
salts.
Mentor Tip
Sodium chloride (NaCl), commonly known as table salt, is typically the focus when testing for
soluble salt contamination. As the proportion of NaCl to total atmospheric salts is relatively
consistent in the environment, both the methods described above can provide an indication of
the amount of contamination with corrosion potential on the substrate.
19.2 Test Instruments
Test Methods for Collecting and Analyzing
Soluble Salts
As discussed, there are a range of test methods that
can be employed to collect a sample from the
substrate and then analyze it for the presence of
soluble salts. This chapter focuses on the six
methods commonly performed in the field.
Depending on the project and the region the project
is being carried out in, other methods may also be
specified. In this section, the Bresle Patch Method is
paired with the Conductivity Meter.
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Chapter 19: Soluble Salt Detection
Bresle Patch: Overview
A Bresle Patch is used to collect a sample from the
substrate that can then be tested for the presence of
soluble salts and their concentration. This test
involves the use of either a disposable, adhesive
latex or polyurethane cell or a reusable magnetic
patch. These cells/patches can adhere to the surface
in almost any position, including vertical, horizontal,
and uneven surfaces.
When performing the Bresle Patch Test, the latex cell is applied to the test area, and then a specified volume
of deionized water or another approved solution is injected into the space between the patch and the
substrate. If soluble salts are present on the surface, they will dissolve in the solution. This solution is then
extracted using a syringe, and its contents are tested to determine if soluble salts are present and their
concentration. How the sample is tested will be discussed later in this chapter.
Standards
The following standards describe the Bresle Test Method
ƒ
ISO 8502 Preparation of Steel Substrates Before Application of Paints and Related Products – Tests for the
Assessment of Surface Cleanliness.
–
ƒ
Part 6: Extraction of Soluble Contaminants for Analysis – The Bresle Method.
SSPC Guide 15, Retrieval and Analysis of Soluble Salts.
–
Method A1: Patch Cell Retrieval Method.
Additional standards may be available for your region.
Method of Operation
The following information is a general description of how to collect a sample from the substrate using a Bresle
Patch. Always refer to the project’s specification, referenced standard, and manufacturer’s instructions for
more specific directions.
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Chapter 19: Soluble Salt Detection
Step One: Prepare the test site
Prior to testing, the inspector must verify that the substrate is dry and that there is no loose material on the
surface area. If the surface is not properly prepared, then the cell’s frame will not fully adhere to the surface,
and later in the process, the added solution may leak. Note that a stiff nylon bristle brush can be used to
remove any dust or abrasive particles from the selected test area.
Step Two: Prepare the extraction fluid
Fill a syringe with 3 ml of deionized water. Draw the water into the syringe, making sure to draw in more than
is needed. Next, hold the syringe upright, tap the syringe, and then discard the excess liquid by slowly
depressing the syringe plunger until the desired quantity is obtained (e.g., 3 ml). This procedure will remove
any trapped air from within the syringe. Record the actual volume of sampling liquid to be used. Note that
while the volume of liquid is typically 3 mls, the amount required will be specific to the manufacturer as it
correlates with the sampling area within the patch.
Note that it is vital that the extraction fluid that is injected into the Bresle patch is free from soluble salts.
Otherwise, measurements and subsequent readings will be inaccurate. The common types of extraction
liquids that used are the specialized extraction fluid supplied by the manufacturer or deionized, distilled,
or demineralized water.
Important
If a conductivity meter will be used to analyze the collected sample, then it is good practice to
obtain a blank/base conductivity measurement. This process involves placing the extraction
fluid into the meter prior to injecting it into the patch. The inspector then records the readings
and returns the liquid to the syringe.
Step Three: Adhere the Bresle Patch to the test area
To tightly adhere the latex patch to the test area:
1. Peel off the label from the adhesive side of the Bresle Patch and discard it. This will expose the adhesive.
2. Carefully press the center of the non-adhesive side of the cell to “punch-out” the foam square (or circle in
the case of the BresleSampler®) to create a “void” area. This foam square can also be discarded.
3. Attach the Bresle Patch to the test surface (adhesive side down).
4. Press firmly around the foam border of the Bresle Patch to ensure there is a good seal on all sides.
To tightly adhere the reusable patch (e.g., PosiPatch) to the test area:
1. Turn the patch and magnetic ring upside down.
2. Place the patch into the magnetic ring, ensuring the arrows align with the injection port.
3. Carefully place the magnetic ring on the steel surface.
ƒ
When used on vertical surfaces, position the port between the 2 o’clock and 10 o’clock points before
attaching the ring to the surface.
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Chapter 19: Soluble Salt Detection
Step Four: Evacuate the air from the Bresle Patch
Insert the needle of an empty 5 ml syringe into the
cell through the spongy foam perimeter. The needle
should be visible through the semi-translucent top
but should not pierce it. Holding the syringe at a 30°
angle can help to position the syringe correctly.
Next, pull back the syringe’s plunger to remove the
air from inside the cell. Removing the air will help to
prevent over-pressurization of the cell during the
sample collection. As the air is being removed, a
vacuum may be created within the cell. A vacuum is visible by the top of the cell being sucked in towards the
test surface. Depending on the quality of the seal around the foam border, this vacuum may or may not hold.
It is okay if the cell does not maintain a vacuum. Next, carefully remove the syringe needle from the cell by
sliding it back through the foam perimeter. Once the syringe’s needle is free, push the syringe’s plunger to
release the air. Note that when using reusable patches like DeFelsko’s PosiPatch, air is automatically removed
through the air-permeable membrane.
Step Five: Inject the fluid and agitate the sample
Carefully slide the syringe needle through the foam border until it is visible through the semitranslucent top.
Next, slowly inject the fluid from the syringe into the cell and then carefully slide the needle back into the foam
border. Do not remove the needle from the cell; it should be left in the spongy perimeter. Next, gently
massage the face of the cell using moderate pressure for 15 - 20 seconds or for the time specified. This
“agitates” the fluid inside the cell and helps to extract the soluble salt contaminants. Note that reusable
patches have a designated injection port. If using PosiPatch, inject all of the water into the cell.
Step Six: A Collect the sample
Slide the syringe needle back into the cell and then draw out most of the solution. Slowly inject the solution
back into the cell and agitate it again. Repeat this procedure a minimum of 4 times (per ISO 8502-6). After the
final time, evacuate as much of the fluid from the Bresle Patch as possible using the syringe. Completely
remove the syringe needle from the cell by sliding the needle back through the foam border.
Next, empty the contents of the syringe into a small plastic beaker, container, or vial. Alternatively, if a
conductivity meter is used to test the sample, it can be transferred straight from the syringe to the meter’s test
cell. If additional samples are going to be collected, the inspector must thoroughly flush the syringe and
needle with distilled or deionized water and have a separate container ready. Otherwise, the samples can be
cross-contaminated.
Step Seven: Test the sample
The collected sample can now be tested for the presence of soluble salts and their concentration using a
conductivity meter. This process will be discussed later in this chapter.
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Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
To prevent contamination, always extract
measurement liquid directly from the deionized/
demineralized water container or the bottle of
solution provided by the instrument
manufacturer
–
ƒ
Also, never reinsert the used needle back
into deionized water or manufacturer's
solution to avoid contamination
Never insert the needle into the transparent portion of the patch or the bottom of the patch
–
This will cause the liquid solution to leak at both locations.
ƒ
Check that the cell has properly adhered to all four sides of the patch.
ƒ
Avoid contamination of the collected sample by:
ƒ
–
Rinsing all materials in clean distilled water prior to performing the test.
–
Never discard liquid back into the container when refilling the syringe.
–
NEVER touch any part that contacts the test water with your bare hands; wear gloves instead!
Check the units of measurement on both the syringes and extraction fluid.
–
ƒ
Items from different test kits are sometimes thrown together in the field, resulting in mixed units.
Handle syringes with care.
–
Syringes are sharp, and care should be taken to avoid puncture wounds, especially with aerated
contents.
Calibration
Latex and polyurethane Patches are single-use items.
Conductivity Meter: Overview
A conductivity meter sometimes referred to as a
conductivity probe, is an instrument that allows the
inspector to test a collected sample for the presence
of salt contamination (non-salt specific). Conductivity
meters are lightweight, hand-held devices and are
produced by a range of manufacturers. When in use,
a few drops of the collected sample are dropped into
the test cell or sensor of the device, which will then
measure its conductivity. Alternatively, some models
of conductivity meters can also be immersed within the sample.
The more conductive the solution is, the higher the concentration of soluble salts. Some conductivity meters
will also automatically convert conductivity readings to display the surface density of soluble salts (mg/m2 or
µg/cm2), negating the need for the inspector to perform a manual calculation when specified.
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Standards
The following standards describe the use of conductivity meters:
ƒ
ISO 8502 Preparation of Steel Substrates Before Application of Paints and Related Products – Tests for the
Assessment of Surface Cleanliness
–
ƒ
Part 9: Field Method for the Conductometric Determination of Water-soluble Salts
SSPC Guide 15, Retrieval and Analysis of Soluble Salts
–
Method 5.2: Field Measurement of Conductivity
Additional standards may be available for your region.
Method of Operation
The information below is a general description of
how to test a collected sample using a conductivity
meter. Refer to the project’s specification,
referenced standards, and manufacturer’s
instructions for more specific directions.
Step One: Turn on the meter and verify the settings
Turn on the conductivity meter by holding the power
buttons for several seconds. The power button is
typically located near the digital display. Next, verify that the settings are correct, paying particular attention
to the units of measurement (e.g., μS/cm or mS/m) and the measurement mode if more than one is available.
For the more sophisticated conductivity meters, the batch number, storage mode, and paired devices can also
be verified.
Step Two: Verify the accuracy of the meter
Select the calibration option on the meter and remove the sensor’s protective cap/cover. On some meters,
there is a designated calibration button, and on others, it will be located within the menu. Once selected, “CAL”
will typically appear on the display. Next, fill the test cell with the manufacturer’s provided calibration
standard, taking care to avoid the formation of bubbles. A calibration standard is a solution with a known
conductivity, for example, 1413 µS/cm. Close the protective cover (if present) and press and hold the
calibration button.
After the calibration is complete, a reading will appear on the display. The reading should be within the
tolerance of the calibration standard tested. Finally, rinse the sensor with deionized water. Note that this
process is sometimes performed with deionized water to generate a blank conductivity measurement. Select
gauges also need to be “zeroed” using deionized water prior to use. Consult the manufacturer's instructions
regarding the necessity to zero the gauge
Step Three: Measure the conductivity of the sample
Switch from calibration mode to measurement mode. On some meters, there is a designated measurement
button, and on others, the option can be located within the menu. Next, measure the sample through the
drop sampling method or the immersion method.
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Chapter 19: Soluble Salt Detection
ƒ
Drop Sampling
When using the drop sampling method, use a syringe or pipette to transfer the collected sample into the
test cell. Take care to avoid bubbles forming as they can trigger inaccurate readings. Next, close the
protective cover (if present) and wait for the reading to appear on the display and stabilize. It can take up
to 5 seconds for the sample to stabilize. Note that if the sample was collected using the Bresle Patch
method, the syringe that was used to remove the sample from the cell can be used to transfer it straight to
the conductivity meter.
ƒ
Immersion
When using the immersion sampling method, immerse the sensor within the collected sample and stir
gently 2 to 3 times. Take care to avoid spilling any of the samples and to avoid immersing the meter past
the maximum immersion level line marked on the body of the sensor. Next, wait for the reading to
appear on the display and stabilize. Again, it can take up to 5 seconds to stabilize. Then place the
conductivity meter on a flat, horizontal surface. Note that not all conductivity meters can be immersed,
and that this method requires a larger sample to be collected.
Step Four: Hold and record the results
Press the hold button (often symbolized by “+”) to retain the readings on the display until they can be
recorded. The reading should display both the conductivity of the solution and the temperature of the
solution. Some meters will also automatically calculate the surface density of soluble salts.
Once the reading has been recorded, verify that it is in conformance with the specification. If the
concentration of soluble salts is above the specified limit, then the deviation should be reported, and
remediation tasks will need to be performed per the specification’s requirements (E.g., pressure washing the
area). When the inspector has finished performing the measurements, the conductivity meter should be
turned off, rinsed with deionized water, and the sensor cap replaced.
The inspector should always review
the manufacturer’s user manual when
working with new instruments. Each
instrument can display readings
differently, including the symbols they
use. In this example:
t = Test duration
T2 = Sample temperature
Δy= The change in conductivity. The
initial background measurement (γ1)
is automatically subtracted from the
final measurement (γ2).
Sample
Temperature
Density of
Soluble Salts
Test Duration
Change in
Conductivity
ρA =The surface density of soluble salt
expressed as sodium chloride
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Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Rinse all materials in clean distilled water to
ensure they are not contaminated.
ƒ
Never touch any equipment with their bare
hands that will come in direct contact with the
collected sample.
–
Salt from the skin can cause reading errors.
ƒ
Ensure the battery is sufficiently charged or replace depleted batteries
ƒ
Be aware that some gauges can only operate within certain temperature ranges
ƒ
Check that salt concentrations are not outside the meters operating parameters
–
A meter with a resolution of 0.1 μS/cm in the range of 0-200 μS/cm is required.
Calibration
All conductivity meters should come with a Certificate of Calibration. Once in service, conductivity meters are
typically re-calibrated every 12 months by either the manufacturer or an authorized lab. Verification of
accuracy can also be performed by the inspector, per the manufacturer’s instructions.
Latex Sleeve & Titrator Tube
In this section, the Latex Sleeve is paired with the
Titrator Tube. Manufacturers typically sell this
collection and testing method together as a
complete kit for ease of use in the field.
Latex Sleeve: Overview
The latex sleeve is employed to collect a sample from
the substrate that can then be tested for the
presence of soluble salts and their concentration.
Latex sleeves are designed to be used on vertical,
horizontal, and overhead surfaces. When
performing the latex sleeve test, the specialized
solution is poured into the sleeve, and then it is
adhered to the substrate. Next, the sleeve is held up
and agitated for a specified duration. If soluble salts
are present on the surface, they will then dissolve in the solution. The sleeve is then removed and placed in a
special holder. The contents of the sleeve can then be tested to determine if soluble salts are present and
their concentration. How the sample is tested will be discussed later in this chapter.
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Chapter 19: Soluble Salt Detection
Standards
The following standard describes how to extract a sample from the surface using the sleeve method:
ƒ
SSPC Guide 15, Retrieval and Analysis of Soluble Salts
–
Method A2: Sleeve Retrieval Method
Additional standards may be available for your region.
Method of Operation
The information below is a general description of
how to collect a sample from the substrate using the
latex sleeve method. Always refer to the project’s
specification, any referenced standards, and
manufacturer’s instructions for more specific
directions.
Step One: Identify the test site and verify that it is
properly prepared
Prior to performing the test, the inspector should also verify that the substrate is dry and that there is no loose
material present. If the surface is not properly prepared, then the sleeve may not adhere correctly and can fail
or allow surrounding contaminants to enter the sleeve.
Step Two: Prepare the latex sleeve
Next, remove the cap of the pre-measured extraction solution and pour the entire contents into the sleeve.
Peel the pressure-sensitive, protective backing from the latex sleeve to expose the adhesive. Then, remove
the air from the latex sleeve by squeezing it between fingers and thumb. Care should be taken to avoid spilling
any of the solution while evacuating the air from the latex sleeve.
Step Three: Adhere the sleeve and agitate the solution
Adhere the latex sleeve to the surface by attaching the adhesive end of the latex sleeve to the test area. Press
firmly around the perimeter of the contact area to ensure there is a good seal between the surface and the
sleeve. Next, with one hand, lift and hold the free end of the latex sleeve upright so that the extraction solution
comes into contact with the test surface. On the other hand, use your fingers to massage the solution
(through the latex sleeve) for at least 2 minutes. This helps to extract the soluble salts from the surface into
the solution. Extending the massage time up to 6 minutes will result in increased extraction efficiency if
allowed by the specification or the applicable standard.
Step Four: Collect the sample
Position the latex sleeve so that the extraction solution returns to the bottom. For overhead or vertical
surfaces, gravity will put it there. For horizontal surfaces, the inspector will need to slide their fingers along the
outside of the latex sleeve and push all of the solution into the closed end of the sleeve before removing it
from the surface. Next, carefully peel the latex sleeve from the test surface and place it in the designated
holder (typically a hole in the lid of the kit), with the open end of the sleeve facing up.
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Step Five: Test the sample
The collected sample can now be tested for the presence of soluble salts and their concentration by inserting
the titration tube into the sleeve. This process will be discussed later in this chapter.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Carefully consider the testing environment
–
Is debris or foreign material likely to fall into
the sample at your chosen location?
ƒ
Take care while evacuating the air from the latex
sleeve to avoid spilling the solution.
ƒ
Lift the sleeve at the right angle so that the
solution is in contact with the substrate.
ƒ
Be aware that on a horizontal surface, the solution will pool at the opening.
–
ƒ
Twist the sleeve prior to removal to help ensure that all the solution is collected.
Verify that all the edges are sealed so when the sleeve is lifted, some of the solution leaks out.
–
Note that the adhesive sleeve may not adhere as well to rusted surfaces.
Usage Calibration
Calibration is not required as latex sleeves are a single-use item. However, it should be noted that the quality
of the sleeves can vary between manufacturers.
Titration Tubes: Overview
A titration tube sometimes referred to as a detector
tube, is an instrument that allows an inspector to
test a collected sample for the presence of chlorides
and their concentration. This test method involves
breaking off the ends of the titration tube and then
placing it into the collected solution. The solution will
then rise up through the reagent within the tube via
capillary action. If chloride ions are present in the
solution, they will react with the silver chromate
(reagent) within the tube and create silver chloride. This chemical reaction is then displayed as a color change
within the tube. A coating inspector can then identify the concentration in parts per million (ppm) based on
how much of the material changes color. Note, there is a separate titration tube that can be used to detect
sulfates.
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Chapter 19: Soluble Salt Detection
Standards
The following standards describe the use of titration tubes.
ƒ
SSPC Guide 15, Field Methods for Extraction and Analysis of Soluble Salts on Steel and Other Nonporous
Substrates
–
Method 5.4: Field Detection of Chloride Ion by Ion Detection Tube
Additional standards may be available for your region.
Method of Operation
The information below is a general description of
how to analyze a collected sample using chloride
titration tubes. Refer to the project’s specification,
referenced standards, and manufacturer’s
instructions for more specific directions.
Step One: Prepare the titration tube
Using the metal tube snapper, break off both ends of
the titration tube. Both ends of the tube should be
“open.” Take care to avoid touching either end of the tubes, as this can contaminate the instrument. Note that
the ends of the tube will be very sharp, so care is required to avoid injury.
Step Two: Place the tube into the sample
Locate the bottom of the tube as indicated by the arrow and smallest numbers. Place the “open” titration tube
into the latex sleeve (or another collected sample) bottom down. Note that the arrow indicates the direction
that the solution will flow through the tube (upwards). Next, allow the tube to remain in the solution for at
least 90 seconds or until the capillary motion has pulled the sample solution to the top of the tube. The cotton
filaments at the top of the titration tube will turn from white to amber color when the sample has reached the
top. Disregard any yellow coloring inside the tube during the test. If the sample does not begin to travel up the
titration tube within 30 seconds, an aspirator bulb can be used to assist the movement of the sample.
Step Three: Examine the color change within the tube
Remove the titration tube from the latex sleeve as soon as the cotton filaments at the top of the tube turn
from white to amber. Next, read the value on the tube by locating where the pink and white-colored material
interfaces. The pink coloration inside the tube is normal, while the white coloration indicates the presence of
chloride. As a result, the value at the pink/white color interface represents the amount of chloride present in
the test solution. This value is expressed in parts per million (PPM). If no color change occurs, then the
concentration of chloride salt ions within the collected sample is below the detectable level.
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Step Four: Calculate the concentration and record the results
Latex Sleeve Method
1 ppm = 1 µg/cm2
Swabbing or Bresle Patch Methods
{PPM x quantity of water used} ÷ area sampled
Most specifications will require the results of soluble salt testing to be expressed in terms of concentration,
not PPM. If the Latex Sleeve test was utilized to collect the sample, then no calculations are required as
manufacturers have already accounted for this. The volume of test solution within Chlor*Test Sleeve tests (in
milliliters) and the size of the test area (in square centimeters) within the Kitagawa titration tubes are designed
to cancel each other out. Therefore, the PPM value displayed on the titration tubes also equals the
concentration of chloride in µg/cm2. However, if the sample was collected using another method, then the
chloride concentration needs to be calculated. Instructions for these calculations can be found below in the
Calculating Concentrations section.
Finally, the results of the test should be recorded in the specified format, for example, 200 µg/cm2. If no
reading appears on the titration tube, then the results should be reported as “non-detectable, less than “X” of
chloride.” With “X” being the lowest value on the titration tube, typically 1 to 10 ppm (1 to 10 µg/cm2).
Calculating Concentrations
The concentration can be calculated based on:
1. The amount of water/solution used to collect the sample
2. The size of the area that was sampled
3. Formulas provided below
ƒ
{PPM x quantity of water used} ÷ area sampled
Below are two examples of how to convert from PPM to µg/cm2.
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Chapter 19: Soluble Salt Detection
Example using Sampling Method A (surface swabbing):
Entry
Result
PPM (lowest value on titrator tube)
<1 ppm chloride
Quantity of Water used (from Section 1)
5 ml of water
PPM x Quantity of Water Used
<1 x 5 = <5 micrograms of chloride
Area Tested (from Section 1)
103.2 = <0.05 micrograms/cm2 chloride
Micrograms of chloride ÷ Area Tested
5 ÷ 103.2 = <0.05 micrograms/cm2 chloride
Therefore, the lowest detection limit is 0.05 micrograms/cm2 (0.05 mg/cm2) when 5 ml of water is used and
103.2 cm2 of the surface is tested.
Example using Sampling Method C (Bresle PatchTM):
Entry
Result
PPM (lowest value on titrator tube)
<1 ppm chloride
Quantity of Water used (from Section 1)
2 ml of water
PPM x Quantity of Water Used
<1 x 2 = <2 micrograms of chloride
Area Tested (from Section 1)
12.25 cm2 of surface
Micrograms of chloride ÷ Area Tested
2 ÷ 12.25 = <0.16 micrograms/cm2 chloride
Therefore, the lowest detection limit is 0.16 micrograms/cm2 (0.16 mg/cm2) when 2 ml of water is used and
12.25 cm2 of surface is tested.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Rinse all equipment in clean distilled water to
prevent contamination.
ƒ
Never touch any parts of the tube with bare
hands that will come in direct contact with the
collected sample.
ƒ
Use the provided aspirator bulb to bring the
solution into the titration tube (if required).
–
If the sample does not begin to travel up the tube after 30 seconds.
ƒ
Snap both ends of the tube.
ƒ
Insert the tube into the sample the correct way up.
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Chapter 19: Soluble Salt Detection
Note that in many regions, these tubes are considered “sharps." Ensure that the tubes are discarded
according to relevant local regulations.
Calibration
Calibration is not required as titration tubes are a single-use item. Care should, however, be taken to select a
titration tube that measures the appropriate range. The tube most commonly used for surface testing of
chlorides has a detection range of +0 to 60 ppm. Other ranges include 3 to 200 ppm and 10 to 2000 ppm.
CSN Test Kits
A Chloride, Sulfate, and Nitrate Kit, commonly known
as a CSN Kit, is employed when the inspector is
required to measure the concentration of specific
salts. While on most coating projects, chlorides are
the focus when detecting and measuring soluble
salts, there will be select projects where the
inspector is required to measure sulfate or nitrate
concentrations. Water-soluble sulfates are
commonly produced by burning sulfur-containing oil
and coal in power plants, while nitrate contamination may come from fertilizers and may be present in rural
agricultural areas.
Sample Collection
CSN kits utilize the Latex Sleeve Method to collect a sample from the surface. The kits contain a pre-measured
bottle of Chlor*Test Solution that must be used with the sleeve to maintain the accuracy of subsequent tests.
The steps to collect a sample using the latex sleeves will commonly mirror the steps provided earlier in the
course. The inspector should, however, review the CSN kit’s instructions as there may be differences. One
point of difference is the addition of a filtering process. Once the sample has been collected, the inspector
should pour the solution into the auto-vial (filter) with the assistance of a disposable funnel. Next, the
inspector should return the solution back into the Chlor*Test Solution bottle by pushing down on the autovial’s plunger.
Sample Testing
Once the sample has been filtered and returned to the bottle, the CSN kit can be utilized to perform three
different tests. Each of these tests is designed to measure a specific salt.
ƒ
Chlorides
–
ƒ
To measure chloride concentration, a chloride titration tube is used, as described earlier in this
chapter.
Sulfates
–
To measure sulfate concentration:
1. Wipe the Chlor*Test solution bottle to remove any marks or fingerprints
2. Place the bottle inside the colorimeter and close the lid
–
16
When required, match the vertical line on the bottle with the line inside the colorimeter
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Chapter 19: Soluble Salt Detection
3. Turn the meter on and then hold the ‘zero’ button
–
Some meters will display 0.00 on the screen when zeroed; others might say BLA (Baseline
Adjustment).
4. Remove the bottle and add the barium chloride reagent
5. Place the lid back on the bottle and shake it for the specified time period
6. Wipe the bottle again and place it back inside the colorimeter with the lid closed
7. Press the red button
8. The concentration will be displayed on the screen in PPM
ƒ
Nitrates
–
To measure nitrate concentration:
1. Remove one nitrate ion test strip from the pack of five
2. Open the protective packaging at the marked end
3. Remove the strip taking care not to touch the test pad at the bottom
4. Dip the strip into the collected solution for 2 seconds (may vary)
5. Remove the strip and wait one minute while the color of the pad changes color
6. Match the color of the pad to the colors on the provided reference chart
7. Identify the reading that sits under the matching color; this is the nitrate concentration in PPM
Most CSN Kits contain pre-measured and pre-dosed materials to simplify the testing process. Results of the
tests are recorded in parts per million (ppm). These kits are also designed to use a ratio of 1:1 for easy
conversation of results to µg/cm² or microsiemens (μS), eliminating the need for complicated calculations.
Potassium Ferricyanide & Salt Meters
Salt contamination meters and potassium
ferricyanide paper are two methods that combine
both the collection and analysis process.
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Chapter 19: Soluble Salt Detection
Potassium Ferricyanide: Overview
The Potassium Ferricyanide test method is
employed to collect a sample from the substrate
and, at the same time, detect if soluble ferrous iron
salts are present. Unlike the other salts discussed in
this chapter, ferrous iron salts do not arise from the
external environment; they are formed during the
corrosion process. This test method is commonly
utilized to determine if soluble ferrous salts have
formed at the bottom of corrosion pits but can also
be used on other areas of the substrate.
The Potassium Ferricyanide test involves the application of special indication paper to a substrate that has
been misted with distilled water. The paper is then removed and examined. If ferrous soluble salts are
present, they will react with the potassium ferricyanide within the paper and form ferric hexacyanoferrate,
which turns the paper Prussian blue. This is a qualitative test as it is designed to simply determine if soluble
ferrous salts are or are not present; it is not designed to measure their concentration. On an informal level,
the amount of blue that appears on the paper can give some indication of the concentration of soluble salts.
Standards
The following standards describe the Potassium Ferricyanide test method
ƒ
SSPC Guide 15, Retrieval and Analysis of Soluble Salts
–
Method 5.8: Qualitative Field Detection of Ferrous Ion
Additional standards may be available for your region.
Method of Operation
The information below is a general description of
how to detect the presence of soluble ferrous salts
using the Potassium Ferricyanide method. Refer to
the project’s specification, referenced standard, and
manufacturer’s instructions for more specific
directions.
Step One: Identify the test site and verify that it is
properly prepared
Prior to performing the test, the inspector should then verify that the area is clean and dry. Any existing
moisture could mix with the deionized water sprayed during the procedure and contaminate it. Dust, dirt, and
residual abrasive will also stick to the indication paper and can adversely affect the results.
Step Two: Mist the surface of the test area
Pour either distilled or deionized water into a clean spray bottle, taking care to avoid contamination. Next,
spray a thin film/ fine mist of water onto the test area.
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Chapter 19: Soluble Salt Detection
Step Three: Apply the indication paper
Put on a clean pair of gloves and remove a piece of indication paper from the packet. When the water on the
surface has nearly evaporated, apply the paper to the surface. Hold the paper in place for 10 -15 seconds with
a thumb or forefinger to obtain good contact. During this time, any salts on the substrate should be drawn out
of the rust pits and surface profile by capillary action and onto the paper, where they will react with the
potassium ferricyanide.
Step Four: Examine the test paper and report the results
Gently remove the indication paper from the surface and then examine the underside. The presence of blue
spots or flecks on the paper indicates that soluble ferrous salts are present on that part of the substrate. The
results of the test should then be documented, preferably with a photo. On some projects, the inspector will
be required to keep the sample paper, which should be placed in a new, clean reusable bag.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Always keep the indicator paper in a clean and
dry location
ƒ
Use the indicator paper within 6 months
ƒ
Take a photo of the results as the paper will
deteriorate over time
ƒ
Always wear gloves and inspect the water for
signs of contamination
ƒ
Use the correct volume of water
–
Too little water and the soluble salts may not dissolve
–
Too much water and the Prussian Blue will spread across the paper
Important
Inspectors should always wash hands after handling Potassium Ferricyanide paper.
Calibration
Calibration is not required as potassium ferricyanide paper is a single-use item.
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Salt Contamination Meters: Overview
Salt contamination meters or soluble salt profilers
are employed to both collect a sample from the
substrate and to measure the concentration of the
soluble salts present. Unlike the potassium
ferricyanide test, this method can provide
quantitative results. When using a salt
contamination meter, water is added to the sample
paper, which is then held against the substrate using
a magnetic disc. After a specified duration, the
sample paper is removed and inserted into the meter. The meter then analyzes the concentration of the salts
and produces a reading; typically, in microsiemens per centimeter (μS/cm), milligrams per meter squared
(mg/m2), millisiemens per centimeter (mS/cm), micrograms per centimeter squared (μg/cm2) and parts per
million (ppm).
A distinct advantage of salt contamination meters is that readings can be obtained within two minutes versus
a recommended 10 minutes for obtaining the sample via the bresle patch, as recommended in ISO 8502-9 or
the latex sleeve method. Depending on the model and manufacturers, some salt contamination meters can
also provide date and time-stamped readings, break down a reading into quadrants, and generate salt density
maps.
Standards
The following standards describe the use of salt contamination meters:
ƒ
ISO 8502 Preparation of Steel Substrates Before Application of Paints and Related Products – Tests for the
Assessment of Surface Cleanliness
–
ƒ
Part 9: Field Method for the Conductometric Determination of Water-soluble Salts.
SSPC Guide 15, Retrieval and Analysis of Soluble Salts on Steel and Other Nonporous Substrates
–
4.1.1 Soluble Salt Meter
–
4.2.3 Saturated Special Filter Paper with Concentric Ring Conductivity Meter
Additional standards may be available for your region.
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Chapter 19: Soluble Salt Detection
Method of Operation
The information below is a general description of how to collect and analyze the sample using a salt
contamination meter. Refer to the project’s specification, any referenced standards, and manufacturer’s
instructions for more specific directions.
Step One: Identify the test site and verify that it is properly prepared
Identify the section(s) of the steel surface where the sample will be collected and verify that there is no loosely
adherent material present on the prepared surface. Any remaining material will adhere to the sample paper
and can adversely affect the analysis of the sample. Next, verify that the temperature is between 5° to 40°C
(41° to 104°F) and that the relative humidity is less than 80%. If the ambient conditions are outside this range,
readings may have to be adjusted to compensate. Note that some models of soluble salt meters automatically
compensate for ambient conditions.
Step Two: Prepare the salt contamination meter
Inspect the meter for signs of contamination, paying particular attention to the sensor area. If contaminants
like oil, grease, or dirt are visible, clean the sensor using the wipes provided by the manufacturer. Next,
power-up the meter by pressing the on/off button, which is typically located near the digital display. Then,
scroll through the menu options making any required changes. Common items to check are the language
settings, units of measurement, batch number, measurement mode, and paired devices.
Step Three: Prepare the sample paper
Put on a clean pair of disposable gloves and fill the provided syringe with 1.6 milliliters of distilled water.
Examine the magnetic disc (If provided) to ensure it is clean and dry. Then, using a pair of tweezers, remove a
piece of sample paper from the pack and place it on the non-labeled side of the magnetic disc. The paper can
also be held with the tweezers if a magnetic disc is not provided. Next, disperse the water from the syringe
evenly across the paper and wait for any bubbles to pop (if present).
Step Four: Apply the sample paper
Place the magnetic disc with the wetted paper face down onto the test area. Then firmly press the disc into
any contours or irregularities. If the inspector is working with a model of salt contamination meter that does
not contain a magnetic disc, then tweezers can be used to place the paper and gently push the paper into the
metal profile. Next, start a 2-minute timer on the meter, or if the meter does not have a timer, another
suitable device (be mindful of cross-contamination).
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Chapter 19: Soluble Salt Detection
Step Five: Remove and test the paper
After two minutes, use the tweezers to carefully remove the sample paper from the test surface and the
magnetic disc (if utilized). Then place the sample paper onto the sensor area of the soluble salt meter. Close
the lid and press the relevant button to begin the analysis. Note that some devices will automatically begin
measuring the sample as soon as the lid is closed. The reading will be displayed on screen in the chosen
measurement mode. Finally, record the results and repeat the process as specified. On some projects, the
inspector will be required to keep the sample paper. On these projects, the sample paper should be placed in
a new, clean reusable bag.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Avoid contamination of the sample by using
gloves and the tweezers
ƒ
Refer to the manufacturer’s user manual for the
operating parameters
ƒ
Verify that the environmental conditions are
within the equipment’s range
–
Pay particular attention to very high temperatures
Accuracy and Calibration
All conductivity meters should come with a Certificate of Calibration. Once in service, conductivity meters are
typically re-calibrated every 12 months by either the manufacturer or an authorized lab. Verification of
accuracy can also be performed by the inspector using the provided verification tiles, but this is not commonly
performed by a Level 1 inspector.
Specific Ion Detection
As discussed throughout this chapter, there are two
techniques for testing salt contamination. The
technique that you select is based on whether you
want to know both the quantity and type of salt that
is on the surface or whether you only want to know if
salts are present on the surface.
Most of the collection and testing methods
discussed in this chapter are used to detect if a
specific type of water-soluble salt is on the surface. Some manufacturers sell collection methods paired
together with certain testing/analysis methods in kits as they are frequently specified together within the
coatings industry.
Note that many collection methods are compatible with more than one type of testing/analysis method.
This chapter only focuses on the most frequently specified collection and testing/analysis methods.
However, there are additional methods beyond what is discussed in this chapter that are commercially
available, such as chloride and iron (ferrous ion) test strips. These test strips will not only indicate if a
particular type of salt is present on the surface but also the concentration of it as well.
22
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Chapter 19: Soluble Salt Detection
Conductivity
If you are testing only for conductivity, there are several collection methods to choose from, but only one
testing/analysis method that can be used, the conductivity meter. Keep in mind that conductivity testing will
not be able to tell you what type of salt is on the surface, only that there is some type of salt present that is
causing the electrical conductivity of the water to increase.
Important
Note that additional methods for collecting and analyzing soluble salts can be viewed in Table
One of SSPC Technology Guide 15 Field Methods for Extraction and Analysis of Soluble Salts on
Steel.
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CIP Level 1
Chapter 19: Soluble Salt Detection
Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. Which of the following procedures is used to test for ferrous salts?
A. Bresle Patch test
B. Sleeve Test
C. Potassium Ferricyanide Test
D. Salt Contamination Meter
2. When using titration tubes to analyze a sample taken from the surface, which color value
indicates the presence of chlorides in the test solution?
A. Pink
B. White
C. Blue
D. Yellow
3. According to ISO 8502-6, when collecting a test sample using the Bresle method, the water
should be re-injected into the cell a minimum of how many times?
A. Four times
B. Three times
C. Two times
D. Never, the water is only injected into the cell once
4. Which of the following methods is used to test for the presence of nitrates?
A. Salt Contamination Meter
B. Conductivity Meter
C. Titration Tubes
D. Ion Test Strips
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Chapter 19: Soluble Salt Detection
Self-Study Review
Answer the following questions for additional practice. To check your responses, refer to the
Answer Key in the Reference tab.
1. Types of Soluble Salt Contamination include:
2. If inspection is to be effective with regards to soluble salts, the specification should very
clearly state:
3. List the step to determine the relative humidity and dew point using the sling psychrometer:
25
Chapter 20: Measuring Surface Profile
Chapter 20:
Measuring Surface
Profile
20.1 Introduction
Learning Objectives
By the end of Chapter 20, students should be able to:
1. Accurately measure surface profile using comparators, digital profile gauges, and replica tape according to
ASTM D4417, Methods A, B, and C.
Surface Profile (Anchor Profile)
For protective coatings to perform as expected, they must be applied over a substrate that has been prepared
to a cleanliness standard and with specific profile or depth range. When abrasive media impacts the
substrate, the surface is converted from being relatively smooth to one full of “peaks” and “valleys” that, when
viewed under magnification, resemble a mountain range. The surface profile is the measurement of the
maximum peak-to-valley depth across a section of the substrate’s surface.
The standards that govern surface profile measurements prescribe how to measure surface profile depth but
do not provide an acceptance criterion. If the specification does not clearly define the requirements of the
surface profile, then the inspector must clarify them prior to taking any measurements. .
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Chapter 20: Measuring Surface Profile
Measuring Surface Profile
There are three main methods or instruments used in the field to measure surface profile.
1. Surface profile comparator
– Provides a visual and tactile comparison of steel substrates that have been blast-cleaned with either
shot abrasives or grit abrasives
2. Digital profile gauge
– Measures the peak-to-valley depth of the surface profile using a spring-loaded probe
3. Replica tape
– Generates an “impression (reverse image)“ of the surface profile that can then be measured with a
micrometer
On some projects, the inspector may be asked to perform a peak count in addition to measuring the surface
profile, but it is not yet common practice. A peak count is performed using a Portable Stylus instrument or a
digital micrometer with optical grade replica tape.
20.2 Surface Profile Comparators
Surface Comparators
Overview
A surface profile comparator is an instrument that
allows an inspector to estimate the surface profile of
a prepared surface. Comparators provide both a
visual and tactile comparison of steel substrates that
have been blast-cleaned with either shot abrasives
or grit abrasives. Comparators are designed to be
used with or without mangification of 5 to 10 power.
A Type G comparator is for surfaces prepared with
metallic or mineral grit, and Type S is for surfaces prepared with metallic shot. However, where appropriate,
these comparators can be used for assessing the roughness profile of blast-cleaned substrates prepared with
other types of abrasives.
Surface comparators typically contain four segments side-by-side, each with a different pattern or profile
depth. Further, the segments of most comparators are created to meet the requirements of ISO 8503-1.
ƒ
Type G Comparator segments 1 mil (25μm), 2.4 mils (60μm), 4 mils (100μm), 6 mils (150μm)
ƒ
Types S Comparator segments 1 mil (25μm), 1.6 mils (40μm), 2.8 mils (70μm), 4 mils (100μm)
Standards
The following standards describe the use of surface profile comparators.
ƒ
ASTM D4417, Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
–
2
Method A: Visual Surface Profile Comparator
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Chapter 20: Measuring Surface Profile
ƒ
ISO 8503, Preparation of steel substrates before application of paints and related products — Surface
roughness characteristics of blast-cleaned steel substrates
–
Part 1: Specifications and definitions for ISO surface profile comparators for the assessment of
abrasive blast-cleaned surfaces
–
Part 2: Method for the grading of surface profile of abrasive blast-cleaned steel — Comparator
procedure
–
Part 3: Method for the calibration of ISO surface profile comparators and for the determination of
surface profile — Focusing microscope procedure
–
Part 4: Method for the calibration of ISO surface profile comparators and for the determination of
surface profile — Stylus instrument procedure
Note that additional standards may be available for your region.
Method of Operation
The information below is a general description of how to measure the surface profile using a surface profile
comparator. Refer to the project’s specification, referenced standard, and manufacturer’s instructions for
more specific directions.
Step One: Verify that the test area is clean
Check that all loose dust, dirt, and debris is removed from the test surface; otherwise, it can alter its
appearance.
Step Two: Select the appropriate surface profile comparator
Type G should be used to assess surface profiles prepared by blast cleaning with metallic or mineral grit. Type
S should be used to assess surfaces prepared with metallic shot. On projects where other types of abrasives
were used, the type of comparator should be listed in the specification or first agreed upon by all the key
stakeholders.
Step Three: Compare the surface to the comparator
Hold the comparator against the area of the surface to be assessed. Then compare the roughness of the
prepared surface against the roughness of the four comparator segments. This can be done with the unaided
eye, under 5x to 10x illuminated magnification, or by touch. When using magnification, the magnifier should
be brought into intimate contact, so the depth range is sufficient for the comparator and surface to be in focus
simultaneously. Some magnifiers can be placed so that the test surface is viewed simultaneously with
different segments of the comparator.
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Chapter 20: Measuring Surface Profile
CIP Level 1
Step Four: Identify the comparable segment(s) and record the results
Select the comparator segment that most closely approximates the roughness of the surface being evaluated
or, if necessary, the two segments to which it is intermediate. Next, determine its grade using the table below.
It is important to highlight that while each comparator only has four quadrants, 5 grades are possible..
Comparator Grades
Finer-than-Fine
Any profile assessed as being lower than the limit for fine
Fine
Profiles equal to segment 1 and up to, but exluding segment 2
Medium
Profiles equal to segment 2 and up to, but excluding segment 3
Coarse
Profiles equal to segment 3 and up to, but excluding segment 4
Coarser-than-Coarse
Any profile assessed as being greater than the upper limit for coarse
Record the grades for all test areas of the surface as specified or agreed upon between the interested
stakeholders. The number of measurements required depends on the size and complexity of the surface
being measured. If any profile is assessed as being below the lower limit for the Fine grading, report the
grading as Finer-than-Fine. If any profile is assessed as being greater than the upper limit for the Course
grading, report the grading as being Coarser-than-Coarse.
If the surface falls between two segments, both segments should be recorded as range. Some specifications
may even specify a range for the acceptable profile, such as M/C (Medium or Course).
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Make sure that the grade (e.g., Fine, Medium,
etc.) is recorded and not the segment number
–
E.g., Recording “Segment 4” instead of
“Coarser-than-Coarse” would be invalid
Calibration
Worn or damaged surface profile comparators
should be replaced or discarded. Tarnished or discolored comparators can, however, often be cleaned by the
inspector. They can remove the tarnish without disturbing the electroformed pattern by rubbing the affected
area with a white plastic eraser. Other forms of erasers should not be used as these can leave an oily film,
making the staining worse.
4
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Chapter 20: Measuring Surface Profile
20.3 Digital Profile Gauge
Digital Profile Gauge
Overview
Digital profile gauges sometimes referred to as
depth micrometers or surface profile gauges, are
handheld instruments that measure the peak-tovalley depth of the surface profile using a springloaded pointed probe. When in use, the base of the
instrument rests on the peaks of the surface profile
while the spring-loaded pointed probe projects into
the valleys. When the probe reaches the bottom of
the valley, it calculates the valley’s depth relative to its peak and then displays the measurement on the
screen.
The exact capabilities of digital profile gauges vary between the models and manufacturers. While all models
will measure the peak to valley depth, some are also capable of recording:
ƒ
N - The number of readings taken
ƒ
X - The mean (average) of those readings
ƒ
O - The deviation (difference between a value in the frequency of the distribution and the mean) of those
multiple readings
ƒ
Hi - The highest (maximum) reading in those readings
ƒ
Lo - The lowest (minimum) reading in those readings
In addition, some models will walk the inspector through measuring the surface profile in accordance with
specific standards, such as ASTM D4417.
Standards
The following standards describe the use of digital profile gauges:
ƒ
ASTM D4417, Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
–
Method B: Surface Profile Depth Micrometer
ƒ
SSPC-PA 17, Procedure for Determining Conformance to Steel Profile/Surface Roughness/Peak Count
Requirements
ƒ
AS 3894.5-C, Site Testing of Protective Coatings Determination of Surface Profile
Note that additional standards may be available for your region.
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Chapter 20: Measuring Surface Profile
Method of Operation
The information below is a general description of how to measure the surface profile using a digital profile
gauge. Refer to the project’s specification, referenced standard, and manufacturer’s instructions for more
specific directions.
Step One: Prepare the gauge
Power up the digital profile gauge by holding the on/off button and waiting for 0.0 mil or 0.0 μm to appear on
the display. If an attachable probe is required (curved surfaces, tight spaces, etc.), it should be attached prior
to turning the gauge on. Next, access the set-up menu and check the settings. Common settings to check are
the units of measurement, measurement mode, and paired devices.
Important
Inspectors must pay close attention to the measurement mode they select. Some standards allow the
surface profile to be calculated using two different methods, which will produce different results. For
example, ASTM D4417 allows for either the “maximum” reading or the “average” reading of a spot to be
recorded.
Step Two: Zero the gauge
Locate the piece of float plate glass provided by the manufacturer and place it on a clean, horizontal surface.
Ensure the glass plate is clean, dust-free, not scratched, bent, or chipped prior to use. Next, select the “Zero”
option on the gauge. On some models, the option can be found by scrolling through the menu, and on other
models, there is a dedicated button. Next, hold the gauge by its base and press it firmly against the piece of
float plate glass at a 90° angle. Once the display reads 0.0 mil or 0 μm and the gauge is “zeroed” it is ready for
use. Note that if the float plate glass cannot be located, the “Factory Zero” setting can be used instead.
However, this option is not always precise.
Step Three: Perform 10 individual gauge readings at each location
Place the probe flat against the prepared surface. Hold the gauge steady until the gauge indicates that a
measurement has been obtained; the gauge will typically “Beep” and the profile depth will be displayed. If the
gauge does not store data, the inspector should record the measured profile depth before moving on to the
next measurement. Then, lift the probe from the surface and take the next reading. A total of 10 individual
gauge readings should be taken across a prescribed area. Discard any unusually high readings that cannot be
repeated in an area. Note that the group of 10 readings is referred to as a location. The recording of individual
gauge readings can be done by hand or by the statistical function of the gauge.
Note: Discard any unusually high readngs that cannot be repeated in an area.
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Chapter 20: Measuring Surface Profile
Both the number of measurement locations
required within a test area, and the size of the test
area itself can vary between projects. For the
purpose of this chapter, we will outline ASTM D4417:
Method B. When measuring in accordance with
ASTM D4417: Method B, the procedure is as follows.
First, the project’s stakeholders are required to agree
upon the number of “locations” that measurements
must be taken by the inspector. A “location” is a
cluster or group of 10 individual gauge readings.
Next, the stakeholders are required to agree upon both the size of the area that one “location” reading can be
taken across and the size of the wider test area. The inspector should have a clear understanding of these
requirements prior to beginning the measurement process.
Step Four: Perform the remaining spot readings, as specified
There are two steps to calculating surface profile, they are:
1. Determining the surface profile of each “location”.
2. Calculating the average surface profile of all the “locations.
ASTM D4417 allows for two different methods to be used in determining or calculating the surface profile
under Step 1.To elaborate, under Method 1, the inspector records the maximum reading out of the 10
individual gauge readings that were taken at a location as the profile height of the surface. Under Method 2,
the inspector does ten readings at each location and determines the average. For Step 2, once the surface
profile of each “location” has been determined, all the locations are averaged together to determine the
profile of the surface.
When ASTM D4417 is specified, the stakeholders need to agree on which method will be used to determine
the surface profile of a “location”. The two different methods will yield different results, as illustrated below.
Method 1: Record the maximum reading of a location (standard method)
or
Method 2: Record the average reading of a location (alternative method)
Surface Profile
Individual Gauge Readings - Location 1
2.1
Method 1
2.2
2.2
2.1
2.3
2.1
2.2
2.4
2.2
Method 1
Method 2
2.4 mils
2.2 mils
Location
Location
Location
Location
Location
Location
Location
Location
Location
Location
1
2
3
4
5
1
2
3
4
5
2.4
1.9
2.3
2.0
2.2
2.2
1.8
2.1
2.0
2.1
Surface Profile: 2.2 mils
Method 2
Surface Profile: 2 mils
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Chapter 20: Measuring Surface Profile
CIP Level 1
According to ASTM D4417, using Method 1 (maximum reading of each spot) has been shown to produce
results that correlate well with the replica tape and surface profile gauge methods. As a result, Method 1 is the
most popular in the field. It is important to note that when using Method 1, any unusually high gauge readings
that cannot be repeated in an area should be discarded; otherwise, the results will be skewed.
Verifying the Accuracy of the Gauge – ASTM D4417
On some projects, the digital profile gauge will be verified for
accuracy prior to use. Verification of accuracy may be performed if
the gauge does not zero (Step 2) or when measuring the profile in
accordance with select standards. For example, ASTM D4417
states that “Before use, each instrument’s accuracy shall be
verified by the user in accordance with the instructions of the
manufacturer, employing suitable standards and, if necessary,
any deficiencies found shall be corrected”. Either a metal shim or a
ceramic standard can be used to verify the accuracy of a digital
profile gauge.
To verify accuracy with a metal shim:
ƒ
Place the gauge, so the probe tip is centered on
the shim
–
ƒ
ƒ
To verify accuracy with a ceramic standard:
ƒ
The probe’s footprint should only contact
the left and right legs of the shim and not
the top of the cut-out
Verify that the display reads within the
combined tolerance of the shim (± 0.2 mil or
± 5 μm ) and gauge (± 0.2 mil or ± 5% which
ever is greater). For example, for a 76 μm shim
the average should be between 66-86 μm.
Place the gauge, so the probe tip passes
through the hole in the standard and rests on
the glass plate
–
The base of the gauge should rest on the
standard (but not on the label)
ƒ
Compare the gauge reading to the value
indicated on the ceramic standard
ƒ
Verify that the displayed reading is within 5% of
the standard reading
–
If it does not, do not try to adjust the gauge, the
gauge must be returned for service
ƒ
E.g., 19.68 mils (+/- 1 mil) or 500 μm (+/- 25
μm)
If it does not, do not try to adjust the gauge, the
tip must be replaced, or the gauge must be
returned for service
Note some gauges are having a hard reset function that will restore the gauge to the factory settings.
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Chapter 20: Measuring Surface Profile
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Remove interference material from the surface,
preventing the probe tip from being aligned flat
against the surface
ƒ
Zero the gauge before use
ƒ
Verify the requirements of the specified standard
–
E.g., some Australian standards require 30°
probes instead of 60°
ƒ
Take multiple readings as the surface measured is not uniform
ƒ
Avoid dragging the gauge across the surface between readings or banging the probe down hard on the
surface.
–
This can damage the spring-loaded tip, leading to false readings
ƒ
Avoid rocking the gauge on the surface while taking a measurement
ƒ
Discard any unusually high gauge readings that cannot be repeated in an area
–
Unusually high readings may occur due to dust or debris on the surface or warped surface
Calibration
Calibration is performed by the manufacturer or in a certified laboratory and is typically performed on an
annual basis. The calibration of the gauge can also be checked in the field by “zeroing” the gauge with a float
glass plate or by performing a verification of accuracy with the use of a metal shim or ceramic standard.
20.4 Replica Tape & Micrometer
Replica Tape
Overview
Replica tape allows an inspector to measure the
average peak-to-valley depth of the surface profile
by creating an “impression” of the profile. Replica
tape is comprised of two materials. The top side is
comprised of a non-compressible plastic film (Mylar),
and attached to the underside is a layer of
compressible foam. When the tape is impressed into
the blast cleaned surface using a burnishing tool, it
generates an “impression” of the surface profile. This impression is the mirror image of the surface profile and
can be measured to determine the peak-to-valley depth using a spring-loaded micrometer or a digital gauge.
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CIP Level 1
Chapter 20: Measuring Surface Profile
Replica tape comes in different grades (thicknesses) that accommodate different surface profile depths:
ƒ
Coarse Minus*: 0.5 to 1.0 mils (12 to 25 μm)
ƒ
Coarse: 0.8 to 2.5 mils (20 to 64 μm)
ƒ
Extra Coarse: 1.5 to 4.5 mils (38 to 115 μm)
ƒ
Extra Coarse Plus grade*: 4.6 to 5.0 mils (116 to 127 μm)
*These tape grades are typically restricted to checking measurements at the lower and upper-ends of the
Coarse or Extra Course ranges.
Standards
The following standards describe the use of replica
tape:
ƒ
ASTM D4417, Test Methods for Field
Measurement of Surface Profile of Blast Cleaned
Steel
–
Method C: Replica Tape
ƒ
NACE SP0287, Field Measurement of Surface
Profile of Abrasive Blast Cleaned Steel Surfaces
Using a Replica Tape
ƒ
ISO 8503, Preparation of steel substrates before application of paints and related products — Surface
roughness characteristics of blast-cleaned steel substrates
–
Part 5: Replica tape method for the determination of the surface profile
Note that additional standards may be available for your region.
Method of Operation
The information below is a general description of how to measure surface profile using replica tape and a
micrometer. Refer to the project’s specification, referenced standard, and manufacturer’s instructions for
more specific directions.
10
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Chapter 20: Measuring Surface Profile
Step One: Verify the test area is clean
Verify that there is no loosely adherent material present on the prepared surface, including dirt, dust, and
abrasive residue. Any remaining material will alter the impression taken and result in inaccurate readings. In
extreme conditions, surface temperature measurements may be required as replica tape should not be used
on surfaces outside the temperature range of –10 °C to 60 °C (14 °F to 140 °F). The compressible foam can
become too brittle under extreme cold or too pliable under extreme heat.
Step Two: Select the grade of replica tape
Select the appropriate grade of replica tape by comparing each tape’s grade to the project’s target surface
profile. The target profile should be listed within the specification and other key guidance documents. For
example, if the specification states that, “the surface profile shall measure between 1.0 and 2.2 mils (25 - 56
μm)”, the inspector would choose the Coarse grade of tape as it has a depth range of 0.8 to 2.5 mils (20 to 64
μm). This step is important as replica tape is most accurate when measuring surface profiles in the middle of
its depth range.
Step Three: Adjust the micrometer for the mylar thickness
As discussed earlier, the top section of replica tape is comprised of a non-compressible plastic film that is 2.0
mil (51 μm) thick. This depth needs to be accounted for either before the replica tape is measured or after the
replica tape is measured.
Manual Micrometer
To adjust the micrometer before the tape is measured, loosen the thumb screw and rotate the ring until the
needle is preset or “zeroed” to -2 mils (51 µm) to compensate for the mylar thickness. On a manual gauge, this
is equivalent to presetting to a plus 8.0 mils or on a metric gauge to plus 150 μm. This has the effect of presubtracting the depth of the incompressible film, and subsequent readings are a direct measure of the
profile’s depth. Alternatively, if the micrometer is adjusted to 0.0 when the contact surfaces are fully closed,
care must be taken to then subtract 51 μm (2.0 mil) from all subsequent readings.
ƒ
Digital Micrometer
The process to “zero” a digital spring micrometer will vary but typically involves selecting the ‘zero’ option
from the calibration menu and then checking that the digital display reads as “zero”. The inspector will
also need to input the grade of replica tape being used from the menu. It is important to note that some
manual and digital micrometers automatically subtract 2.0 mil (51 μm) from all readings, so reviewing the
manufacturer’s instructions is vital.
Important
When required, the accuracy of the micrometer can be verified with the use of a shim or
calibration foil.
Step Four: Attach and burnish the replica tape
Remove a piece of replica tape from the roll and carefully peel off the paper backing, exposing the adhesive.
Check that the protective circle or “bullseye” remains on the backing paper. Discard any tape that is damaged
or distorted.
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Chapter 20: Measuring Surface Profile
Step Five: Attach and burnish the replica tape
Attach the replica tape to the prepared surface, leaving one corner folded over to create a pull-tab. Burnish
the circular cut-out portion of the replica tape until it is uniformly darkened, and the impression assumes a
pebble-grain appearance. There should be no white streaks remaining. This burnishing process typically takes
30 to 40 seconds.
Step Six: Remove and measure the replica tape
Carefully lift the replica tape from the surface while taking care to avoid touching the adhesive side. Next,
place the tape between the anvils of the manual or digital micrometer.
ƒ
Manual Micrometer
Once the tape is in place, release the lever allowing the top and bottom anvils to close on the center of the
circular cut-out. Next, read the dial and record the results. Each division on the micrometer dial is 0.1 mil,
and each number represents mils. As an example, a reading of 5 means 5 mils (127 μm).
ƒ
Digital Micrometer
Ensure the tape is positioned so that the cut-out portion is centered under the opening of the probe. The
adhesive side should face down, and there are alignment dots on the tape that can help with its
placement. Once in position, press and hold the probe button until the device indicates the measurement
is complete (typically a beep or light flash). The measurement will then be displayed on-screen and should
be recorded.
Step Seven: Repeat the process with a second piece of tape
Most standards require that two replica tape samples are taken within a measurement area. If both readings
are in the 1.5 to 2.5 mil (38 to 64 μm) window, record the average of the two readings as the profile. However,
the second sample needs to be taken with a different grade of tape.
A different grade of tape is required when the surface profile of the first tape sample:
ƒ
Falls within the range of two different grades of tape
–
ƒ
For example, if a measurement with either Coarse or X-Coarse grade is in the 1.5 to 2.5 mil (38 to 64
μm) overlap window, take a second reading with the other grade
Sits at either end of the first grade’s depth range.
–
For example, if the readings obtained with either grade are outside the overlap window between
0.8 and 1.4 mils (20 to 37 μm) or between 2.6 and 4.5 mils (65 and 115 μm), it should be used as is.
Note that if the measured surface profile falls outside the range of the tape used, it is considered invalid.
The first measurement needs to be repeated or another grade of tape used.
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Chapter 20: Measuring Surface Profile
Important
On some projects, permission is required to use the minus and plus grades of replica tape.
Always refer to the manufacturer’s instructions and the project’s specification for guidance on
when to use the different grades of tape.
Step Eight: Calculate the surface profile
Calculate the surface profile by averaging the two readings obtained from the tape samples. For example, if
the first tape’s reading was 2.2 mils and the second tape’s reading was 2.3 mils, then the surface profile at this
location is 2.25 mils. Note that if the micrometer was not adjusted to account for the thickness of the mylar
during Step 3, then 2.0 mils/51 μm must also be subtracted from each of the individual tape readings.
Documenting Surface Profile Measurements – ASTM D4417
Select standards outline minimum reporting requirements for technical procedures. ASTM D4417 is one of
these standards. Section 11 of ASTM D4417 outlines both general reporting requirements and requirements
specific to each Method (A-D).
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Remove all interference materials from the
surface and micrometer anvils
ƒ
Burnish the mylar circle until it turns uniformly
gray, there are no visible white streaks, and has a
pebbled grain effect
ƒ
Fully compress all parts of the tape within the
micrometer
ƒ
Account for the thickness of the tape/mylar (2.0 mils/51 μm)
–
ƒ
Perform at least two measurements
–
ƒ
This can be achieved by adjusting the micrometer prior to performing the measurements or by
subtracting the thickness of the mylar from each reading
This helps to account for the inherent variation in point-to-point profile over the surface being
measured
Avoid use on surface profiles greater than 5.0 mils (127 μm)
–
When working with coatings that require a very deep surface profile (E.g., 100% solids polyurea
coating), specialized digital profile gauges should be use
13
CIP Level 1
Chapter 20: Measuring Surface Profile
Calibration
The micrometer should be verified for accuracy
routinely by inserting shims of known thickness into
the micrometer and verifying a correct
measurement. Plastic shims used to verify the
accuracy of coating thickness gauges can also be
used for this purpose. Like most digital instruments,
digital micrometers should be re-calibrated by the
manufacturer at least on an annual basis or as per
contractual specification.
20.5 Peak Density
Surface Roughness
On some/selected coating and lining projects, the
inspector may be required to measure surface
roughness. Peak density is the density of the peaks
in the roughness of the surface. It is the combined
measurements of the surface profile and the
frequency of peaks across a linear length (peak
count). An emerging body of research has shown
that the density of peaks across the surface, in
addition to the profile, are important contributors to
the adhesion of coatings, as both impacts the geometry of the surface. For example, the two cross-sections
below contain the same measured surface profile but possess very different geometries due to the density of
the peaks.
Surface Roughness: Importance
The importance of creating the correct surface roughness is evident when looking at coating projects
performed on the hulls of ships. The hull must be roughened to promote good coating adhesion. However, an
increase in underwater hull roughness can also result in a loss of speed and an increase in fuel consumption,
both of which can lead to a significant rise in vessel operating costs. As a result, a balance needs to be struck
between the hull containing sufficient roughness for coatings to adhere but also not being so rough that
significant drag is created when the vessel moves through the water.
14
© NACE International
Chapter 20: Measuring Surface Profile
Important
Surface roughness measurements are covered in greater detail within the Marine Coating
Inspection Course.
Standards
The following standards describe the use of portable stylus instruments or digital micrometers:
ƒ
ASTM D7127, Standard Test Method for Measurement of Surface Roughness of Abrasive Blast Cleaned
Metal Surfaces Using a Portable Stylus Instrument
ƒ
ASTM D4417, Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
–
Method D: Portable Stylus Surface Roughness Instrument
ƒ
ISO 4288, Surface texture: Profile method — Rules and procedures for the assessment of surface texture
ƒ
ISO 4287, Surface texture: Profile method — Terms, definitions and surface texture parameters
Measuring Peak Count
Surface roughness can be measured using a
portable stylus instrument or a digital micrometer.
Portable Stylus Instruments
Portable stylus instruments, otherwise known as
surface roughness testers, are the primary
instrument used to measure surface roughness.
They measure the roughness:
ƒ
With the use of a stylus that is mechanically drawn across the surface
ƒ
As the stylus moves across the surface, it records an image of the surface’s roughness
ƒ
This image is then utilized by the instrument to calculate the peak count and other parameters
Evaluation Length
Direction
of Travel
Stylus
Rmax
Rt
15
CIP Level 1
Chapter 20: Measuring Surface Profile
Digital Micrometers
Select digital micrometers can also measure surface roughness with the use of optical grade replica tape.
They measure the roughness:
ƒ
By shining a light through a piece of replica tape and then taking a photograph
–
ƒ
A 3D image of the surface can then be generated, and the peaks (light spots) counted
–
16
The back-lit photograph will display dark spots (valleys) and light spots (peaks)
Other measurement parameters can also be calculated, including roughness (Ra), peak density (Spd),
and peak to valley height (H).
© NACE International
Chapter 20: Measuring Surface Profile
Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. How should the surface profile be defined in a well-written specification?
A. As an exact measurement
B. Specifying only the maximum depth
C. Specifying only the minimum depth
D. As a range of measurements
2. You are on a project where Testex tape is specified to determine the surface profile by ASTM
D4417, Method C. Which of the following is likely to cause errors? (Select all that apply)
A. Dust on the surface
B. Using an incorrect grade of tape
C. Not accounting for the thickness of the mylar tape
D. Under burnishing the mylar tape
3. According to ASTM D4417 Method B, when taking measurements using a profile gauge at each
location you should ________________? (Select all that apply
A. Take 5 gauge readings in 3 locations, record the average value per location, then determine the average
of all locations as the reported profile
B. Take 3 gauge readings in 5 locations, record the average value per location, then determine the average
of all locations as the reported profile
C. Take10 readings per location, record the maximum value, then determine the average for all maximum
values as the reported profile
D. Take 10 readings and record the average of those ten (10) readings as the reported profile depth
17
CIP Level 1
Chapter 20: Measuring Surface Profile
Self-Study Review
Answer the following questions for additional practice. To check your responses, refer to the
Answer Key in the Reference tab.
1. Depth of surface profile can be evaluated by several methods, including:
2. The ISO Comparator grades may be recorded as:
3. The two types of replica tape that are commonly used are:
4. List the Standards for using the Replica tape:
5. When using Replica tape, common errors include:
18
© NACE International
Chapter 18: Measuring Environmental Conditions
Lab 1:
Measuring Environmental Conditions
Instructions
1. Measure the environmental conditions within the classroom using the following instruments:
ƒ
Magnetic Surface Temperature Gauge (Task 1)
ƒ
Sling Psychrometer with Psychrometric Tables (Task 1)
ƒ
Digital Dew Point Meter, using both the DeFelsko DPM and Elcometer 319 gauges (Task 2)
2. Document your results on the worksheets provided
3. Determine if the Delta T is at least 3°C (5°F)
Lab Worksheets
Note: Use metric or imperial units as appropriate.
Task 1: Analog Gauges
Project Name:
Date:
Time:
Measurement
Location:
Wet-Bulb
Temp:
Sling
Psychrometer:
Magnetic
Temperature Gauge:
 °C /  °F
Depression
(DB - WB):
 °C /  °F
 °C /  °F
Relative
Humidity:
%
Surface
Temp (Ts):
 °C /  °F
Delta T Value:
(Ts - Td = TΔ)
Is the Delta T ≥ 3°C/5°F?
Dry-Bulb
(air) Temp:
Dew Point
Temp (Td):
 °C /  °F
 °C /  °F
 Yes
 No
Comments or additional information:
1
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Task 2: Digital Gauges
Digital Dew
Point Meter:
Relative
Humidity:
%
Relative
Humidity:
%
Air Temp:
 °C /  °F
Air Temp:
 °C /  °F
Surface
Temp:
 °C /  °F
Surface
Temp:
 °C /  °F
Elcometer 319
Digital Dew
Point Meter:
Defelsko DPM
Dew Point
Temp:
 °C /  °F
Dew Point
Temp:
 °C /  °F
Delta T (TΔ):
(Ts - Td)
 °C /  °F
Delta T (TΔ):
(Ts - Td)
 °C /  °F
Is the Delta T ≥ 3°C/5°F?
 Yes
 No
Is the Delta T ≥ 3°C/5°F ?
 Yes
 No
Comments or additional information:
2
© NACE International
Chapter 18: Measuring Environmental Conditions
Dry
Bulb
Temp
51
Chart for Calculation of Relative Humidity and Dew Point
Depression of Wet-Bulb Temperature (°F)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
94/49 87/47 81/45 75/43 68/41 62/38 56/36 50/33 45/30 39/27 34/24 28/20 23/16
52
94/50 87/48 81/46 75/44 69/42 63/40 57/37 51/34 46/32 40/29 35/26 29/22 24/18 19/13
53
94/51 87/49 81/47 75/45 69/43 63/41 58/38 52/36 47/33 41/30 36/27 31/24 26/20 20/15
54
94/52 88/50 82/48 76/46 70/44 64/42 59/40 53/37 48/34 42/32 37/29 32/25 27/22 22/18
55
94/53 88/51 82/50 76/48 70/45 65/45 59/43 54/41 49/38 43/33 38/36 33/33 28/30 23/27 19/24
56
94/54 88/53 82/51 76/49 71/47 65/44 60/42 55/40 50/37 44/34 39/32 34/29 30/25 25/22 20/17
57
94/55 88/54 82/52 77/50 71/48 66/46 61/43 55/41 50/39 45/36 40/33 35/30 31/27 26/24 22/21
58
94/56 88/55 83/53 77/51 72/49 66/47 61/45 56/42 51/40 46/37 41/35 37/32 32/29 27/25 23/21
59
94/57 89/56 83/54 78/52 72/50 67/48 62/46 57/44 52/41 47/39 42/36 38/33 33/30 29/27 24/23 20/19
Reproduced by NACE with permission
60
94/58 89/57 83/55 78/53 73/51 68/49 63/47 58/45 53/43 48/40 43/38 39/35 34/32 30/29 26/25 21/21
61
94/59 89/58 84/56 78/54 73/52 68/50 63/48 58/46 54/44 49/42 44/39 40/36 35/33 31/30 27/27 22/23 18/19
62
94/60 89/59 84/57 79/55 74/53 69/51 64/48 59/47 54/45 50/43 45/43 41/40 36/38 32/35 38/32 24/29 20/25
63
95/61 90/60 84/58 79/56 74/55 69/53 64/51 60/49 55/47 50/44 46/42 42/39 37/36 33/34 29/30 25/27 21/23 17/19
64
95/62 90/61 84/59 79/57 74/56 70/54 65/52 60/50 56/48 51/46 47/43 43/41 38/38 34/35 30/32 26/29 22/25 18/21
65
95/63 90/62 85/60 80/59 75/57 70/55 66/53 61/51 56/49 52/47 48/45 44/42 39/40 35/37 31/34 27/31 24/27 20/24 16/19
66
95/64 90/63 85/61 80/60 75/58 71/56 66/54 61/52 57/50 53/48 48/46 44/44 40/41 36/38 31/35 29/32 25/29 21/26 17/22
67
95/65 90/64 85/62 80/61 75/59 71/57 66/55 62/53 58/52 53/49 49/47 45/45 41/43 37/40 33/37 30/34 26/31 22/28 19/24
68
95/67 90/65 85/63 80/62 76/60 71/58 67/57 62/55 58/53 54/51 50/49 46/46 42/44 38/42 34/39 31/36 27/33 23/29 20/26 16/22
69
95/68 90/66 85/64 81/63 76/61 72/59 67/58 63/56 59/54 55/52 51/50 47/48 43/45 39/43 35/40 32/37 28/34 24/31 21/28 18/24
70
95/69 90/67 86/65 81/64 77/62 72/61 68/58 64/57 59/55 55/53 51/51 48/49 44/47 40/44 36/42 33/39 29/36 25/33 22/30 19/26
71
95/70 90/68 86/67 81/65 77/63 72/62 68/60 64/58 60/56 56/54 52/52 48/50 45/48 41/46 37/43 33/41 30/38 27/35 23/31 20/28
72
95/71 91/69 86/68 82/66 77/64 73/63 69/61 65/59 61/58 57/56 53/54 49/52 45/50 42/47 38/45 34/42 31/40 28/37 24/33 21/30
73
95/72 91/70 86/69 82/67 78/66 73/64 69/62 65/60 61/59 57/57 53/55 50/53 46/51 42/49 39/46 35/44 32/41 29/38 25/35 22/32
74
95/73 91/71 86/70 82/68 78/67 74/65 69/63 65/62 61/60 58/58 54/56 50/54 47/52 43/50 39/48 36/45 33/43 29/40 26/37 23/34
75
96/74 91/72 86/71 82/69 78/68 74/66 70/64 66/63 62/61 58/59 54/57 51/55 47/54 44/51 40/49 37/47 34/44 30/42 27/39 24/36
76
96/75 91/73 87/72 82/70 78/69 74/67 70/66 66/64 62/62 59/60 55/59 51/57 48/55 44/53 41/51 38/48 34/46 31/43 28/41 25/38
77
96/76 91/74 87/73 83/71 79/70 74/68 71/67 67/65 63/63 59/62 56/60 52/58 48/56 45/54 42/52 39/50 35/48 32/45 29/42 26/39
78
96/77 91/75 87/74 83/72 79/71 75/69 71/68 67/66 63/64 60/63 56/61 53/59 49/57 46/55 43/53 39/51 36/49 33/46 30/44 27/41
79
96/78 91/76 87/75 83/73 79/72 75/70 71/69 68/67 64/66 60/64 57/62 53/60 50/59 46/57 43/55 40/53 37/50 34/48 31/46 28/43
80
96/79 91/77 87/76 83/74 79/73 75/72 72/70 68/68 64/67 61/65 57/63 54/62 50/60 47/58 44/56 41/54 38/52 35/50 32/47 29/44
81
96/80 91/78 87/77 83/75 79/74 75/73 72/71 68/70 64/68 61/66 57/65 54/63 50/61 47/59 44/57 41/55 38/53 35/51 32/49 29/46
82
96/81 91/79 87/78 83/77 80/75 76/74 72/72 69/71 65/69 61/67 58/66 55/64 51/62 48/60 45/59 42/57 39/55 36/52 33/50 30/48
83
96/82 92/80 88/79 84/78 80/76 76/75 72/73 69/72 65/70 62/69 58/67 55/65 51/64 48/62 45/60 42/58 39/56 37/54 34/52 31/49
84
96/83 92/81 88/80 84/79 80/77 76/76 73/74 69/73 65/71 62/70 59/68 56/66 52/65 49/63 46/61 43/59 40/57 37/55 35/53 32/51
85
96/84 92/82 88/81 84/80 80/78 76/77 73/75 70/74 66/72 62/71 59/69 56/68 52/66 49/64 46/62 43/61 41/59 38/57 35/54 32/52
86
96/85 92/83 88/82 84/81 81/79 77/78 73/76 70/75 66/73 63/72 60/70 57/69 53/67 50/65 47/64 44/62 42/60 39/58 36/56 33/54
87
96/86 92/84 88/83 85/82 81/80 77/79 73/78 70/76 66/75 63/73 60/72 57/70 53/68 50/67 47/65 45/63 42/61 39/59 36/57 34/57
88
96/87 92/85 88/84 85/83 81/81 77/80 74/79 70/77 67/76 64/74 61/73 57/71 54/69 51/68 48/66 46/64 43/62 40/61 37/59 35/57
89
96/88 92/86 88/85 85/84 81/82 77/81 74/80 71/78 67/77 64/75 61/74 58/72 54/71 51/69 48/67 46/66 43/64 40/62 38/60 36/58
90
96/89 92/87 89/86 85/85 81/83 78/82 74/81 71/79 68/78 65/76 61/75 58/73 55/72 52/70 49/69 47/67 44/65 41/63 39/61 36/59
91
96/90 92/88 89/87 85/86 81/85 78/83 75/82 71/80 68/79 65/78 62/76 59/75 55/73 52/71 49/70 47/68 44/66 41/65 40/63 36/61
92
96/91 92/89 89/88 85/87 82/86 78/84 75/83 72/81 68/80 65/79 62/77 59/76 56/74 53/73 50/71 48/69 45/68 42/66 40/64 37/62
93
96/92 93/90 89/89 85/88 82/87 78/85 75/84 72/83 68/81 66/80 62/78 60/77 56/75 53/74 50/72 48/71 45/69 43/67 40/65 37/63
94
96/93 93/92 89/90 85/89 82/88 79/86 75/85 72/84 69/82 66/81 63/79 60/78 57/76 54/75 51/74 49/72 46/70 43/68 41/67 38/65
95
96/95 93/94 89/92 85/91 82/90 79/88 75/87 72/86 69/84 66/83 63/82 60/80 57/79 54/77 51/76 49/73 46/71 43/70 42/68 38/66
96
96/95 93/94 89/92 86/91 82/90 79/88 76/87 73/86 69/84 66/83 63/82 61/80 58/79 55/77 52/76 50/74 47/72 44/71 42/69 39/67
97
96/96 93/95 89/93 86/92 82/91 79/89 76/88 73/87 69/85 67/84 64/83 61/81 58/80 55/78 52/77 50/75 47/74 44/72 43/70 39/69
98
96/97 93/96 89/94 86/93 83/92 79/90 76/89 73/88 70/87 67/85 64/84 61/82 58/81 56/79 53/78 50/76 48/75 45/73 43/72 40/70
99
96/98 89/97 89/95 86/94 83/93 80/92 76/90 73/89 70/88 67/86 64/85 62/83 59/82 56/81 53/79 51/78 48/76 45/74 44/73 41/71
100
96/99 89/98 89/96 86/95 83/94 80/93 77/91 73/90 70/89 68/87 65/86 62/85 59/83 56/82 54/80 51/79 49/77 46/76 44/74 41/72
Note: For any pair of figures, the first is relative humidity (%) and the second is dew point temperature (°F)
3
CIP Level 1
Dry
Bulb
Temp
(°C)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
Chapter 18: Measuring Environmental Conditions
Chart for Calculation of Relative Humidity and Dew Point
Depression of Wet-Bulb Temperature (°C)
(FOR USE IN NACE CLASSROOM ONLY)
Pressure – 1 Atmosphere
1
81/-3
83/-2
83/-1
84/-1
85/1
85/3
86/4
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87/6
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95/48
2
63/-6
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72/0
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3
45/-9
50/-8
51/-6
54/-5
56/-4
58/-3
59/-1
61/0
62/1
64/2
65/4
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84/46
4
28/-15
34/-13
36/-11
40/-9
42/-7
45/-6
46/-4
49/-3
51/-2
53/0
54/1
55/2
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79/44
1013 mb
1.013 bar
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20/-17
26/-15
27/-11
32/-10
35/-7
37/-7
39/-5
42/-3
43/-2
45/0
48/1
49/3
50/4
52/5
54/7
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52/12
61/13
61/15
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14/-19
19/-17
22/-13
26/-11
28/-9
31/-7
33/-5
36/-4
38/-2
40/0
41/1
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17/-14
21/-12
24/-9
26/-8
28/-5
31/-4
33/-2
35/0
37/1
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40/4
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13/-14
17/-13
19/-9
22/-8
25/-5
27/-4
29/-1
31/0
33/2
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14/-14
16/-10
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24/-4
26/-2
28/0
30/2
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12/-14
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25/-1
27/3
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30/6
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7/-17
10/-15
12/-10
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21/-1
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47/31
48/32
49/33
49/35
50/36
11/-10
13/-8
15/-5
18/-3
20/-1
21/1
23/3
24/5
26/7
28/9
29/10
30/12
32/13
33/15
34/16
35/17
36/19
37/20
38/21
39/23
40/24
41/25
42/26
42/27
43/28
43/29
44/31
45/32
46/33
46/34
8/-15
10/-10
12/-8
14/-5
16/-2
18/0
20/2
21/4
23/6
25/8
26/9
27/11
29/12
30/14
31/15
32/17
33/18
34/19
35/21
36/22
37/23
38/25
39/26
39/27
40/28
41/30
41/31
42/32
43/33
9/-14
9/-10
11/-7
13/-4
15/-1
17/1
19/3
20/5
22/7
23/8
25/10
26/12
27/13
28/15
29/16
30/18
31/19
32/20
33/22
34/23
35/24
36/26
37/27
37/28
38/29
39/30
39/32
9/-9
11/-6
12/-3
14/-1
16/1
18/4
19/6
21/7
22/9
23/11
24/13
26/14
27/16
28/17
29/19
30/20
31/21
32/23
32/24
33/25
34/26
35/28
36/29
36/30
15/2
17/4
18/6
20/8
21/10
22/12
23/13
24/15
25/17
27/18
28/19
28/21
29/22
30/23
31/25
32/26
33/27
33/29
13/1
14/3
16/5
17/7
18/9
20/11
21/13
22/14
23/16
24/18
25/19
26/20
27/22
28/23
29/24
30/26
30/27
14/4
15/6
17/8
18/10
19/12
20/14
21/15
22/17
23/18
24/20
25/21
26/23
27/24
27/25
NOTE: For any pair of numbers, the first number listed is the Relative Humidity and the second number is the Dew Point.
4
© NACE International
Chapter 18: Measuring Environmental Conditions
Extra Practice Worksheets
Task 1: Analog Gauges
Project Name:
Date:
Time:
Measurement
Location:
Wet-Bulb
Temp:
Sling
Psychrometer:
 °C /  °F
Dry-Bulb
(air) Temp:
 °C /  °F
Depression
(DB - WB):
Magnetic
Temperature Gauge:
 °C /  °F
Relative
Humidity:
%
Surface
Temp (Ts):
 °C /  °F
Dew Point
Temp (Td):
 °C /  °F
Delta T Value:
(Ts - Td = TΔ)
 °C /  °F
Is the Delta T ≥ 3°C/5°F?
 Yes
 No
Comments or additional information:
Task 2: Digital Gauges
Digital Dew
Point Meter:
Relative
Humidity:
%
Relative
Humidity:
%
Air Temp:
 °C /  °F
Air Temp:
 °C /  °F
Surface
Temp:
 °C /  °F
Surface
Temp:
 °C /  °F
Elcometer 319
Digital Dew
Point Meter:
Defelsko DPM
Dew Point
Temp:
 °C /  °F
Dew Point
Temp:
 °C /  °F
Delta T (TΔ):
(Ts - Td)
 °C /  °F
Delta T (TΔ):
(Ts - Td)
 °C /  °F
Is the Delta T ≥ 3°C/5°F?
 Yes
 No
Is the Delta T ≥ 3°C/5°F?
 Yes
 No
Comments or additional information:
5
CIP Level 1
6
Chapter 18: Measuring Environmental Conditions
© NACE International
Chapter 18: Measuring Environmental Conditions
Lab 2:
Testing for Soluble Salts
Instructions
Task 1 - Observe the instructor’s demonstration of:
1. Collecting a sample from the surface using one of the following methods:
ƒ
Bresle Patch (Latex Cell)
ƒ
Latex Sleeve
2. Testing the collected sample using one of the following methods:
ƒ
Titration Tube
ƒ
Conductivity Meter (DeFelsko PosiTector SST)
Task 2 - Perform a soluble salts test using the DeFelsko PosiTector SST with the PosiPatch:
1. Prepare the practice panel by sprinkling a pinch of salt on the surface of the panel
2. Add a couple of drops of deionized (DI) water to the salt and rub the salt into the surface
3. Test the practice panel for the presence and quantity of chlorides
4. Document your results on the worksheet provided
5. After each test, rinse the test cell of the meter with deionized water several times, shaking the water out
after each use
Note: To prevent contamination, never reinsert the used needle (from collecting the sample from the surface)
back into the deionized water.
Instructions for testing for soluble salts using the DeFelsko PosiTector SST with the PosiPatch:
 Turn on the PosiTector SST by pressing the
button
 Obtain a background conductivity measurement (Y1)
ƒ
Pour 4 ml (milliliters) of deionized water into the cup to prevent contamination of the water source
ƒ
Fill the syringe with slightly more than 3 ml of the deionized water
ƒ
Completely fill the meter’s test cell with water (approximately 1 ml)
ƒ
Wait for the meter to stabilize and click the ‘+’ button
ƒ
Draw the solution back into the syringe
ƒ
With the syringe pointing up, expel any excess solution and air until there is 3.0 ml of deionized water
 Prepare and attach the PosiPatch
ƒ
Turn the patch and magnetic ring upside down
ƒ
Place the reusable patch into the magnetic ring, ensuring the arrows align with the injection port
–
ƒ
Do not touch the patch’s interior to prevent contamination
Carefully place the magnetic ring on the test area
1
CIP Level 1
Chapter 18: Measuring Environmental Conditions
 Collect the sample
ƒ
Slowly inject 3.0 ml of DI water in the port using the plastic dispensing tip. When using on horizontal
surfaces, fully insert the dispensing tip into the PosiPatch. On vertical surfaces, insert the dispensing
tip only as far as is needed to see the tip inside the PosiPatch
ƒ
Press the ‘+’ button to start the 2-minute test timer
ƒ
Without removing the needle, withdrawal and inject the water four times
ƒ
After the 2-minutes, withdraw all of the water from the patch
 Test the collected sample
ƒ
Fill the meter’s test cell with the collected sample
ƒ
Wait for the reading to stabilize (up to 5 seconds)
ƒ
Press the ‘+’ button to save the results
Lab Worksheets
Note: Use metric or imperial units as appropriate.
Task 1: Instructor Demonstration and/or Student Practice
Test Method: Bresle Patch and Conductivity Meter
Method 1 - Drop Sample
Method 2 - Immersion
Conductivity
(µS/cm or mS/cm)
Instrument Model and Manufacturer:
Volume of extraction liquid used:
Test Method: Latex Sleeve and Titration Tube
Document your test results in micrograms per square centimeter and parts per million.
Test Results:
µS/cm or mS/cm
ppm
Instrument Model and Manufacturer:
2
© NACE International
Chapter 18: Measuring Environmental Conditions
Task 2: Student Practice
Test Method: DeFelsko PosiTector SST with PosiPatch
T2 = Temperature
Δy = Conductivity
ρA =Salt Density
t = Test Duration
Panel Side 1
Panel Side 2
(optional)
3
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Extra Practice Worksheets
Task 1: Instructor Demonstration and/or Student Practice
Test Method: Bresle Patch and Conductivity Meter
Method 1 - Drop Sample
Method 2 - Immersion
Conductivity
(µS/cm or mS/cm)
Instrument Model and Manufacturer:
Volume of extraction liquid used:
Test Method: Latex Sleeve and Titration Tube
Document your test results in micrograms per square centimeter and parts per million.
Test Results:
µS/cm or mS/cm
ppm
Instrument Model and Manufacturer:
Task 2: Student Practice
Test Method: PosiTector SST with PosiPatch
T2 = Temperature
Δy = Conductivity
ρA =Salt Density
t = Test Duration
Panel Side 1
Panel Side 2
(optional)
4
© NACE International
Chapter 18: Measuring Environmental Conditions
Lab 3:
Measuring Surface Profile
Instructions
1. Measure the surface profile of both sides of the prepared practice panel using:
ƒ
Surface profile comparators (Task 1)
ƒ
Digital profile gauges, both Elcometer 224 and DeFelsko PosiTector SPG (Task 2)
ƒ
Replica tape, using both the Testex manual micrometer and digital DeFelsko PosiTector RTR (Task 3)
2. Document your results on the worksheets provided
Lab Worksheets
Note: Use metric or imperial units as appropriate.
Task 1: Surface Profile Comparator
Use the ISO comparators (grit or shot) to check the profile of the practice panel provided. Document the
results in the table below using the proper grade.
Instrument Manufacturer:
Type of Comparator Used (G or S)
Grade
Panel Side 1
Panel Side 2
1
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Task 2: Digital Profile Gauge
Measure the surface profile of the practice panel provided using both the DeFelsko PosiTector SPG and the
Elcometer 224 gauges. Separate tables are included for each gauge. Take 10 measurements on each side of
the panel and record the maximum reading of each location. Then calculate the average surface profile of all
the locations. Document the results in the table below.
Before taking any measurements, zero the gauge using the glass plate provided.
Instrument Model and Manufacturer: Elcometer 224
Record Individual Gauge Readings (optional):
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
R8
R9
R10
Location A
(Panel
Side 1)
Location B
(Panel
Side 2)
Location A
Panel Side 1 Max:
Location B
Panel Side 2 Max:
Surface Profile (average):
 mils /  µm
Instrument Model and Manufacturer: DeFelsko PosiTector SPG
Record Individual Gauge Readings (optional):
R1
R2
R3
R4
R5
R6
R7
Location A
(Panel
Side 1)
Location B
(Panel
Side 2)
Location A
Panel Side 1 Max:
Surface Profile (average):
2
Location B
Panel Side 2 Max:
 mils /  µm
© NACE International
Chapter 18: Measuring Environmental Conditions
Task 3: Replica Tape
Measure the surface profile on both sides of the practice panel provided using both the DeFelsko PosiTector
RTR and the manual Testex Micrometer. Separate tables are included for each gauge. Take two readings on
each side of the test panel and average. Document the results in the table below.
Micrometer Model and Manufacturer: Testex Micrometer (manual gauge)
Tape Type
Reading 1
Reading 2
Average
Panel Side 1
 mils /  µm
Panel Side 2
 mils /  µm
Attach Replica Tape(s) in the spaces below
Replica Tape #2
Replica Tape #1
Panel Side 1
Panel Side 2
Micrometer Model and Manufacturer: DeFelsko PosiTector RTR (digital gauge)
Tape Type
Reading 1
Reading 2
Average
Panel Side 1
 mils /  µm
Panel Side 2
 mils /  µm
Attach Replica Tape(s) in the spaces below
Replica Tape #1
Replica Tape #2
Panel Side 1
Panel Side 2
3
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Extra Practice Worksheets
Surface Profile Comparator
Instrument Manufacturer:
Type of Comparator Used (G or S)
Grade
Panel 1
Panel 2
Digital Surface Profile Gauge
Instrument Model and Manufacturer:
Record Individual Gauge Readings (optional):
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
Location
A (Panel
Side 1)
Location
B (Panel
Side 2)
Location A
Panel Side 1 Max:
Surface Profile (average):
4
Location B
Panel Side 2 Max:
 mils /  µm
© NACE International
Chapter 18: Measuring Environmental Conditions
Replica Tape
Micrometer Model and Manufacturer:
Tape Type
Reading 1
Reading 2
Average
Panel Side 1
 mils /  µm
Panel Side 2
 mils /  µm
Attach Replica Tape(s) in the spaces below
Replica Tape #1
Replica Tape #2
Panel Side 1
Panel Side 2
5
Chapter 21: Measuring Film Thickness
Chapter 21:
Measuring Film
Thickness
21.1 Introduction
Learning Objectives
By the end of Chapter 21, students should be able to:
1. Explain how to measure the wet film thickness (WFT) of an applied coating using a comb or wet film
thickness gauge.
2. Accurately measure the dry film thickness (DFT) of an applied coating using Type I and Type II DFT gauges.
3. Accurately measure the dry film thickness of an applied coating in accordance with SSPC-PA 2 and ISO
19840.
Review: Film Thickness
Film thickness refers to the depth or thickness of the
applied coating material. A well-written coating
specification will provide a minimum and maximum
coating thickness for each layer of coating and for
the entire coating system. Correct thickness plays a
vital role in ensuring optimum coating performance.
Film thickness can be measured at both the wet film
and dry film stage.
Wet film thickness (WFT) refers to the thickness of the coating immediately after application and prior to any
curing or solvent evaporation. Dry film thickness (DFT) refers to the thickness of a coating system once all
solvents have evaporated and the coating has cured. Wet film thickness gauges are primarily used by
craftworkers during the application process whereas dry film thickness gauges are typically used by
inspectors.
1
CIP Level 1
Chapter 21: Measuring Film Thickness
Test Methods
Performing film thickness measurements is arguably
the single most important measurement performed
by an inspector during the application of protective
coatings. Non-destructive film thickness instruments
can be broken down into two categories: wet and dry
gauges.
On nearly all coating projects, the inspector will be
required to measure the film thickness of applied
coatings. It is one of the most important measurements throughout the entire coating installation process.
The methods, and corresponding equipment, employed by inspectors to measure film thickness can be
broken down into two categories. Wet film instruments and dry film instruments. Dry film instruments can be
further broken down into Type I gauges, which are analog, and Type II gauges, which are digital.
21.2 Wet Film Thickness
Comb Gauge: Overview
A comb, also referred to as a notch gauge, is a tool
that allows the applicator or inspector to measure
the wet film thickness (WFT) of a single layer of
coating. Comb gauges contain a series of precisely
measured notches or “teeth” along their side. When
the gauge is pressed into the wet film of a coating,
some of the notches will be coated, and others will
not. By examining which notches are and are not
coated, the inspector can identify the approximate
WFT of the coating material. Comb gauges come in a variety of shapes and contain different measurement
ranges based on the number of notches on each comb and the height interval between those notches.
Inspectors should select the comb gauge based on the requirements of each project.
WFT measurements are commonly performed by applicators, not inspectors. There are, however, two main
instances where inspectors perform WFT measurements.
1. To verify if the coating application process is on track to reach the specified DFT.
2. To verify the film thickness when the DFT cannot be measured after drying/curing.
Standards
The following standards describe the use of a comb gauge.
ƒ
ASTM D4414 Standard Practice for Measurement of Wet Film Thickness by Notch Gages
ƒ
ISO 2808 Paints and varnishes - Determination of film thickness
ƒ
AS/NZS 1580.107.3 Methods of test for paints and related materials - Determination of wet film thickness
by gauge
Additional standards may be available for your region.
2
© NACE International
Chapter 21: Measuring Film Thickness
Method of Operation
The information below is a general description of
how to measure the wet film thickness of an applied
coating using a comb gauge. Refer to the project’s
specification, referenced standard, and
manufacturer’s instructions for more specific
directions.
Step One: Select the appropriate comb gauge and
edge
Select a comb gauge based on the target WFT range for the coating material. Different gauges measure
different wet film thickness ranges, and then each side of the gauge will typically break down the range even
further. The range of the gauge can be identified by reading the measurements next to each notch. Most
gauges have imperial units on one side and metric on the other, but some gauges contain only one unit of
measurement.
Step Two: Inspect the comb gauge
Verify that the comb gauge is clean, dry, and undamaged. When the gauge is pressed into the wet coating film,
any contaminants or moisture on the gauge may remain within the film or be pushed into the underlying
substrate. The inspector should also examine the notches of the comb for any signs of damage or distortion.
If any notches are dented, chipped, or bent, they will produce incorrect readings, so the gauge should not be
used.
Step Three: Measure the WFT and record the results
Hold the comb gauge perpendicular to the wet coating film (90° angle) and then press the gauge firmly into
the film. The outermost notches of the gauge should touch the substrate or previous layer of coating. Next,
remove the comb from the wet film and examine the notches of the comb. Identify which notches have
coating on them and which do not. Note that if all of the teeth are coated, the inspector needs to use a gauge/
edge with a higher thickness range, and if none are coated, a lower thickness range is required. The true WFT
may lie between the highest numbered notch with coating on it and the next higher notch that is clean.
However, when recording the WFT measurement on most projects, the highest notch that is coated should be
recorded.
Important
If the specification lists a specific standard for WFT measurements, there can be variations in
how the value is recorded. Some specifications will require the inspector to average the value of
the highest numbered notch with coating on it and the value of the next higher notch that is
clean. The average will then be recorded as the WFT.
Step Four: Clean the gauge and repeat the process
Clean the comb gauge after each measurement using a suitable, mild solvent or a clean cloth. After cleaning,
ensure that all coating material has been removed and that the gauge is dry. Next, continue to take
measurements until the specified amount and locations have been measured.
3
CIP Level 1
Chapter 21: Measuring Film Thickness
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Measure the WFT as soon as possible after the
coating has been applied
ƒ
Avoid dragging the gauge through wet coating
(this causes a false high reading)
ƒ
Wipe the gauge clean between each
measurement to avoid coating build-up
ƒ
Inspect the notches/teeth of the gauge for damage
ƒ
Take care to place the gauge along the longitudinal axis when measuring WFT on pipes or curved surfaces
Important
The longer the wait between application and measurement, the less accurate the results
become. This is due to the drying and curing process beginning as soon as the coating is applied.
For example, when a coating is applied that cures through solvent evaporation, the solvent will
begin escaping from the film. This evaporation of solvent will reduce the thicknesses of the wet
coating film.
Calibration & Accuracy
Worn, bent, or damaged WFT combs should be replaced. It is important to note that comb gauges only
provide an approximate measure of WFT. In addition, attempts to measure the WFT of quick-dry coatings,
inorganic zinc-rich primers, powder coatings, and thermal spray coatings will often generate inaccurate
results.
21.3 Type I DFT Gauges
Type I (Analog) DFT Gauge: Overview
Type I DFT Gauges are magnetic instruments that
enable the inspector to measure the DFT of a single
layer of coating film or multiple layers combined.
Type I gauges are commonly referred to as magnetic
pull-off gauges as they produce a static magnetic
field when a permanent magnet is brought into
direct contact with the coated surface. The gauge
then measures the force required to overcome the
magnetic attraction between a magnet and a
magnetic substrate. In other words, they measure the force required to pull the magnet off the surface, this
force is converted to coating thickness value, and the value is displayed on an analog dial (scale) on the gauge.
The more force that is required, the thinner the coating layer is.
4
© NACE International
Chapter 21: Measuring Film Thickness
Magnetic pull-off gauges are inexpensive, portable and can also be used in areas where electronic gauges
(Type II DFT gauges) may cause problems. As an example, they are commonly used within flammable
atmospheres as Type I gauges are considered “non-sparking” and intrinsically safe. Some Type I gauges can
also be used underwater.
There are two different types of Type I gauges; dial type and pencil type.
Dial type gauges, commonly referred to as “Banana Gauges” or a
“Mechanical Gauges,” are widely used. Whereas pencil type gauges are
used for specialized applications such as very small or hard-to-reach areas
(bolt heads, rebar, small diameter piping, edges, etc.). Some pencil type
gauges can only be used either vertically or horizontally, while others can
be used in either orientation.
Keep in mind that when using Type I gauges, different models measure
different film thickness ranges. It is important that the inspector verify
that the model of their Type I gauge can measure the target DFT of the
coating material as per the specification or the coating’s product data
sheet.
Model A
0 - 8 mils
0 - 203 µm
Model B
0 - 40 mils
0 - 1016 µm
Model C
0 - 80 mils
0 - 2032 µm
Model D
25 - 250 mils
635 - 6350 µm
Standards
The following standards describe the use of Type I DFT Gauges:
ƒ
SSPC-PA 2 Paint Application Standard No. 2
–
Procedure for Determining Conformance to Dry Coating Thickness Requirements
ƒ
ASTM D7091 Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic
Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous
Metals
ƒ
ISO 19840 Paints and varnishes — Corrosion protection of steel structures by protective paint systems
–
Measurement of, and acceptance criteria for, the thickness of dry films on rough surfaces
Method of Operation
The information below is a general description of
how to perform a single DFT measurement using a
Type I gauge. Determining if a recorded
measurement is in conformance with the
specification is a more complex process that will be
discussed later in this chapter.
Dial Type Gauge
1. Place the gauge on the coated test surface.
2. Rotate the dial forwards (counterclockwise) using your finger or thumb beyond the expected thickness and
press the button to hold the magnet against the surface.
3. Slowly and steadily rotate the dial backward (clockwise), increasing the spring tension until the magnet
breaks contact with the surface.
5
CIP Level 1
Chapter 21: Measuring Film Thickness
4. Some gauges contain a counterweight button on the underside that, when released, will automatically
rotate the dial and stop when the magnet releases.
5. Identify the number on the dial that lines up with the vertical hairline or arrow on the dial’s cover.
6. Record this number as the unadjusted coating thickness at this test location.
Important
To avoid inaccurate readings, the inspector must stop turning the dial as soon as the magnet
breaks contact. In addition to hearing the magnet release, most gauges also have an indicator of
some fashion that will pop up, so close attention should be paid.
Pencil Type Gauge
1. Place the tip of the pencil on the coated surface and allow the magnet to contact.
2. Slowly pull the pencil perpendicularly from the substrate while keeping a close watch on the appropriate
indicator.
3. Identify the number on the indicator that lines up with the line.
4. Record this number as the unadjusted coating thickness at this test location.
Important
Some pencil type gauges will have one indicator, whereas others will have different indicators
depending on the position of the pencil. As an example, a red line when measurements are
performed horizontally, a green line when performed pointing vertically down, and a blue line
when pointing vertically up. Some pencil gauges can only be used in either a horizontal or
vertical position.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Verify the gauge for accuracy at the beginning of
each work shift or as specified
ƒ
Measure each layer before the next one is
applied
–
Type I gauges can only measure the distance
between the gauge and substrate; they
cannot differentiate between layers
ƒ
Verify the magnet is free from magnetic particles (steel grit, iron filings, swarf, etc.) and other interference
materials
ƒ
Cease turning the dial when the magnet releases
ƒ
Rotate the dial at a steady pace when taking measurements
6
© NACE International
Chapter 21: Measuring Film Thickness
ƒ
Account for the impact of the surface profile by subtracting the BMR or Correction Value from readings
–
This will be discussed in the standards section
ƒ
Position the gauge along the longitudinal axis of a pipe or curved surface
ƒ
Do not use:
–
Within 2.5 cm (1 in.) of an edge, as the physical properties of the metal’s edge change, and this affects
its magnetism
–
On or near vibrating equipment as the vibrations may prematurely lift the gauge
–
On metal being welded as the unit may become demagnetized
–
On tacky or soft surfaces as they may prevent the magnet from lifting properly and can contaminate it
21.4 Type II DFT Gauges
Type II (Digital) DFT Gauge: Overview
Type II gauges are commonly referred to as
electronic or digital gauges and are relatively easy to
use. Type II instruments use an electronic probe to
generate a magnetic field (Hall-effect, magnetic
induction, or eddy current) to measure the gap
(distance) between the substrate and the probe. This
measured distance is then converted into coating
thickness reading.
In addition to ease of use, Type II gauges are popular as they can perform DFT measurements faster than Type
I gauges. They are also less susceptible to vibrations than Type I gauges and select models can measure film
thickness on non-magnetic surfaces such as aluminum and most types of stainless steel. Keep in mind that
when selecting a Type II gauge that different models measure different film thickness ranges. For example,
some models may only measure film thickness up to 60 mils (1,500 μm), while other models may only
measure film thickness up to 1,220 mils (31,000 μm) on ferrous metal substrates.
Many Type II gauges can store readings in batches or groups. This capability allows users to take readings in
multiple areas, view the results at once, and then keep the data stored for future use. Many manufacturers
have also created gauges with software synchronizing capabilities that enable data to be transferred to other
devices through USB, Bluetooth, or WiFi. This can be particularly useful when a coating project requires digital
record keeping or if the data needs to be mapped, graphed, or analyzed.
7
CIP Level 1
Chapter 21: Measuring Film Thickness
Standards
The following standards describe the use of Type II DFT Gauges:
ƒ
SSPC-PA 2 Paint Application Standard No. 2
–
Procedure for Determining Conformance to Dry Coating Thickness Requirements
ƒ
ASTM D7091 Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic
Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous
Metals
ƒ
ISO 19840 Paints and varnishes — Corrosion protection of steel structures by protective paint systems
–
ƒ
Measurement of, and acceptance criteria for, the thickness of dry films on rough surfaces
AS 3894.3 Site testing of protective coatings
–
Determination of dry film thickness
Additional standards may also be available for your region.
Method of Operation
The information below is a general description of
how to perform a single DFT measurement using a
Type II gauge. Determining if a recorded
measurement is in conformance with the
specification is a more complex process that will be
discussed later in this chapter as will verifying the
accuracy of the gauge.
1. Turn the gauge on by pressing the center
navigation button.
2. Place the probe flat against the coated surface at a 90-degree angle.
ƒ
Some gauges may require the inspector to push down gently or press a button to take the
measurement.
3. Hold the gauge steady until the gauge indicates that a measurement has been taken.
ƒ
When a valid measurement is obtained, the gauge will typically “beep,” or a light will flash, and then the
DFT reading will be displayed.
4. Record the gauge reading (if the gauge does not store data).
5. Lift the gauge above the surface and place it on the next test site.
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Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
ƒ
Place the fixed, integrated probe perpendicular
to the substrate when performing
measurements
–
Separate, cabled probes are available in
various shapes and sizes to ensure
perpendicular placement
–
Probe must remain in contact with the
coated surface
Avoid dragging or rocking the probe as this can cause damage
–
ƒ
ƒ
Note that specialized scan probes can be dragged
Use interchangeable probes for:
–
Hard-to-reach areas
–
Curved surface
–
Challenging environments (underwater, high-temperature, etc.)
Always read the user manual for your specific model
–
Each gauge’s capabilities and functionality will vary greatly
ƒ
Perform the required firmware and software updates
ƒ
Make appropriate adjustments for the surface profile
–
ƒ
This process will be discussed in detail later in this chapter
Do not perform measurements on dirty, tacky, or soft films
–
The pressure on the probe can indent the coating yielding false low measurements, or coating
materials may contaminate the probe yielding false high measurements.
ƒ
Always check the batteries before use
ƒ
Account for the edge effect as defined by ASTM B244; the gauge is sensitive to abrupt changes in surface
contour
ƒ
–
Modern gauges can measure accurately right up to the edge as long as the probe does not hang over
the edge itself.
–
Probes should be calibrated to the edge being measured
Verify that the shims are in good condition before they are used to ensure the accuracy of the gauge. Foils/
shims will wear more quickly when used on roughened surfaces.
–
This process will be discussed in detail later in this chapter
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21.5 The DFT Inspection Process
Standards
DFT measurements are commonly performed
according to two different industry standards,
SSPC-PA 2 and ISO 8501. It is important to note that
the measurement process for each standard is
different. The specific process for each standard will
be covered later in this chapter.
Although SSPC-PA 2 and ISO 19840 will be the focus
of this chapter, it is important to highlight that select
countries and industries may have their own standards that govern the measurement of DFT. For example,
Australian Standard AS 3894 or ASTM D7091, which is referenced within SSPC-PA 2.
ƒ
SSPC PA-2: Procedure for Determining Conformance to Dry Coating Thickness Requirements
ƒ
ISO 19840: Measurement of, and Acceptance Criteria for, the Thickness of Dry Films on Rough Surfaces
ƒ
Australian Standard AS 3894.3: Site Testing of Protective Coatings - Method 3: Determination of dry film
thickness
ƒ
ASTM D7091.1 Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic
Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non- Ferrous
Metals
Important
The standards that govern film thickness measurements prescribe how to measure the DFT but do not
provide any acceptance criterion. As a result, the dry film thickness range should be clearly stated in the
specification as well as agree with the PDS and the coating manufacturer’s stated recommendations
Prior to Performing Measurements
Prior to performing any measurements, the inspector should verify that gauge has a current Certificate of
Calibration showing traceability to an independent testing laboratory or the equipment manufacturer.
Calibration is the process of testing and standardizing a gauge’s operation against a known reference
standard, then making the necessary adjustments (as required) to correct any out-of-tolerance conditions. All
gauge bodies and probes will include a Certificate of Calibration.
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It is performed by the equipment manufacturer, authorized agent, or an accredited calibration lab in a
controlled environment using a documented process. Calibration intervals are usually established based
upon experience, the work environment, and the owner’s quality assurance system. A one-year calibration
interval is a typical starting point suggested by manufacturers when the instrument is in regular use.
After the certificate of calibration is verified, inspectors should:
1. Locate and remove any contaminants from the gauge.
ƒ
Type I gauge – Pay particular attention to the calibrated magnet as it can attract magnetic filings and
can also be covered in coating residue from measurements taken on coatings that were not sufficiently
dry.
ƒ
Type II gauge – Pay particular attention to the probe as contaminants can become trapped, and it can
also be covered in coating residue from measurements taken on coatings that were not sufficiently dry.
It may also exhibit signs of wear if it has not been used correctly (e.g., dragged across a surface).
2. Check the functionality of the gauge.
ƒ
Type I gauge – Test that the dial is rotating correctly and can rotate beyond the expected thickness.
ƒ
Type II gauge – Examine the settings, including the language, battery charge, units of measurement,
measurement mode, calculation settings (zero, 1-point adjustment, 2-point adjustment, zero offset,
etc.), and paired devices.
Important
Inspectors should always verify the certificate of calibration and inspect the gauge settings (Type II) and
gauge body for damage and debris prior to taking measurements. These fundamental checks are the first
step of the DFT inspection process and should be performed regardless of the standard specified.
21.6 SSPC-PA 2
Verification of Accuracy
The basic measure of a coating thickness gauge’s performance is the accuracy with which the gauge takes
readings. Accuracy refers to how close a measurement reading is to the true (real or actual) coating thickness.
The process to verify the accuracy of the gauge is based on the principle that you check the gauge by
measuring a standard/shim of a known thickness before you use the same gauge to measure an unknown
thickness.
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Accuracy of Type I (magnetic pull-off) gauges is determined using certified coating thickness standards.
Certified standards are coated or steel test plates (containing an uncoated plate for zero reference) with
assigned thickness values near the expected dry film thickness to be measured. Unless explicitly permitted by
the gauge manufacturer, shims of plastic or of non-magnetic metals, which are acceptable for verifying the
accuracy of Type II gauges, are not used for verifying the accuracy of Type I gauges.
The accuracy of Type II gauges can be verified by measuring a certified coated thickness standard (described
for Type I gauges) or certified color-coded, plastic, or foil shims with assigned thickness values. Both Type I
and Type II DFT gauges should be verified for accuracy in accordance with the manufacturer’s instructions or
pre-programed procedures, using a one or two-point verification procedure. A one-point adjustment uses
one test plate or shim, while the use of two test plates or shims spanning the range of intended use is
considered a two-point adjustment.
DFT gauges should be verified for accuracy prior to and at the end of each work shift. If the same gauge,
reference standard, and method of verification are used throughout a job, they need to be recorded only
once. If the gauge is dropped or suspected of giving erroneous readings during the work shift, recheck its
accuracy. Also, during periods of high usage, the inspector may need to verify accuracy more often (hourly)
when a large number of measurements are being obtained. The stated value of the standard and the
measured value must be recorded each time accuracy is verified.
Important
Certified standards and shims are created and measured using equipment traceable to the National
Institute of Standards and Technology (NIST) or recognized national laboratory. A Certificate of Calibration
will be included with all certified test equipment.
Verification of Accuracy: Type I Gauge
The accuracy of Type I gauges are verified using
certified coated metal plates having at least one
thickness value within the expected range of use. For
example, if the specified dry film range is 10 - 12 mils
(254 - 305μm), the inspector would select a test plate
that is somewhere between the 10 - 12 mils specified
range, ideally 11 mils (279 μm).
To verify the accuracy of a Type I gauge using a
one-point procedure:
1. Select the metal test plate/shim that is within the specified range of the thickness of the coating that will be
applied.
ƒ
Record the stated thickness value of the test plate/shim.
2. Measure and record the thickness of the test plate/shim.
3. Compare and record the thickness value measured with the thickness stated on the standard.
ƒ
12
If the reading falls within the coating thickness standard and the manufacturer’s stated gauge accuracy
(typically a tolerance of ± 5%), the gauge is considered accurate and ready for use.
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Chapter 21: Measuring Film Thickness
ƒ
Example: If the specification states a DFT range of 4-6 mils (101-152 μm), you would select a 5 mil (127
μm) shim. If the manufacturer states a tolerance range of 5%, then the acceptable accuracy range of the
gauge is 95% to 105% of 5 mils (127 μm), meaning that a gauge reading between 4.7 mils to 5.25 mils
(119-133 μm) is operating accurately.
–
ƒ
Note: While it is very unlikely that a Level I inspector would need to perform these calculations,
further guidance can be found within ASTM D7091 section 7.3.
If the gauge reading is outside of the combined accuracy of the coating thickness standard and the
manufacturer’s stated gauge accuracy, it should not be used. As, Type I gauges cannot be adjusted in
the field. The instrument should be returned to the manufacturer or authorized agency for calibration.
If a two-point accuracy verification procedure is adopted, the inspector will conduct the same process used
for a one-point procedure except using two test plates – one slightly below and one above the intended range
of use. For example, if the range of the applied coating is between 4-6 mils (101-152 μm), then the inspector
will select a 2 mil (50 μm) and an 8 mil (203 μm) set of coated standards or shims.
Base Metal Reading (BMR) Adjustment
All DFT gauge (both Type I and II) readings are
influenced by changes in substrate shape,
composition, and surface roughness. When a DFT
gauge is placed on a prepared (abrasive blast
cleaned) substrate, the gauge will display a reading,
even though no coating is present. DFT gauges
measure from the magnetic plane of a roughened
surface which is partway into the peak and valley
pattern of the surface profile. This ensures that the
minimum coating thickness required by the specification is applied over the peaks of the surface profile,
eliminating the chance of pinpoint rusting. However, SSPC-PA 2 requires that dry film thickness is measured
from the top of the peaks of the surface profile. This inherent delta is known as the base metal effect and
must be accounted for when measuring film thickness.
Type I Gauges
As Type I gauges are commonly verified for accuracy using smooth-surfaced coating thickness standards (or
using a smooth zero plate), the inspector needs to account for the impact that the surface profile will have on
the gauge’s measurements separately. This is typically achieved by establishing a base metal reading or BMR
(SSPC-PA-2) or a correction value (ISO 19840) and then subtracting this offset value from DFT measurement
readings.
The inspector should keep in mind that the methods (SSPC PA- 2 and IS0 19840) outlined need to be
performed on the bare, prepared substrate. So, the inspector needs to coordinate with the contractor to take
the readings at the same time surface profile measurements are obtained (before coating application).
Alternatively, on some projects, the contractor will produce a reference panel that the inspector can use to
take these readings.
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Chapter 21: Measuring Film Thickness
Type II Gauges
Type II gauges are commonly verified for accuracy using calibration shims or foils on the prepared
(roughened) surface. As a result, the inspector does not need to account for the impact of the surface profile
separately, cutting steps out of the process. Due to the digital nature of Type II gauges, the inspector can verify
gauge accuracy and, if necessary, simultaneously adjust the gauge for the impact of the surface profile as part
of the same process. This eliminates the need to measure and deduct BMR.
Type II gauges can be adjusted in one of three ways: a 1-Point adjustment to zero for smooth surfaces or by
using a 1-point or 2-point adjustment to a known thickness for roughened surfaces. If you are measuring dry
film thickness on a smooth, flat surface, the only verification of accuracy you need is to ensure that the gauge
is reading “zero” on the uncoated test plate or surface. Note that there are some DFT gauges that are factory
calibrated to predetermined surface profiles. Such instruments do not require adjustment.
Important
It is important to highlight that the inspector is not establishing the surface profile, rather they are
measuring the effect that the profile (surface roughness) will have on the selected DFT gauge. If you were
to deduct the actual surface profile from the coating thickness readings, the actual coating thickness
would be understated. If the BMR is not accounted for, the actual coating thickness would be overstated.
Adjustment - Type I Gauge Only
When using a Type I DFT gauge in accordance with
SSPC-PA 2, the inspector must determine the impact
that the roughened substrate will have on the
gauge’s readings. This is achieved by obtaining a
Base Metal Reading (BMR).
To obtain the BMR, the inspector will:
1. Perform 10 arbitrarily spaced measurements
across the bare, roughened substrate using the
Type I gauge.
ƒ
Record each reading.
2. Average the 10 readings to determine the BMR value.
3. Record the BMR value for later use.
The BMR value represents the effect of the roughened substrate on the gauge’s readings. Later in the
measurement process, the BMR value will be subtracted from the “spot” measurements in order to report the
thickness of the coating layer(s) over the surface profile.
Important
The BMR will not change significantly across a structure as long as similar blast cleaning equipment,
abrasive size, and abrasive type are used. The BMR is also typically a small factor, usually 8 to 20 μm (0.3 to
0.8 mils) but can be outside this range.
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Chapter 21: Measuring Film Thickness
One-Point Adjustment Procedure - Type II
Gauge
Accounting for the accuracy of the gauge and
adjusting for BMR is completed in one step with Type
II gauges. While SSPC-PA 2 allows for a one-point or
two-point adjustment procedure, the one-point
procedure is more prevalent in the field and will be
the focus here. A one-point adjustment involves
fixing the instrument’s calibration curve at one point
after taking several readings on a single coating
thickness standard/shim or reference sample.
To perform a one-point adjustment per SSPC-PA 2, the inspector will:
1. Select a single shim with a thickness at or close to the expected film thickness and record the thickness
value of the shim.
ƒ
For example, if the specified film thickness is 3 – 6 mils (76 – 152 μm), then the inspector could select a
shim that measures 4 mils (101μ).
ƒ
If there isn’t a shim that falls within the specified range, then it is generally accepted practice to select a
slightly thicker shim than the maximum DFT.
ƒ
Note that shims can also be “stacked” on top of each other if the shims are not thick enough but need to
be positioned, so labels do not overlap.
2. Verify the thickness of the shim with a micrometer (if required) and record the reading. Note that SSPC-PA 2
does not require the verification of shims. However, it is considered a best practice.
ƒ
This is often performed as shims can become damaged or worn over time, altering their actual
thickness from what is listed on the label.
ƒ
If the shim measures outside of its stated value or is visibly damaged, it should be discarded.
3. Select the one-point adjustment option within the calibration menu.
ƒ
This option may be abbreviated, e.g., “1 pt. Adj” or “Rough 1-point”.
4. Place the shim on the roughened surface or on a blasted test surface with a similar profile and measure its
thickness.
ƒ
The average of 10 readings on the shim is sufficient to allow for the statistical variation in the blast
profile.
5. Compare the gauge reading to the shim’s measured thickness (from Step 2).
ƒ
If the readings match, the gauge is accurate and ready for use.
ƒ
If the readings do not match, the gauge needs to be adjusted to match the verified thickness of the
shim. To adjust the gauge, increase or decrease the numerical reading until it matches the shim’s
measured thickness. Repeat the process to ensure until the gauge reading matches the stated
thickness of the shim.
6. Repeat Steps 3-5 until the gauge is performing accurate measurements and ready for use.
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Chapter 21: Measuring Film Thickness
Important
Note that some Type II gauges cannot be adjusted to account for the impact of surface roughness. In such
cases, the inspector will need to follow the Type I method (verify accuracy and then obtain a Base Metal
Reading).
Measuring Dry Film Thickness
Film thickness can vary greatly across a coated
surface. Consequently, obtaining a single DFT gauge
reading will not be sufficient to determine the DFT of
the wider measurement area. Under SSPC-PA 2, the
number of readings that the inspector must perform
depends on the size of the coated area.
SSPC-PA 2 divides the coated area into 100 sq. ft.
(9.29 sq. m) sections, referred to as measurement
areas. The number of measurement areas that the inspector will perform gauge readings in is dependent on
the total surface area of the asset being coated.
If the asset is:
ƒ
Less than 300 ft2 (30 m2) – Measure each 100 ft2 (10m2) area.
ƒ
Between 300 to 1,000 ft2 (30 m2 - 100 m2) – Arbitrarily select and measure three 100 ft2 (10m2) areas.
ƒ
Greater than 1,000 square feet – Arbitrarily select and measure three 100 ft2 (10m2) areas.
–
Plus, one additional area (100 ft2 or 10m2) for each additional 1,000 ft2 (100 m2).
Before we examine the number of measurements performed in each area, the inspector must first
understand the difference between “gauge readings” and “spot readings.”
ƒ
A gauge reading is the measurement value obtained each time the probe of a thickness gauge comes
in contact with the surface.
ƒ
A spot measurement is when a group of three gauge readings is taken within a 1.5 in. (3.8 cm)
diameter circle area, and then their values are averaged.
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Chapter 21: Measuring Film Thickness
To measure a 100 ft2 (9.29 m2) area, the inspector performs five
“spot” measurements. A “spot” measurement is performed by
taking three gauge readings within an area that is ≈ 1.5 in. (4
cm) in diameter. So, for each selected 100 sq. ft. (10 m2), the
inspector will identify 5 test sites and then take 3 readings at
each site, culminating in a minimum of 15-gauge readings
within the area. Note that any unusually high or low gauge
readings that are not repeated consistently should be
discarded.
The three readings within each spot are then averaged to
determine the Spot Measurement. The inspector should
document each individual gauge reading unless they are using
a Type II gauge with the capability to store the readings and
access them later.
Important
Complex structures like steel beams and girders require additional measurements. Refer to the
appendices of SSPC-PA 2 for more information.
Calculating DFT
To determine the DFT of the wider measurement
area per SSPC-PA 2, the inspector averages the five
“spot” measurements. However, if the impact of the
surface roughness was not accounted for when
adjusting the gauge, then its impact must be
factored into these calculations. This is achieved by
subtracting the BMR from each of the “spot”
readings prior to averaging them. Both processes
are outlined below.
Mentor Tip
Remember that when averaging any set of numbers, the average cannot be greater than the largest
number or less than the smallest.
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Chapter 21: Measuring Film Thickness
Type I gauge
Type II gauge
To calculate the DFT of the measurement area:
To calculate the DFT of the measurement area:
1. Average the three gauges readings within each
spot to determine the spot measurement.
1. Average the three gauges readings within each
spot to determine the spot measurement.
2. Subtract the Base Metal Reading (BMR) from each
spot measurement to determine the adjusted
spot readings.
2. Average the five spot measurements to
determine the DFT of the measurement area.
3. Average the five spot measurements to
determine the DFT of the measurement area.
Remember that a BMR is not required when
measureing with a Type II gauge.
Note that the above calculations are repeated for each measurement area.
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Chapter 21: Measuring Film Thickness
Tolerance – Key Terminology
Tolerance is the permissible limit or variation in a
measurement. In other words, it is the pre-determined margin
of error that a measurement is allowed in order to still conform
with the specification. Tolerance is expressed as ±. When
measuring the Dry Film Thickness of an applied coating,
tolerance is applied at two key stages in the process. The first
occurred during the verification of accuracy, and the second
occurs when determining if the recorded DFT measurements
conform with the standard’s requirements.
Verifying Conformance with the Specification
For many inspection tasks, verifying conformance is as straightforward as checking if the obtained readings
fall within the range listed in the specification. Determining if the DFT of an applied coating material is in
conformance with a specification is a more complex process. SSPC-PA 2 outlines two criteria that the DFT
readings must meet for the applied coating to be in conformance with the specification.
Conformance criteria:
ƒ
Each spot measurement shall be within the adjusted DFT range.
ƒ
The area measurement shall be within the specified DFT range.
Conformance Criteria 1
To fulfill the first conformance criteria, each spot measurement must be within the adjusted DFT range. In this
context, the “adjusted” DFT range refers to the DFT range after the permissible tolerance has been applied.
SSPC-PA 2 breaks down the degree of tolerance allowed into five restriction levels. These levels can be seen in
the Coating Thickness Restriction Levels table below, with Level 1 being the most restrictive and Level 5 the
least restrictive.
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Chapter 21: Measuring Film Thickness
Coating Thickness Restriction Levels
Thickness
Gauge Reading
Spot Measurement
Area Measurement
Minimum
Unrestricted
As specified
As specified
Maximum
Unrestricted
As specified
As specified
Minimum
Unrestricted
As specified
As specified
Maximum
Unrestricted
120 % of maximum
As specified
Minimum
Unrestricted
80% of minimum
As specified
Maximum
Unrestricted
120% of maximum
As specified
Minimum
Unrestricted
80% of minimum
As specified
Maximum
Unrestricted
150% of maximum
As specified
Minimum
Unrestricted
80% of minimum
As specified
Maximum
Unrestricted
Unrestricted
Unrestricted
Level 1
Level 2
Level 3 (default)
Level 4
Level 5
If SSPC-PA 2 is specified, but no restriction level is listed, then Tolerance Level 3 is automatically applied.
Under Restriction Level 3, each spot measurement must be within 80% of the minimum specified thickness
and 120% of the maximum specified thickness to be in conformance. As an example, if the DFT range for the
primer is specified as 1.2 – 3.2 mils (30 – 81 μm), then the adjusted range is 1.0 – 3.8 mils (25 – 97 μm) as 80% of
1.2 mils equals to 0.96 (rounded to1.0 mil), and 120% of 3.2 mils equals 3.8 mils.
In the table below, SSPC-PA 2 Restriction Level 3 has been applied to the readings. If you examine the table,
you will see that Spot 4’s adjusted reading is 1.1 mils which is outside the specified DFT range (1.2 mils
minimum) and is, therefore, not in conformance. However, when Restriction Level 3 is applied, the minimum
DFT is lowered to 1.0 mils, bringing Spot 4’s reading back into conformance.
Conformance Criteria 2
To fulfill the second conformance criteria, the DFT of the wider measurement area must be within the DFT
range listed in the project’s specification. Restriction Levels do not apply when determining if the DFT of the
entire measurement area is in conformance. In the table above, you will see that the DFT for Measurement
Area 1 is 1.4 mils. The specified DFT range is 1.2 to 3.2 mils, so are area average of 1.4 mils is in conformance.
The inspector can sign off on this area and move on to the next section.
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Chapter 21: Measuring Film Thickness
Important
If a single DFT value is specified instead of a range, then the minimum and maximum thickness for each
coating layer shall be ± 20% of the stated value. For example, a DFT of 10 mils would convert to a range of
8 – 12 mils.
SSPC-PA 2 contains 10 appendices. These appendices are non-mandatory unless specified. They describe
alternative methods to perform parts of the DFT measurement process and provide guidance on how to
implement the standard when different scenarios are presented (e.g., measuring DFT on a complex shape).
The inspector should familiarize themselves with these appendices prior to implementing the required
standard.
The 10 appendices include:
ƒ
Appendix 1 – Numerical Example of Average Thickness Measurement and Illustration of the Procedure for
Determining the Magnitude of A Nonconforming Area
ƒ
Appendix 2 – Methods for Measuring Dry Film Thickness on Steel Beams (Girders)
ƒ
Appendix 3 – Methods for Measuring Dry Film Thickness for A Laydown of Beams, Structural Steel, And
Miscellaneous Parts After Shop Coating
ƒ
Appendix 4 – Method for Measuring Dry Film Thickness on Coated Steel Test Panels
ƒ
Appendix 5 – Method for Measuring Dry Film Thickness of Thin Coatings on Coated Steel Test Panels That
Have Been Abrasive Blast Cleaned
ƒ
Appendix 6 – Method for Measuring the Dry Film Thickness of Coatings on Edges with Type II Gages
ƒ
Appendix 7 – Method for Measuring Dry Film Thickness on Coated Steel Pipe Exterior
ƒ
Appendix 8 – Examples of the Adjustment of Type II Gages Using Shims
ƒ
Appendix 9 – Precaution Regarding Use of the Standard for Coating Failure Investigations
ƒ
Appendix 10 – Procedure for Obtaining a Greater Population of Thickness Measurements Using Type II
Gage Continuous Read/ Scanning Probe Technology
21.7 ISO 19840
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Chapter 21: Measuring Film Thickness
Adjustment of the Instrument - Type I and II
Per ISO 19840, Section 6.2, to verify the accuracy of both Type I and Type II gauges, you will undertake a
two-point verification procedure if you have access to a sample of the bare, prepared (uncoated) substrate. A
two-point adjustment fixes the instrument’s calibration curve at two known thicknesses.
This procedure requires the use of a zero-test plate and two traceable standards (shims or coated test plates),
one below and one above the specified DFT. As an example, if the specified film thickness is 3 – 6 mils (76 – 152
μm), then the inspector could select a shim/plate that measures 2 mils (51μ) and one that measures 7 mils
(175 μm).
To perform a two-point verification per ISO 19840, the inspector will:
1. Zero the gauge on a smooth, uncoated test plate (zero test plate) per the manufacturer’s instructions.
ƒ
Type I gauges: If a Type I gauge will not ‘zero,’ it should be sent for calibration.
ƒ
Type II gauges: If a Type II gauge will not ‘zero,’ it can be adjusted using the “Zero” option within the
gauge’s calibration menu.
2. Select a shim/test plate that is higher (thicker) than the specified DFT and one that is lower (thinner).
ƒ
Note that shims can also be “stacked” on top of each other if the shims are not thick enough but need to
be positioned so labels do not overlap.
3. Measure the thickness of the thinner shim/test plate and record the reading. If the readings match (within
the permissible tolerance), the gauge is considered accurate and ready for use.
ƒ
Note always consult the gauge’s instruction manual as some manufacturers may require that the
thicker shim be measured first, followed by the thinner shim.
ƒ
Type I gauges: If the reading does not match the test plate’s thickness (within the manufacturer’s
permissible tolerance range), the gauge should not be used until it is repaired and re-calibrated by the
manufacturer or authorized agency. ISO 19840 states that Type I gauges that have a a fixed scale
graduation should only be used when a lower level of accuracy can be accepted. They can only be
adjusted at one particular point on the scale, and this adjustment will have a limited effect on
calibration over the full range.
ƒ
Type II gauges: Select the two-point adjustment option within the calibration menu and place the shim
on the prepared substrate. If the reading of the shim does not match its assigned thickness value,
adjust the scale reading to the value of the shim. To adjust the gauge, increase or decrease the
numerical reading using the relevant buttons.
4. Repeat the procedure for Step 3 using the thicker shim.
5. Verify the accuracy of the gauge by measuring an intermediate-value shim on the roughened surface.
ƒ
An intermediate value shim is one that sits within the specified DFT range.
ƒ
If the measured thickness matches the shim’s thickness, the gauge is ready for use.
Important
ISO 19840 does not explicitly require the inspector to verify the thickness of the selected shims with a
micrometer. However, it is considered best practice and, when possible, should be performed. Further,
while ISO 19840 outlines that the thinner shim should be measured and then the thicker, this order may
change depending on the manufacturer’s guidelines.
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Correction Values
When determining the specific correction value when
the surface roughness is known and was measured
using comparators:
1. Refer back to the previous inspection records to
determine the surface profile grade recorded
earlier in the process.
2. Match the surface profile grade to a Correction
Value within the Correction Value Table.
ƒ
E.g., A “medium” grade profile has a correction value of - 25 μm / - 1.0 mils.
Surface profile per ISO 8503-1
Correction value (µm)
Correction value (mils)
Fine
10
0.4
Medium
25
1.0
Coarse
40
1.6
Unknown
25
1.0
3. Record the Correction Value.
ƒ
Note: The value will later be subtracted from the DFT gauge readings or input into the gauge (Type II
only) using the zero offset calibration option.
If you don’t have access to the prepared (uncoated) substrate, you can use the “Zero Offset” method, available
on some Type II gauges. ISO 19840 states that if the surface profile is unknown, the inspector should calibrate
on smooth steel (preferably of the same type as the substrate) and then subtract the predefined correction
value from the measurement taken on the coated surface. Some gauges are pre-programmed to include
correction values that can be selected prior to measurement. When used, the inspector does not have to
manually subtract the correction value from readings later in the process.
ISO 19840 outlines two additional methods for determining correction values:
ƒ
If the surface profile is unknown or has not been measured, a correction value of 25 μm (1 mil) can be
used to offset the impact of the surface roughness.
ƒ
If a sample showing the surface profile is available and the profile is not in accordance with ISO 8503-1, the
correction value shall be determined in accordance with Annex D.
Annex D is used when the inspector needs to determine a specific correction value on the roughened surface
with the particular dry film thickness instrument being used. This process is very similar to the Base Metal
Reading (BMR) process used under SSPC-PA 2. Annex D states that a foil/shim of approximately 125 μm
thickness (but not less than 115 μm or greater than 160 μm) should be placed on the roughened surface. Take
10 measurements at different points on the blast-cleaned or roughened surface. Average the 10 readings
together and subtract the stated value (thickness) of the foil/shim to determine the correction value.
23
CIP Level 1
Chapter 21: Measuring Film Thickness
Measuring Dry Film Thickness
Film thickness can vary greatly across a coated
surface. Consequently, obtaining a single
measurement will not be sufficient to determine the
DFT of the wider test area. Under ISO 19840, the
number of measurements to be taken in an
inspection area is outlined within the standard’s
Sampling Plan.
ISO 19840 considers the entire structure to be one
measurement area if the project’s specification does not divide the structure into specific inspection areas,
except when the coated area is greater than 1,000 m2 or m. Areas larger than 1,000 m2 or m should be broken
down into separate, smaller measurement areas.
Sampling Plan
Area/length of inspection area
m2 or m
Minimum number of
measurements
Maximum number of
measurements allowed to be
repeated
up to 1
5
1
above 1 to 3
10
2
above 3 to 10
15
3
above 10 to 30
20
4
above 30 to 100
30
6
above 100*
add 10 for every additional 100
m2 or 100 m or part thereof
20% of the minimum number of
measurements
*Areas above 1000 m2 or m should be divided into smaller inspection areas.
Inspectors should note that the Sampling Plan outlines the minimum number of gauge readings that should
be performed. The number of readings should be increased, as appropriate, for inspection areas that are
difficult to access or have complex configurations (e.g., stiffeners, brackets, supports, piping). In addition, ISO
19840’s uses “m” or “m2” to define measurement areas. This is particularly useful when measuring long, thin
structures like pipelines or structural supports (beams, girders, etc.).
24
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Chapter 21: Measuring Film Thickness
Important
Repeat Measurements
Unlike other DFT standards, ISO 19840 limits the number of repeat measurements that can be performed.
When, during a series of measurements, an individual dry-film thickness value does not meet the
conformance criterion, a repeat measurement no more than 10 mm (0.4 ″) from the point of the first
measurement shall be performed. If the second measurement meets the conformance criteria, the first
value is rejected and replaced by the result of the repeated measurement. If the repeated measurement
does not meet the conformance criterion, it cannot be used to replace the first value. For maximum
numbers of repeated measurements allowed within an inspection area, refer to the Sampling Plan. Note
that the number of replaced measurements shall be indicated in the inspection test report.
Calculating DFT
To determine the DFT of the wider measurement
area per ISO 19840, the inspector averages the
individual gauge readings. However, if the impact of
the surface roughness was not accounted for when
verifying the accuracy of the gauge, then its impact
must be factored into these calculations. This is
achieved by subtracting the Correction Value from
each of the readings prior to averaging them all
together. Both processes are outlined below.
Type I Gauges
To calculate the DFT of the measurement area:
1. Subtract the Correction Value from each gauge
reading to determine the adjusted gauge
readings.
2. Average the adjusted gauge readings to
determine the DFT of the measurement area.
25
CIP Level 1
Chapter 21: Measuring Film Thickness
Type II Gauges (if the Correction Value was preprogrammed into the gauge)
To calculate the DFT of the measurement area:
1. Average the gauge readings to determine the DFT
of the measurement area.
Important
Note that the correction value is applied once to every reading, no matter if the coating consists of a single
layer or multiple layers. As a result, if a top coat is applied over the primer, then the Correction Value will
also need to be subtracted from both the primer’s DFT readings and the combined primer and topcoat
DFT readings.
Conformance
ISO 19840 outlines four criteria that the DFT readings
must meet for the applied coating to be in
conformance with the specification.
Conformance criteria:
a. The arithmetic mean of all the individual dry-film
thicknesses shall be equal to or greater than the
nominal dry-film thickness (NDFT);
b. All individual dry-film thicknesses shall be equal to or above 80% of the NDFT;
c. Individual dry-film thicknesses between 80% of the NDFT and the NDFT are acceptable provided that the
number of these measurements is less than 20% of the total number of individual measurements taken;
d. All individual dry-film thicknesses shall be less than or equal to the specified maximum dry-film thickness. If
it is not specified, see ISO 12944-5.
If the acceptance criteria above are met, the measurement area is in conformance.
Important
ISO 19840 defines nominal dry film thickness (NDFT) as the dry-film thickness specified for each coat or
for the whole paint system to achieve the required durability.
ISO 12944-5 defines maximum dry film thickness as the highest acceptable dry film thickness above which
the performance of the paint or the paint system could be impaired
26
© NACE International
Chapter 21: Measuring Film Thickness
Annexes
ISO 19840 contains five annexes. These annexes are
only mandatory when agreed to or specified. They
describe alternative methods to perform parts of the
DFT measurement process and provide guidance on
how to implement the standard when different
scenarios are presented (e.g., measuring DFT on a
complex shape). The inspector should familiarize
themselves with these annexes prior to
implementing the required standard.
The five annexes include:
ƒ
Annex A – Method based on adjusting the instrument to known thicknesses on a rough surface
ƒ
Annex B – Multiple readings
ƒ
Annex C – Areas requiring special consideration
ƒ
Annex D – Determination of a specific correction value
ƒ
Annex E – Example of a test report form
27
CIP Level 1
Chapter 21: Measuring Film Thickness
Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. When using a wet film thickness gauge, the film thickness is reported as which of the
following?
A. The first tooth that has coating on it
B. The first tooth that has no coating on it
C. The last tooth that has no coating on it
D. The last tooth that has coating on it
2. Which of the following is an advantage of using a magnetic pull-off gauge?
A. It is intrinsically safe
B. It is more accurate than digital gauges
C. It can be used in small, hard to reach areas
D. It can store readings
3. You must take a measurement using a magnetic pull-off gauge. What is the minimum
recommended distance from the edge that you can reliably take a measurement?
A. 1 cm (.39 inch)
B. 2.5 cm (1 inch)
C. 6.35 cm (2.5 inch)
D. 2.5 mm (.10 inch)
4. Per ISO 19840, a two-point verification of a Type II gauge requires____________?
A. Selecting reference coated standards below and above the anticipated coating thickness
B. Selecting two reference coated standards representing the mid-range of the anticipated coating
thickness
C. Selecting reference coated standards that represent the minimum and maximum DFT specified
D. Recording two measurements of gauge accuracy against coated reference standards
28
© NACE International
Chapter 21: Measuring Film Thickness
5. Per SSPC-PA 2, how many gauge readings are required when measuring dry film thickness at
one spot on a steel surface?
A. One (1)
B. Three (3)
C. Four (4)
D. Five (5)
6. What is the total number of spot measurements required by SSPC-PA 2 in a 1,000 ft2 (100 m2)
area?
A. Five (5)
B. Twenty-five (25)
C. Ten (10)
D. Fifteen (15)
29
CIP Level 1
Chapter 21: Measuring Film Thickness
Self-Study Review
Answer the following questions for additional practice. To check your responses, refer to the
Answer Key in the Reference tab.
Pipeline Scenario
You have been instructed to measure the DFT of a recently repaired section of pipeline using a Type II gauge.
The specified DFT is 60 - 80 μm (2.4 – 3.2 mils) per SSPC-PA 2 Lv3 or ISO 19840.
1. If the surface area of the pipeline is 3 m2 (32 sq. ft.), how many DFT measurements do you
need to perform?
30
© NACE International
Chapter 21: Measuring Film Thickness
To the right are the readings you obtained while measuring the film thickness of the pipeline.
2. Based on the readings, what is the DFT of the measurement area?
Note: As the section of pipeline being coated is <9.3m2 (<100 sq. ft.), it is considered one
measurement area.
What does the ‘R’ next to reading 9 and 10 mean, and why doesn’t reading 3 have an ‘R’?
3. Based on the permissible tolerance, what is the adjusted DFT range?
Note, SSPC-PA 2 Tolerance Level 3 allows for 80% of minimum specified thickness and 120%
of maximum. ISO 19840 allows for a limited number of readings to be 80% of the minimum
specified thickness.
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CIP Level 1
Chapter 21: Measuring Film Thickness
4a.
Is each spot measurement within the adjusted DFT (60μm - 80μm)?
Is the DFT of the measurement area within the specified DFT range (48μm - 96μm)?
4b. Is the DFT of the applied coating, in conformance with the specification’s requirements?
Is the arithmetic mean of all the individual DFT
measurements ≥ the NDFT?
Are all individual DFT measurements equal to or above
80% of the NDFT?
Is the percentage of individual DFT readings between 80%
of the NDFT and the NDFT less than 20% of the total
number of measurements taken?
Are all individual DFT readings ≤ to the specified
maximum DFT?
32
© NACE International
Chapter 21: Measuring Film Thickness
5. Can the inspector report that the work is in conformance with the specification?
33
Chapter 22: Holiday Detection
Chapter 22:
Holiday Detection
22.1 Introduction
Learning Objectives
By the end of Chapter 22, students should be able to:
1. Accurately test for the presence of holidays using a low voltage DC detector.
2. Compare and contrast the three types of high voltage detectors.
Review: Holiday Testing
Holidays are an exposed area or discontinuity within
the coating film where part of the substrate remains
uncoated. These tiny voids can lead to premature
coating failure as they expose the substrate to the
atmosphere. The presence of the holiday completes
the corrosion cell by allowing an electrolyte to make
contact with the substrate. A few examples of
holidays include craters, pinholes, fisheyes, and
cracks. Most holidays are found on complex
structures or hard to access areas such as edges, corners, welds, bolts, nuts, inside holes, angles, etc.
Holidays within the coating film are detected with the use of low voltage or high voltage holiday detectors. The
type of holiday detector used is based on the total thickness of the coating system and the environment in
which it is used. Holiday detectors operate by forming an electric circuit when an exposed portion of the
substrate is detected. As a result, they will only work on non-conductive coatings that are applied to a
conductive substrate, such as steel or concrete. For example, epoxy coatings applied to steel can be tested for
holidays, while a zinc-rich coating applied to the same steel could not (zinc is a conductive metal in the
coating).
Holiday detection is typically performed after the final coat has been applied but within the recoat interval
(period), in case repair of the coating film is required. Coatings that are not cured may show false holidays.
Any holidays detected should be repaired and retested to ensure that repairs were successful.
1
CIP Level 1
Chapter 22: Holiday Detection
Operating Principle: Low Voltage
Detectors
Holiday detectors use electricity, and more
specifically, the formation of a closed circuit, to
locate discontinuities within the coating film. Most
coating materials are poor electrical conductors. As a
result, when a holiday detector is moved over the
coating, it will act as an insulator and block the
electricity’s path. Metal substrates are, however,
conductive to electricity.
Low voltage DC detectors operate by forming an electric circuit when the wet sponge is moved across the
coated surface. If a holiday is present, the water from the sponge will pass through the holiday and contact
the exposed steel. The water acts as a bridge, joining the detector to the conductive surface, allowing an
electric circuit or “loop” to form and electrons to flow. The electric current then flows from the detector’s
sponge through the conductive substrate back to the detector through the return cable/ground wire. This
causes the detector to signal, indicating the presence of a holiday in the coating film.
Concrete Substrates
Using holiday detectors over a concrete surface can be more challenging than using one over steel surfaces.
The central challenge is ensuring that the instrument is properly grounded. If there is exposed rebar or metal
protruding from the concrete, the ground wire cable should be connected directly to the reinforcing steel
rebar when possible. If no rebar or other metal object within the concrete is available, make a capacitance
ground connection to the concrete by clamping the ground wire to a wire mesh screen. Make sure the screen
is in contact with the concrete by placing a weighted cloth or sand-filled bag over the top.
An alternative is to drive a metal rod (or piece of rebar) into the ground nearby the concrete to at least the
depth of the slab, relying on the earth to conduct the electric current between the rod and the slab. However,
this should not be performed without written authorization. Wetting the concrete in the immediate area also
helps to establish continuity.
Test Methods
The focus of CIP Level 1 is on low voltage, direct current (DC) holiday detectors. However, there are also two
types of high voltage holiday detectors including:
ƒ
High voltage continuous or constant DC
ƒ
High voltage pulsed DC
2
© NACE International
Chapter 22: Holiday Detection
Low Voltage vs. High Voltage Detectors
As their names indicate, low voltage detectors operate at lower voltages, typically less than 90 volts, while high
voltage detectors typically operate between 500 – 35,000 volts. The lower voltage means that low voltage
holiday detectors are only able to detect holes in the coating film that go all the way through to the metal
substrate. In comparison, high voltage holiday detectors can detect weaknesses (thin areas) in the coating
that do not penetrate through to the metal substrate.
Low voltage holiday detectors are typically used on coating thicknesses up to 20 mils (508 microns), and high
voltage instruments can detect holidays in coatings of all thicknesses. It is important to note that high voltage
detectors are thickness-specific. As such, they can be adjusted to the proper inspection voltage for the coating
thickness being tested. It is recommended that you set the voltage test to the upper end of the specified DFT
range. Table 1 of NACE SP0188 contains suggested voltages that may be used as a guide. However, the
coating manufacturer’s instructions should always be consulted regarding the maximum voltage for the
applied coating.
A distinct advantage of low voltage detectors is that they are non-sparking and can, therefore, be used in
some intrinsically unsafe environments (e.g., inside water tanks, petroleum storage tanks). They also do not
damage the coating film when a holiday is detected. High voltage detectors, if used improperly, may cause
damage to coatings if the voltage is set too high. Some holiday detectors on the market today come equipped
with an automatic power drop. This feature prevents damage to the coating by cutting power to the unit when
the circuit is completed and a holiday is detected.
22.2 Low Voltage Holiday Detectors
Low Voltage DC Detectors: Overview
A low voltage DC detector is an instrument that
allows an inspector to detect discontinuities within a
coating’s film. These instruments are also referred to
as low voltage pinhole detectors or wet sponge
detectors. Low voltage detectors are also designed
to only work on coatings applied with a DFT of less
than 508 μm / 20 mils.
There are several manufacturers of low voltage
holiday detectors, but all of them operator on a similar principle. A low voltage detector consists of:
ƒ
Portable battery-powered electronic instrument
ƒ
Non-conductive wand with clamps
ƒ
Open-cell sponge (cellulose)
ƒ
Ground wire or “return” cable
The sponge is clamped to the end of a wand and is wetted with water. The holiday detector is grounded to the
substrate using a ground wire cable. Both the wand and the ground wire are attached to the detector.
3
CIP Level 1
Chapter 22: Holiday Detection
Standards
The following standards govern the use of low voltage holiday detectors:
ƒ
NACE SP0188 Discontinuity (Holiday) Testing of New Protective Coatings on Conductive Substrates
ƒ
ASTM D5162 Standard Practice for Discontinuity (Holiday) Testing of Nonconductive Protective Coating on
Metallic Substrates
ƒ
AS 3894.2 Site testing of protective coatings Non-conductive coatings - Continuity testing - Wet sponge
method
ƒ
ASTM G62-A Standard Test Methods for Holiday Detection in Pipeline Coatings
ƒ
BS EN ISO 28765 Vitreous and porcelain enamels. Design of bolted steel tanks for the storage or treatment
of water or municipal or industrial effluents and sludges
ƒ
ISO 8289-A Vitreous and porcelain enamels — low voltage test for detecting and locating defects
ƒ
ISO 14654 Epoxy-coated steel for the reinforcement of concrete
ƒ
JIS K 6766 Pinhole test method of lined films for corrosion prevention
Additional standards may be available for your region.
Method of Operation
The information below is a general description of how to test a coated surface for the presence of holidays
using a low voltage DC holiday detector. Always refer to the project’s specification, referenced standard, and
manufacturer’s instructions for more specific directions.
Step One: Assemble the Detector:
Before assembling the detector, always inspect the instrument to ensure it is free of damage and is in good,
safe operating condition. Next, insert the batteries into the detector or verify the existing batteries are
charged. Next, attach the ground wire to the base of the detector and then rotate the wire, typically clockwise,
to lock it in place. Next, connect the wand handle to the front of the detector, making sure to screw down until
the wand is firmly seated. Note that some holiday detectors have different wands for different accessories
(i.e., the roller sponge), whereas others have different brackets that attach the accessories to the end of the
wand. If required, attach the bracket, sponge holder, and sponge to the wand by using a threaded bolt.
4
© NACE International
Chapter 22: Holiday Detection
Step Two: Attach the Ground Wire to the Structure
Connect the ground wire to a bare (uncoated) section of the substrate using the spring-loaded clip. It is very
important that the clamp is in contact with the bare steel; otherwise, no pinholes or holidays will be detected,
even if they are there. When working with a concrete substrate, connect the clip directly to the reinforcing
steel (rebar) in the concrete where possible. If no rebar or other metal object within the concrete is available,
make a ground connection to the concrete by placing the bare ground wire on the concrete and anchoring it
down with a bag filled with damp sand.
Step Three: Saturate the Sponge
Saturate the sponge with clean tap water. Do not use distilled or deionized water, as pure water does not
conduct electricity as efficiently as tap water. Squeeze excess water from the sponge until it no longer drips.
ƒ
Wetting Agents / Surfactants
Wetting agents sometimes referred to as surfactants, can be added to the tap water to increase the
sensitivity of the test. They achieve this by reducing the surface tension of the water, which increases the
water’s ability to penetrate into the smallest of holidays. Wetting agents are typically used when
measuring coatings with a DFT of greater than 10 mils (254 μm), when the standard requires it, or when
recommended by the manufacturer. Non-sudsing wetting agents need to be added to tap water at the
ratio specified by the equipment manufacturer. For example, combine 7.4 ml (1 oz) fluid wetting agent
with 1 liter (1 gal) water. Wetting agents can leave contaminants on the surface that can interfere with
adhesion of topcoats or repair coats and may contaminate the stored product. So, if a wetting agent is
used, it must be completely removed by rinsing the holiday area prior to repair. Note that some standards
(e.g., SP0188: 3.2.8) do not allow wetting agents to be used when conducting holiday testing between the
coats of a multicoat system.
Step Four: Turn on the Detector and Select the
Voltage
Keeping the sponge clear of the surface, switch on
the detector. The inspector should then select the
required voltage per the manufacturer’s guidelines.
For example, a manufacturer may recommend using
9 V for coatings up to 12 mils (300 μm) thick and 90 V
for coatings up to 20 mils (500 μm) thick. Note that
some detectors do not have the functionality to
adjust their voltage; these detectors typically operate
at 67.5 V.
Step Five: Verify Continuity
Prior to testing for holidays, the inspector should verify continuity by ensuring that the detector unit is
properly grounded. To do this, the inspector will need to place the wetted sponge on an uncoated section of
the structure. If the detector’s alarm activates, the ground is adequate; if it does not, the inspector should
place the wetted sponge on the grounding clamp. If the alarm signals, the detector is operating properly; it’s
just that the ground contact is not adequate. In this case, the inspector will need to improve the ground wire
contact with the structure. If the detector does not signal when the inspector touches the wetted sponge to
the grounding clamp, the detector is not operating properly and should not be used.
5
CIP Level 1
Chapter 22: Holiday Detection
Step Six: Test for Holidays
Test the coated surface for holidays by dragging the wetted sponge across the surface at a maximum rate of
1 linear foot per second (30 cm/s). The inspector shall use a double stroke of the sponge over each area and
use sufficient pressure to maintain a wet surface. The inspector should avoid over saturating the sponge with
water because the rundown could complete the circuit across the coating surface to a holiday located several
feet away, thus giving false readings. This phenomenon is referred to in the industry as “telegraphing.” When a
holiday is found, the detector’s alarm will activate, and the sponge should be turned on end. The inspector will
then use the tip or the narrow end of the sponge to precisely determine the exact location of the holiday. Note
that the edges of the sponge can also be used to test for holidays on non-flat surfaces, such as inside corners
and around bolt heads and nuts.
Step Seven: Mark and Report any Holidays
Mark all detected holidays by circling them with a non-intrusive marker, such as white-calcium chalk or wax.
All holidays should be reported and repaired per the specification’s requirements. If a wetting agent is used,
clean the area before repair to remove the agent. If left on the surface can lead to premature failure of the
coating.
Usage Tips & Common Errors
To help ensure that accurate measurements are
performed:
ƒ
Attach the ground wire correctly
ƒ
Do not use distilled or deionized water – use tap
water only
ƒ
Ensure the batteries are charged or new
–
An output voltage drop of over 10% indicates
a weak battery
ƒ
Avoid under-wetting the sponge as this results in too little water to conduct electricity correctly
ƒ
Avoid over-wetting the sponge as this leads to telegraphing, when an electrical current travels through a
moisture patch to a discontinuity outside the test location, causing an erroneous discontinuity test result
ƒ
Always keep the sponge in contact with the surface
ƒ
Move the sponge at the correct speed across the testing surface
–
Maximum of 30 cm/s (1 linear ft/s) double stroke
ƒ
Perform occasional checks to see if the detector is operating properly
ƒ
Be aware that retained solvent in the coating film can cause erroneous indications (false holidays) during
testing
ƒ
Verify cleanliness when testing is performed between coats
ƒ
Use only approved wetting agents
ƒ
Ensure the cleanliness of the sponge. A dirty sponge can reduce current flow
6
© NACE International
Chapter 22: Holiday Detection
Calibration
All holiday detectors should come with a Certificate of Calibration. Once in service, instruments are typically
re-calibrated every 12 months by either the manufacturer or an authorized lab. Note that selecting the proper
voltage is critically important to maintaining accuracy when detecting holidays. Common voltages include 9,
67.5, 90, and 120 V. The required voltage may be specified in various standards, based on the thickness of the
applied coating or per the manufacturer’s instructions. Some holiday detectors have an internal calibration
and voltage check in which the instrument will shut down if the output voltage does not match the voltage
selected by the operator.
22.3 High Voltage Holiday Detectors
A high voltage (in excess of 800 V) holiday detector is
an electronic device used to locate discontinuities in
non-conductive coatings. They are known as spark
testers because of the spark they give off whenever a
holiday or coating discontinuity is found. Setting the
proper voltage is critical because too high a voltage
on a coating that is too thin may actually produce a
holiday in the coating film rather than test for it. An
advantage of high voltage instruments as compared
to low voltage is the elimination of the possibility of
telegraphing.
High voltage detectors use metal bristles, rubber, or coil electrodes instead of a sponge. The exploring
electrode is attached to the end of a wand, and the unit is grounded to the substrate using either a ground
wire clip or by allowing the ground wire to drag along the earth (provided the structure is grounded to earth).
When dragged across a coated surface (at a rate up to 0.3 m/s or 1 ft/s), the unit will throw a spark through the
air gap, sounding an alarm when a holiday is detected.
There are two main types of high voltage detector, the constant direct current (DC) and the pulsed direct
current (DC). As the name suggests, a constant DC holiday detector discharges high voltage continuously. A
disadvantage of constant current instruments is that they can cause false readings due to the current
spreading out along the pipe, making it difficult to identify the exact location of the holidays. A pulsed DC
detector discharges an adjustable and regulated ‘pulsed’ or “cycling” type of high voltage. Pulsed instruments
are more commonly used as they are easier to ground, have better battery life, and are safer to operate than
continuous pulse.
High voltage DC instruments are typically used on:
ƒ
Concrete substrates
ƒ
Dielectric (insulation type) coatings
ƒ
Thick coatings and linings (rubber)
ƒ
Plastic or fiberglass coatings that could become electrostatically charged
ƒ
Non-conductive coatings (Zinc primer or metalized coatings)
ƒ
Surfaces contaminated with moisture or dirt as the pulsing limits telegraphing
7
CIP Level 1
Chapter 22: Holiday Detection
Standards
There are numerous standards that govern the use of high voltage holiday detectors, depending on coating
and substrate type, including:
ƒ
ASTM D5162, Standard Practice for Discontinuity (Holiday) Testing of Nonconductive Protective Coating on
Metallic Substrates
ƒ
ASTM D4748, Standard Test Method for Determining the Thickness of Bound Pavement Layers Using
Short-Pulse Radar
ƒ
ASTM G62, Standard Test Methods for Holiday Detection in Pipeline Coatings
ƒ
NACE SP0274, High Voltage Electrical Inspection of Pipeline Coatings
ƒ
NACE SP0490, Holiday Detection of Fusion-Bonded Epoxy External Pipeline Coating of 250 to 760 µm (10
to 30 mil)
ƒ
NACE SP0188, Discontinuity (Holiday) Testing of New Protective Coatings on Conductive Substrates
ƒ
ISO 2746, Vitreous and porcelain enamels — High voltage test
Safety Considerations
The hazards of high voltage holiday testing cannot
be overly stressed. To ensure safe use of high
voltage detectors prior to testing:
ƒ
Make sure the structure to be tested is grounded
to earth
ƒ
Ensure the coating has cured prior to testing
ƒ
Always adjust the voltage setting according to the
specification
ƒ
Check that the coating is non-conductive and
that the substrate is conductive
ƒ
Check that the surface is dry as moisture can cause erroneous indications
ƒ
Check that the battery is charged and has proper voltage output according to the manufacturer’s
instructions
ƒ
Ensure that there are no solvent fumes present that can produce an explosive environment
–
Always test for flammable or explosive gas prior to using high voltage detectors in confined spaces
ƒ
Do not touch the probing electrode and keep the probe away from your body at all times when the
instrument is turned on
ƒ
Make sure adjacent workers are not touching the metal to be tested
ƒ
Never point the wand at another person
ƒ
Ensure that you are using the proper voltage setting for the anticipated DFT
ƒ
Never hold the ground wire when testing
ƒ
After the instrument has been turned off, always ground the probe before disassembling the unit to
ensure that any residual charge has dissipated
8
© NACE International
Chapter 22: Holiday Detection
Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. You have a 10 mils (254 microns) conductive coating on a non-conductive surface and need to
check for holidays. How would you perform the inspection?
A. Use a low voltage holiday detector
B. Visually, you cannot use a holiday detector
C. Use a high voltage DC holiday detector
D. Use a high voltage AC holiday detector
2. You are performing holiday testing early morning with dew on the pipe. The reason you may
get an erroneous indication is caused by __________________?
A. Telegraphing
B. Excessive film thickness
C. Broken ground wire
D. Dead battery
9
CIP Level 1
Chapter 22: Holiday Detection
Self-Study Review
Answer the following questions for additional practice. To check your responses, refer to the
Answer Key in the Reference tab.
1. General types of holiday detectors include:
2. Low voltage holiday detectors have a voltage of:
3. Describe low voltage holiday detectors:
4. High voltage DC holiday detector types include:
5. List at least 5 safety considerations that should always be observed when using high voltage
holiday detectors:
6. The type of high voltage holiday detector used for concrete is a:
10
© NACE International
Chapter 18: Measuring Environmental Conditions
Lab 4:
Measuring Dry Film Thickness (DFT)
Instructions
1. Measure the dry film thickness of the practice panel in accordance with SSPC-PA 2 using a:
ƒ
Type I DFT Gauge
ƒ
Type II DFT Gauge
–
DeFelsko PosiTector 6000
–
Elcometer 456
2. Document your results on the worksheets provided
Lab Worksheets
Note: Use metric or imperial units as appropriate.
1
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Type I Gauge: Magnetic Pull-off
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(Final measurement includes Primer + Finish Coat)
Spots
1
2
3
1
2
3
4
5
Total Film
DFT
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
2
© NACE International
Chapter 18: Measuring Environmental Conditions
Type II Gauge: Elcometer 456
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(Final measurement includes Primer + Finish Coat)
Spots
1
2
3
1
2
3
4
5
Total Film
DFT
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
3
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Type II Gauge: DeFelsko PosiTector 6000
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(Final measurement includes Primer + Finish Coat)
Spots
1
2
3
1
2
3
4
5
Total Film
DFT
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
4
© NACE International
Chapter 18: Measuring Environmental Conditions
Extra Practice Worksheets
Gauge Type:
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(Final measurement includes Primer + Finish Coat)
Spots
1
2
3
1
2
3
4
5
Total Film
DFT
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
5
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Gauge Type:
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(Final measurement includes Primer + Finish Coat)
Spots
1
2
3
1
2
3
4
5
Total Film
DFT
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
6
© NACE International
Chapter 18: Measuring Environmental Conditions
Gauge Type:
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(Final measurement includes Primer + Finish Coat)
Spots
1
2
3
1
2
3
4
5
Total Film
DFT
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
7
CIP Level 1
8
Chapter 18: Measuring Environmental Conditions
© NACE International
Chapter 18: Measuring Environmental Conditions
Lab 5:
Holiday Testing
Instructions
1. Answer all the questions in Section 1
2. Test the coating film on the panel for the presence of holidays using the Tinker & Rasor M-1 Low-Voltage DC
detector
3. After use, wipe the panel until clean and dry. Do not mark the panel
4. Answer all the questions in Section 2
Lab Worksheets
Section 1: Questions
What is the highest recommended DFT for proper use?
Can this holiday detector be used to find holidays on coated concrete?
 Yes
 No
How much surfactant should be added to the water?
Section 2: Holiday Testing
Date:
Time:
Brand and Model of Detector:
Type and amount of wetting agent/surfactant used:
Location of the holidays (if present):
Make a sketch in the box showing where you found holidays.
How many holidays did you find?
Comments or additional information (if any)?
1
CIP Level 1
Chapter 18: Measuring Environmental Conditions
Extra Practice Worksheets
Section 1: Questions
What is the highest recommended DFT for proper use?
Can this holiday detector be used to find holidays on coated concrete?
 Yes
 No
How much surfactant should be added to the water?
Section 2: Holiday Testing
Date:
Time:
Brand and Model of Detector:
Type and amount of wetting agent/surfactant used:
Location of the holidays (if present):
Make a sketch in the box showing where you found holidays.
How many holidays did you find?
Comments or additional information (if any)?
2
© NACE International
Chapter 22: Holiday Detection
Case Study Workshop
Instructions
Part 1
1. As a group, review the scenario and answer the questions
2. Record your answers in your student manual
Part 2
1. Nominate a spokesperson and be prepared to discuss your group’s answers during the
class review
2. Each group will present their case study and answers
Case Study #1
The Inspector arrives at the job site to find that the process tank
has already been blasted. The project’s specification requires a
1.5 - 2.5 mil (38 – 64μm) angular profile to be generated and for an
inorganic zinc primer to be applied.
When inspecting the prepared surface, the Inspector discovers
that while the profile is angular, it consistently measures between
4 - 5 mil (102 – 127μm).
1. What will occur if the primer is applied?
2. What should the Inspector do?
3. What is a potential solution?
1
CIP Level 1
Chapter 22: Holiday Detection
Case Study #2
A solvent-based, inorganic zinc coating was applied to a steel
bridge in the middle of summer. The application method was
airless spray.
During application, the coating dried before hitting the surface
resulting in poor adhesion, dry spray, and overspray.
1. What may have caused this problem?
2. How could this problem have been avoided?
2
© NACE International
Chapter 22: Holiday Detection
Case Study #3
The project’s specification requires the surface to be blast cleaned
to NACE No.2/SSPC-SP 10 (Near-White). While inspecting the
surface, the Inspector notices a small amount of mill scale.
When discussed with the contractor, he says, “That’s just staining.”
1. How could this conflict have been avoided?
2. What should the Inspector do?
3. If it is determined that mill scale is present, what needs to be performed prior to
application of the coating?
3
CIP Level 1
Chapter 22: Holiday Detection
Case Study #4
The specification states the following dry film thickness ranges:
ƒ
Primer: 5-7 mils
ƒ
Intermediate: 9-11 mils
ƒ
Topcoat: 4-6 mils
The thickness of the primer and intermediate coats measure
between 6-8 mils. You note that the PDS for the topcoat states that it cannot be applied in
thicknesses greater than 8 mils in a single application.
The contractor informs the Inspector that he will “make up” the required thickness with the
finish coat application in order to achieve the 18-24 mils, as specified.
1. What could have caused this problem?
2. What should the Inspector do?
4
© NACE International
Chapter 22: Holiday Detection
Elevated Water Tank
Lab
Lab Overview
The Elevated Water Tank Lab is designed to provide students with the opportunity to conduct an inspection in
a simulated environment. Your role is to use the equipment and testing surfaces provided to perform the
inspection, document the inspection data, and compare your inspection results to the specification
requirements. Any nonconforming areas of your inspection should be documented using the combined
Nonconformance and Corrective Actions report. Once the lab is completed, the class will reconvene to review
the results of your inspection.
Learning Objectives
By the end of this lab, students should be able to:
1. Demonstrate the ability to use a wide range of inspection equipment.
2. Document the inspection process using a Daily Report.
3. Document any nonconforming inspection items using a combined Nonconformance and Corrective
Actions Report.
Lab Instructions
1. Brief instructions are included with each of the 10 inspection tasks below. In addition, there are charts
throughout the worksheet for you to record your inspection results.
ƒ
To prevent bottlenecks using the inspection equipment, you may perform the inspection activities in
any order.
ƒ
Be certain to document the information directly on the inspection reports or record the information on
your worksheet and transfer the data to the inspection reports.
2. Compare the results recorded on your Daily Report to the excerpted project specification and assess
whether the results of your inspection conform to the requirements of the specification.
3. Fill out the combined Nonconformance/Corrective Actions Report by listing any nonconforming items from
your inspection and how you would resolve them.
1
CIP Level 1
2
Chapter 22: Holiday Detection
© NACE International
Chapter 22: Holiday Detection
Elevated Water Tank Lab Scenario and Specification
Excerpt
ACME Municipal Authority, located in a suburb of Perth, Australia, has
contracted Globex Coating Contractors for the removal and
replacement of the exterior coating of their 50-year-old elevated
potable water storage tank.
Your role is to inspect the work performed by the contractor
throughout the project, document the results on the attached Daily
Inspection Report, and note any nonconformities.
The information provided below was excerpted from the project specification:
Surface Preparation
Abrasive
Recyclable steel grit (conforming to SSPC-AB 2 and AB 3)
Abrasive Cleanliness
Per ASTM D7393; 6-8 pH
Surface Cleanliness
SSPC-SP 1 and NACE No. 3
Cleanliness of Compressed Air
Per ASTM D4285 (once/shift)
Minimum Blast Nozzle Pressure
785 KPa (110 psi)
Surface Profile
Angular; 50-87.5 um (2-3.5 mils); Coarse Profile
Minimum Salt Levels
=< 10 μs/cm
Environmental Conditions
Surface temperature a minimum of 5 °F (3 °C) above dew point
Exterior Coating
Environmental Conditions
Air and Surface Temperature: 50-120 °F (10 - 49 °C)
Relative Humidity: Maximum 85%
Surface temperature a minimum of 5 °F (3 °C) above dew point
Mixing Requirements
Complete kits as supplied using a shear mixing blade
Coating Type
Primer: ABC Company high solids epoxy (white color)
Topcoat: ABC Company high solids polyurethane (blue color)
Thinner
ABC Company T1
Thinning Requirements
Not to exceed 6% by volume
Application Equipment
Airless spray
Induction (Both Primer & Topcoat)
30 minutes at 77 °F
Pot life (Both Primer & Topcoat)
4 hours at 77 °F
Coating Thickness
SSPC PA-2 or ISO 19840 (for international classes)
Primer Thickness
125-175 um (5-7 mils)
Topcoat Thickness
37-50 um (1.5-2 mils)
Dry to Recoat Time
5 hours at 77 °F
Maximum Time Between Coats
30 days
3
CIP Level 1
Chapter 22: Holiday Detection
Elevated Water Tank Lab Inspection Task Worksheet
Task 1 | Initial Condition
When conducting a visual inspection of the tank, the inspector observed that the condition of the steel varied
across the surface of the tank. In some areas, the paint had peeled, and the substrate was exposed to the
atmosphere. These areas exhibited varying degrees of rust, mill scale, and pitting, as shown in the photos
below.
Document your observations on the Daily Report. In addition, using SSPC-VIS 1, record the initial condition
(rust grade) of each section.
Section A
Section B
Section A:
Section B:
Task 2 | Environmental Conditions
Prior to surface preparation commencing, the inspector measures the environmental conditions of the
surrounding area. Using the sling psychrometer and magnetic surface thermometer, measure the
prevailing environmental conditions outside, weather permitting. In the event of inclement weather,
measurements may be taken from inside the classroom.
Document your measurements on the Daily Report and, if needed, the Nonconformance/Corrective Actions
Report. Use either degree Celsius or Fahrenheit as appropriate for your region.
4
© NACE International
Chapter 22: Holiday Detection
Condition
Reading
Date
Time of day
Dry Bulb reading (air temperature or “t”)
Wet Bulb Reading (t’)
Depression of the Wet Bulb Thermometer (t-t’)
Relative Humidity
Dew Point Temperature
Surface Temperature
Spread between dew point and surface temperature
Task 3 | Soluble salts
Given the proximity of the tank to the beach, ACME Municipal Authority is concerned about the potential
presence of soluble salts on the surface of the tank. Answer the following questions and use the information
to fill out the Daily Report and, if needed, the Nonconformance/Corrective Actions Report.
1. What test methods could the inspector use to test for the presence and quantity of chlorides?
2. Where is the most likely place on the tank for soluble salts to accumulate?
3. The inspection test results indicated that the level of chlorides present was 40 μg/cm2. Are these
results acceptable per the specification?
4. What surface preparation methods can be used to remove chlorides??
5
CIP Level 1
Chapter 22: Holiday Detection
Task 4 | Surface Preparation
The inspector and the contractor together checked the condition of the blast equipment. A blotter test was
also performed to ensure the compressed air supply was not contaminated with oil or water. It was agreed
that the blasting system was in good working order.
The contractor cleaned the surface in accordance with SSPC-SP 1 as required by the specification. The surface
was then abrasive blast cleaned. The inspection revealed that the blasted surface was in conformance with
NACE No.3/SSPC-SP 6 for surface cleanliness.
Record the information in the appropriate fields on the Daily Report and, if needed, the Nonconformance/
Corrective Actions Report.
Task 5 | Abrasive Media
Prior to blasting, the inspector confirmed that the contractor had filled the
blast pot with the specified abrasive media. However, since the abrasive
media used on this project had been recycled many times, the media was
tested, per the specification, to ensure it did not contain any contaminants.
Shown is a photo of the vial test that the inspector took after the contents
had settled after shaking. Are the results of the test satisfactory or
unsatisfactory?
Test Results:
Task 6 | Surface Profile
Measure the surface profile on both sides of the practice panel using the comparators, manual micrometer
with replica tape, and the digital surface profile gauge. Record the surface profile measured using all three
instruments on the Daily Report, the Nonconformance/Corrective Actions Report. Use either mils or microns
as appropriate for your region.
Surface Profile Comparator
Type of Comparator Used (G or S)
Grade
Panel Side 1
Panel Side 2
6
© NACE International
Chapter 22: Holiday Detection
Manual Micrometer with Replica Tape
Surface Profile
Place Tape Here
Textex Tap 1
 mils /  µm
Panel Side 1
Testex Tape 2
Testex Tape 1
 mils /  µm
Panel Side 2
Testex Tape 2
Digital Surface Profile Gauge
Record Individual Gauge Readings (optional):
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
Panel
Side 1
Panel
Side 2
Side 1 Max:
Side 2 Max:
Surface Profile (average):
 mils /  µm
7
CIP Level 1
Chapter 22: Holiday Detection
Task 7 | Coating Application
The inspector arrives on the job site after the primer coat has been mixed and thinned but prior to
application. Primer coat application started at 10:20 a.m. and finished at 12:30 p.m.
After lunch that same day, the contractor mixed 10 gallons (two 5-gallon containers) of the specified topcoat
and thinned it 10% with ABC Company T10. The mixing and thinning ended at 2:15 p.m. The mixed paint
temperature is 58°F. The coating will be applied by airless spray.
The topcoat application began at 2:30 p.m. and was completed by 5:00 p.m. Record the information in the
appropriate fields on the Daily Report and, if needed, the Nonconformance/Corrective Actions Report.
Task 8 | Dry Film Thickness
Measure the dry film thickness on the provided practice panel using both the Type I: Magnetic pull-off gauge
and the Type II: Digital gauge.
Record your measurements using both instruments on the Daily Report and, if needed, the Nonconformance/
Corrective Actions Report. Use either mils or microns as appropriate for your region.
Type I Magnetic Pull-off Gauge:
DFT Measurements and Gauge Adjustments
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
8
Coated Metal Plates 
Plastic Shims 
© NACE International
Chapter 22: Holiday Detection
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(final measurement includes Primer + Finish Coat)
Spots
1
1
2
3
4
5
Total Film
DFT
2
3
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
9
CIP Level 1
Chapter 22: Holiday Detection
Type II Digital Gauge
DFT Measurements and Gauge Adjustments
BMR
Reading
1
2
3
4
5
6
7
8
9
10
Test Block
Value
Gauge
Reading
on Test
Average of 10 BMR Readings:
Serial Number of Gauge:
Does the gauge read within the stated accuracy of the manufacturer? (Yes or No)
Calibration Standard Serial Number:
Calibration standard used to verify gauge.
Check only one.
Coated Metal Plates 
Plastic Shims 
Primer Measurements
Spots
1
2
3
4
5
1
Primer DFT
Average of the
Spots
2
3
Average Before
Adjustments
Average After
Adjustments
Total DFT Measurements
(final measurement includes Primer + Finish Coat)
Spots
1
1
2
3
4
5
Total Film
DFT
2
3
Average of the
Spots
Average Before
Adjustments
Average After
Adjustments
10
© NACE International
Chapter 22: Holiday Detection
Task 9 | Coating Defects
The day after application, you observed that a portion of the
epoxy primer coat on the west side of the tank was not top
coated. You observe that the epoxy primer is still tacky and
has yellowish haze across portions of the surface.
Answer the following questions and use the information to fill
out the Daily Report and, if needed, the Nonconformance/
Corrective Actions Report.
1. As an inspector, what do you suspect occurred?
2. Does the presence of this substance put the project at risk? Why or why not?
3. How would you determine the nature of this substance?
4. What steps should the contractor take to prepare the surface for the topcoat application?
Task 10 | Low Voltage Holiday Detector
Determine if any holidays are present on the provided practice panel. Record your results on the Daily Report
and, if needed, the Nonconformance/Corrective Actions Report.
Pinholes Detected
Test Area
Date & Time of Test
No
Yes
11
CIP Level 1
Chapter 22: Holiday Detection
Notes:
12
© NACE International
Chapter 22: Holiday Detection
AMPP CIP
Date:
Daily Coating Inspection Report
Day of Week: S
Project/Client:
Location:
Inspector Name:
Inspector Signature:
Description of Area and Work Performed:
Copy to:
Attachments:
 Owner
 Contractor
 _______________
 Lab Worksheet
 NCR
 ______________
M
T
W
T
F
S
Contractor:
Hold Point Inspection Performed
 Weather and site conditions
 Pre-surface prep, initial condition and cleanliness
 Surface preparation monitoring
 Post surface preparation cleanliness and profile
 Mixing/thinning and application monitoring
 Post application and application defects
 Dry film thickness and curing
 Corrective actions follow-up and final inspection
Surface Conditions
 New
 Maintenance  Primer
 Steel  Concrete
 Galvanized
Condition Before Surface Prep:
Visual Standard/Guide:
 Paint
 Age
 Stainless Steel
 Dry
 Aluminum
 Cure
____________
 Rust Grade A  Rust Grade B  Rust Grade C  Rust Grade D
 SSPC-VIS 1
 SSPC-VIS 3
 ISO 8501-1
____________
 Mill Scale
 Pitting
 Laminations
 Weld Splatter
 Lead/Heavy Metal
 Oil
 Moisture
 Sharp Edges
 Rust
 ___________________
Test: ______________________________________________________
 Cl ______________________ µs/cm
Acceptable (Yes or No) _____________________
 Cl ______________________ µs/cm
2
 Painted Surface Condition ________________________________
Dry to:
 Abrasion
 Runs/sags
 Holidays
 Cracking
 Fisheyes/Cissing  Overspray
 Dry Spray
 pH ______________________
 Touch  Handle  Recoat
 _______________________________
Comments:
13
CIP Level 1
Chapter 22: Holiday Detection
Ambient Conditions
Air Temp
(Dry Bulb)
Wet Bulb
Depression
Wet Bulb
Relative
Humidity
Dew Point
Surface
Temp
Delta T
Surface Preparation
 Equipment Condition Check  Water/Oil Trap Check
 Solvent Clean
 Hand Tool
 Power Tool
Air Supply CFM: ________ Blast Hose Size: ________
 Abrasive Blast
 __________________________
Abrasive Type: ______________________________________
Oil Content or Dust Visible: (Y/N) ____________________
Nozzle Size/Pressure: _______________________ Kpa/psi
Air Supply Cleanliness: ________________________
Comments:
Surface Cleanliness and Profile Measurement
Cleanliness After Surface Prep:
 NACE No. 3/SSPC-SP 6  NACE No. 2/SSPC-SP 10  Unacceptable
Profile Specified: ____________________________________
Profile Check:

Gauge Type: ________________________________________
 Disc: Profile Achieved: __________ mils/µm  Tape: Profile Achieved: _________mils/µm
Gauge: Profile Achieved: ____________mils/µm
Surface Effect on DFT Gauge/BMR: _____________ mils/µm
Coating Application
 Stripe Coat
 Primer
 Intermediate
Product Name/Color: ________________________________
Quantity Mixed:
 Topcoat
Product Name/Color: _______________________________
Mix Method:
Quantity Thinner Added:
Mix Start Time: ___________________ Mix Finish Time: __________________
Pot Life: _____________________
 Conventional
Induction: ____________________
 Airless
 Touch-Up
 Brush
Strain/Screen:Y/N _________________
Paint Temperature: _______________ C/F
 Roller
 ________________
Comments:
Dry Film Thickness
Gauge Type: ______________________________________________________ Specified Standard: _____________________
Primer: Min: __________ mils/µm
Primer: Max: __________ mils/µm
Primer: Average: __________ mils/µm
Total: Min: __________ mils/µm
Total: Max: __________ mils/µm
Total: Average: __________ mils/µm
Primer DFT Specified: _____________________ mils/µm Topcoat DFT Specified: ______________________ mils/µm
Total System Average DFT: _________________________________________________ mils/µm
14
 Unacceptable
© NACE International
Chapter 22: Holiday Detection
AMPP CIP
Date:
Nonconformance/Corrective Actions Report
Day of Week: S
Project/Client:
Inspector:
Location:
Contractor:
Copy to:
Attachments:

Owner

Contractor

___________________

M
Stop Work Order
T
W

T
F
S
______________
Referenced Procedure, Specification or Standard:
Description and Location of Nonconformance:
Discussion and Recommendations:

Replace

Repair

Rework

Use As-is
Corrective Actions:
15
Chapter 23: Safety Awareness
Chapter 23:
Safety Awareness
23.1 Introduction
Learning Objectives
By the end of Chapter 24, students should be able to:
1. List potential safety hazards associated with basic coating inspection.
2. Describe the common personal protective equipment (PPE) used by the coating inspector.
3. Understand the role of the inspector when it comes to safety on the job site.
Inspector Mindset
It is essential for inspectors to be aware of the safety issues associated with
each process throughout the coatings project. The inspector, along with all
other workers, share responsibility for their collective safety and that of the
public. Everyone at the job site should keep a lookout for unsafe actions
and operations and report them to their supervisor, the engineer in charge
of the project, or the assigned safety personnel.
Coating inspectors are often employed on projects where the safety is left
under the control of the contractor. When working on projects in
permanent facilities, there may be a safety office or safety department
responsible for supplying additional information, support, and guidance to
workers about the hazards of the facility’s operations. On other projects the
coating inspector may be asked to independently monitor the project site to identify hazards and ensure
adequate controls are in place to minimize any risk of personal exposure.
The role of safety is unique for every project. For this reason, inspectors should always obtain specific
guidance on their role relative to safety from their employer prior to the start of any project and should never
undertake any safety role without the proper training and qualifications.
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Safety Disclaimer
This chapter is intended to educate inspectors
regarding safety issues they should be aware of on a
job site. While we address specific topics, it is not
possible to discuss everything necessary to ensure a
healthy and safe working environment in a course of
this nature. Thus, this information must be
understood as a tool for addressing workplace
hazards rather than an exhaustive statement of
workplace safety, which is defined by statute,
regulations, and standards.
There are several regulatory groups, commissions, organizations, and government departments that
establish and enforce safety standards around the world. It is vital that you familiarize yourself with all the
organizations responsible for regulating safety for the countries you work in and comply with their laws or
regulations. Coating inspectors can face general risks, personal risks, and legal risks. Violations can be ground
for sanctions, penalty, and even termination. The inspector is responsible for knowing what the risks are and
taking reasonable steps to avoid them.
23.2 Hazardous Materials
Hazardous Material
A hazardous material is a substance which, by
reason of being explosive, flammable, poisonous,
corrosive, oxidizing, irritating, or otherwise harmful,
is likely to cause death or injury. Heavy metals are
another form of hazardous materials that workers
may be exposed to.
Coatings, Acids/Caustics, and Abrasive
Dust
Coating Components
Most solvents are toxic to some degree, depending
upon the magnitude and duration of exposure, and
may burn when exposed to an ignition source.
Solvents can affect the body by skin contact, causing
reddening and swelling or triggering a response
from the immune system (like poison ivy) or pass
through the skin and be transported by the blood to
damage other areas of the body. Solvents can also enter the body by breathing, and once inhaled, the vapors
can pass from the lungs directly to the blood and travel to other body systems. Solvents can also be ingested,
which occurs when eating or drinking with contaminated hands or clothing.
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Pigments such as corrosion inhibitive pigments for example, lead and zinc chromates, are suspected
carcinogens and can be toxic in high doses. Even zinc, a mineral that is needed by the human body to maintain
good health, can be toxic in high doses. The binders used in some coatings, such as polyurethanes, are
potentially hazardous and may contain compounds that are strong irritants that cause allergic reactions of
the skin and/or respiratory system. When handling coating materials, always refer to the manufacturer’s SDS
to determine the appropriate personal protective equipment.
Acids/Caustics
In certain industries, e.g., pulp and paper mills, food and beverage processing plants, and water and
wastewater treatment plants, the inspector may become exposed to strong acids and/or caustics used to
prepare concrete/steel surfaces for coating. Both acids and caustics will cause eye damage and burn skin
upon contact. Appropriate personal protective equipment (PPE), including respiratory protection, gloves, eye
protection, and skin protection, should be used whenever working with or near acids or caustics. The PPE
required can be determined by consulting the product SDS.
Abrasive Dust
Airborne dust is generated during surface preparation activities and during blow-down of surfaces prior to
coating. Blast cleaning abrasives are generally chosen in part for their surface preparation performance
characteristics. However, recent studies have demonstrated that certain generic types of abrasives can
contain toxic materials that are released as the particles become fractured upon impact.
As a result, an inspector may be inhaling harmful dust particles without awareness since the dust that can
make it into the deep regions of the lungs (i.e., respirable) is too small to see. Breathing too much of any fine
dust (independent of its inherent toxicity) can irritate the linings of the throat and lungs, leading in extreme
cases to irreversible long-term effects. Other chronic lung diseases are also possible. For instance, the use of
silica sand as a blast cleaning abrasive is prohibited in many parts of the world due to the potential of silicosis,
a deadly lung disease. Respirators equipped with High-Efficiency Particulate Air (HEPA) filtration cartridges
must be fitted properly and worn to help avoid dust inhalation.
Toxic Metals
Many aged coatings contain lead, chromium,
asbestos, and other toxic metals. Also, abrasives
may contain harmful metals such as arsenic,
cadmium, silica, or beryllium. These metals may not
pose a hazard to humans while they are part of an
intact coating system but become hazardous when
they are “disturbed” during surface preparation and
maintenance painting activities.
Once these metals become fractured and the dust becomes airborne, they pose an inhalation hazard. Once in
the body, the toxic metals can affect the lungs, blood-forming system, and/or nervous system damage, among
other problems. The metals can also enter the body through ingestion if the inspector does not wear gloves or
does not wash their hands and face before eating, drinking, or using tobacco products. Basic personal
hygiene, respiratory protection, and protective clothing can prevent the hazards associated with these metals
from affecting the health of the inspector.
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Containment
Because most types of blasting involve forcibly
propelling media under high pressure against
whatever surface is being cleaned, some types of
abrasive media can create airborne particulate dust
and, as a result, the need for some level of
containment during the blasting process. The most
important consideration regarding particulate dust
is its level of toxicity, which depends upon three
interdependent factors: the substrate being
blasted, the contaminants being removed, and the type of blast media used.
Containment is the process of preventing pollution or contamination of the immediate site environment by
dust, debris, abrasives, chemicals, sprays, and other materials that have been applied to prevent corrosion.
The degree of containment required is directly proportional to the degree of toxicity present in the corrosion
preventive substance being applied. The more toxic that the dust, chemical, or spray present is, the greater
the level of containment that is required. Some types of containment systems used are total structure
enclosures, partial structure enclosures, and free-hanging enclosures.
The SSPC Guide 6, Containment of Debris describes methods of paint removal, containment systems and
procedures for minimizing or preventing emissions from escaping the work area, and procedures for
assessing the adequacy of the controls over emissions. The containment systems are categorized in up to four
classes per type of paint removal method, based on the extent to which emissions are controlled.
23.3 Hazardous Environments
Hazardous Environments
Industrial worksites (i.e. shipyards, fabrication,
production sites), in general are hazardous
environments, whether the industry is oil and gas
production, offshore, storage facilities, sewage
treatment plants, manufacturing, etc. In these
environments, coating inspectors are exposed to the
same hazards as blasters and painters, although the
magnitude or duration of exposure may be less.
Some of the most hazardous environments
encountered by inspectors include elevated and confined spaces, working in extreme hot or cold
environments and working near energized sources.
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Working at Heights
Falls from heights continue to be a leading cause of accidental death or injury in the workplace. Therefore,
inspectors should understand and use personal fall protection systems whenever exposed to elevated spaces
and/or fall hazards. Elevated spaces are any work environment that is higher than six feet (two meters). Some
countries may be stricter.
Fall protection can be provided with guardrails, safety nets, personal fall arrest systems (PFAS), positioning
devices, and/or warning systems. Where work platforms with guardrails are not feasible, personal fall arrest
systems must be used. A personal fall arrest system is a full-body harness that absorbs the shock in the event
of a fall and consists of:
ƒ
Anchorage Point
–
ƒ
Fixed structure to which PFAS components
are rigged
Body Harness
–
ƒ
Full body harness worn by the worker
Connector
–
ƒ
A lanyard or lifeline that connects the harness
to the anchorage device
Deceleration Device
–
Slows the fall before coming to a stop
Confined Spaces
Confined spaces are enclosed or partially enclosed spaces that have limited means for entry and exit but are
large enough and configured that a person can bodily enter and perform work. Confined spaces are not
designed for continuous entry, can be above ground or below ground, and lack climate control or ventilation.
Inspectors should be aware of the types of hazards they may encounter and if a permit is required to gain
access to the job site.
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Confined spaces can be classified as non-permit or permit required. Non-permit-required confined spaces do
not pose life, health, or safety hazards to the entrant. Permit-required confined spaces are those that:
ƒ
Contain or have the potential to contain a hazardous atmosphere
ƒ
Contain a material that has the potential to engulf an entrant
ƒ
Has an internal configuration such that an entrant could be trapped or asphyxiated
ƒ
Contains any other recognized serious safety or health hazard
Conditions within a confined space can change very quickly, and the rescue of a worker is extremely difficult.
An estimated 60% of fatalities in confined spaces have been among the would-be rescuers. When working in
confined spaces, it is important that all workers remain alert and aware of their surroundings and familiarize
themselves with job site instructions and permits.
Prior to entering a confined space, the inspector should verify that it has been tested and cleared for entry
and that proper personal protective equipment is employed, including in some cases supplied-air respirators.
Detailed confined space entry training is always required before entering any confined space
Heat or Cold Exposure
Industrial coatings projects are often located in a range of temperatures from high heat to freezing cold. In
any hot environment, the human body has difficulty maintaining a core body temperature. When the heat
index rises above 103°F (39°C), there is a high risk for a range of heat-related illnesses such as heatstroke,
sunburn, and dehydration. The heat index is a single value that accounts for air temperature and humidity.
Working in direct sunlight can add up to 15 degrees to the heat index.
The greatest risk of cold-related injuries occurs when the body temperature drops below 95°F (35°C).
Windchill is the lowering of body temperature due to low-temperature airflow. It speeds up heat loss by
moving warm air away from the body. The lower the windchill, the colder it will feel outside and the greater
the risk of cold-related injuries such as hypothermia and frostbite.
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Hazardous Energy
Surface preparation and coating application
activities use tools that require an energized source
to operate. Energized refers to a state of being
electrically connected to or having a source of
voltage. Potential or stored energy can also present
a hazardous environment. This most commonly
occurs in pressurized systems when energy that is
confined is released unexpectedly. Power tools,
abrasive blasting, mixing (drills, agitators, etc.) and
spray applications all require a power source to operate and have the potential to store energy.
Anytime energized high pressure systems are present or being used on a worksite, they pose a serious
workplace hazard exposing workers to electric shock, electrocution, burns, fires, and explosions. Using
improperly installed equipment or damaged and/or ungrounded tools can result in electric shock or
electrocution. Any electrically operated inspection equipment used in hazardous environments, such as
confined spaces, should be intrinsically safe or not capable of causing an explosion.
Lock Out Tag Out (LOTO)
Lockout/Tagout or LOTO is the physical restraint of, all hazardous energy sources that supply power to a piece
of equipment, machinery, or system. LOTO is the process of isolating or disconnecting a system from its
energy source. The unexpected startup or release of stored energy while working on or near machinery or
equipment can result in serious injury or death to workers.
Even when a system is powered off, it may still contain residual or unused stored energy in the power supply.
Remember that just because something isn’t moving doesn’t mean that it doesn’t have the energy to power
up. When stored energy is released in an uncontrolled manner, individuals may be crushed or struck by
objects, moving machinery, equipment, or other items.
Working around energized systems can expose the inspector to the risk of electrical shock. To prevent this,
systems are locked out by blocking the flow of energy from the power source to the equipment with a padlock
or chain or by removing a component such as a fuse or a circuit breaker. Tags are then placed on each locking
device to identify the party locking out the power source. Before beginning work, inspectors must verify that
all energy sources have been de-energized. A locked-out system may have many locks, but there should only
be one lock and one key per person. For example, if the job requires three workers, then three locks should be
present. Locks can only be removed by the individual who installed them. Inspectors should maintain control
of their key for LOTO.
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Activity
Can you think of any other hazardous environments that an inspector may encounter on the
job?
23.4 Hazardous Activities and PPE
Hazardous Activities
Inspectors may work in the vicinity of hazardous
activities such as:
ƒ
Pre-cleaning (solvent use)
ƒ
Hand and power tool cleaning
ƒ
Abrasive blasting
ƒ
Mixing and thinning
ƒ
Spray application
Personal Protective Equipment (PPE) is essential for not only for the blaster and painter but also for
surrounding workers.
General PPE
ƒ
Safety glasses protect your eyes from dust, flying
debris, sparks, metal shavings, acids, or caustic
liquids or gasses
ƒ
Respirators are used to prevent the inhalation of
dust and other contaminants
ƒ
Gloves protect your hands from injury by sharp
or hot objects or harmful chemicals
ƒ
Safety boots protect your feet from slippery or
hot surfaces and heavy, rolling, or falling objects
ƒ
Hardhats protect your head from falling or overhead objects
ƒ
Ear protection is used in noisy areas to avoid hearing damage or loss
ƒ
Reflective clothing is used to make sure you are always highly visible
ƒ
Long sleeves and pants are used to protect your arms and legs from injury or harmful chemicals
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Abrasive Blasting and Waterjetting: Safety
Considerations
Abrasive blast cleaning and waterjetting are
dangerous operations that can cause harm to
people, equipment, and the environment. The high
pressure compressed air through the blasting
system combined with the air-propelled abrasive
from the nozzle can cause serious injury. The
process also releases dust and debris into the
atmosphere impacting the air quality. In addition,
loud noise from blast nozzles and compressors may also impede communication and cause hearing loss over
time.
High and ultra-high waterjetting may use pressures as high as 620 MPa (90,000 psi). Because of these high
pressures, the primary concern is with injuries that penetrate the skin and cause serious damage to the
tissues below. Also, like blasting, waterjetting may produce enough noise (up to 135 dBA) to create a hearing
hazard.
Important/Safety Warning
CAUTION! Comprehensive safety training is required to safely operate abrasive blast equipment
and waterjetting equipment. The information in this section only provides a high-level overview
of safety using these surface preparation methods.
Coating Application: Safety Considerations
Airless and plural component spray equipment
generate very high fluid pressure. Spray from the
gun, leaks, or ruptured components can inject fluid
through the skin and into your body, causing serious
injury, including the need for amputation. The
injection may look like a cut, but it is a very serious
injury, and medical treatment must be sought
immediately. The most common causes of injection
are placing your hand or body too close to the spray
tip or grabbing a leaking hose or fitting, even if you are wearing gloves or using a rag.
Explosion risks are another hazard due to the flammability of certain coating types that have low flashpoints.
Fire and/or explosion can occur if the sprayer is spraying or flushing flammable fluid in an area where air
circulation is poor and an open flame or spark is present. With an ungrounded spray system, the flow of fluid
through the sprayer and hose may create enough static electricity to cause a spark from the gun. That spark
can ignite flammable vapors.
Plural component spray units require an additional level of caution as the equipment utilizes electrical
elements as well as heat. High voltage electrical input is required to operate the heaters and heat traced spray
lines used to reduce the viscosity of high solids coatings. This creates the potential for workers to be exposed
to electrical shock due to improper grounding, set-up, or usage of the equipment. Today, many sprayers have
a ground connection area included in their design.
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Chapter 23: Safety Awareness
The biggest safety hazard when using conventional spray equipment is caused by solvent vapors. Because of
the relatively low air pressure required when using conventional air spray (30 to 50 psi average) compared to
airless spray, the applicator may have to thin the coating they are applying to make it sprayable. This amount
of thinning not only increases the Volatile Organic Content (VOCs) of the coating but increases workers’
exposure to higher concentrations of solvent vapor emissions. This creates a respiratory risk, and proper PPE
should be worn when working around spray operations.
23.5 Personal Responsibility
Every person on a job site has a personal
responsibility for their own safety, and well as a
responsibility to prevent accidents. Each of us is
expected to incorporate safety into every job
procedure. In addition, coating inspectors should:
ƒ
Know and obey all safety rules
ƒ
Obtain and read all safety-related documents
ƒ
Participate in all safety meetings
–
10
Discuss safety concerns/issues at the prejob
conference, at site meetings, or whenever
safety problems arise
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Chapter 23: Safety Awareness
ƒ
Attend any job or site-specific training required
ƒ
Always remain alert and aware of your surroundings
ƒ
Never perform a task that appears to be unsafe
ƒ
Wear the proper PPE and know how to maintain it
ƒ
Never use any chemicals unless you understand their toxic properties and how to use them safely
ƒ
Know to whom you are to report unsafe conditions, practice, and equipment to eliminate or reduce risks
ƒ
Know what to do in an emergency
–
Become familiar with the location of medical facilities, hazard warning systems, escape practices, rally
locations, etc.
Role of the Inspector
Unless observation of safety hazards is explicitly
within the inspector’s scope of services and the
inspector is qualified to perform the task, inspectors
should not routinely address matters involving the
safety and health of workers employed by others or
the public. However, an inspector who is aware of a
safety violation, no matter how slight, but does not
report it, may put themselves at risk of legal action if
an accident occurs. If an imminent safety hazard is
observed that is likely to cause injury or death to another worker, the inspector should take immediate action
to prevent the accident. Any safety hazards witnessed should be reported to the project supervisor for
resolution and documented in the daily log on a one-time basis. Beyond this, inspectors should obtain specific
guidance on their role relative to safety issues prior to the start of each project.
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Knowledge Checks
Answer the following questions. Answers can be found in the Answer Key in the Reference tab.
1. At what height is fall protection equipment required?
A. 6 feet (2 meters)
B. 3 feet (1 meter)
C. 12 feet (3.6 meters)
D. 9 feet ( 2.8 meters)
2. Who should an inspector obtain guidance from regarding their role relative to safety issues?
A. The asset owner
B. The contractor
C. Your employer
D. Your local safety administration
3. Which of the following should an inspector verify before entering a confined space?
(Select all that apply)
A. Verify the space has been tested and cleared for entry
B. Only intrinsically safe inspection equipment is used
C. Proper personal protective equipment is employed
D. That the workers have been properly trained
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Steel Panel Lab
Lab Overview
The Steel Panel Lab is designed to provide students with insight into the practicalities of installing a coating
system from the perspective of a craftworker (blasters/applicators) and the inspector. The core of this
practical lab will involve students preparing and coating a 12 x 12-inch steel panel. By performing the surface
preparation and coating application, students will be able to step into the shoes of the blasters and
applicators they will be working with in the field, providing greater insight into the day-to-day operations of a
coating project.
This coating lab also provides students with the opportunity to perform the role of an inspector within a
simulated real-world environment. At each stage of the surface preparation and coating process, students will
inspect their work using the equipment and processes explored in the previous labs. Students will then
document their inspection results within their Logbooks and later determine if the work they performed was
in conformance with the specification’s requirements.
The Steel Panel Lab can be broken down into three key stages:
1. Stage One: Pre-work
a. Students will prepare for the coating project by reviewing guidance documents, identifying inspection
requirements, and attending pre-job conferences and safety meetings.
2. Stage Two: Practical Lab
a. Students will perform the specified surface preparation and coating application.
b. Students will then inspect their work on the panel and document the results.
3. Stage Three: Verify Conformance
Students will use their inspection results and the ITP to determine if their work is in conformance with the
specification.
Learning Objectives
By the end of this lab, students should be able to:
1. Contribute to the planning and preparations for a coating project.
2. Describe the broad steps of the surface preparation and coating application processes.
3. Demonstrate the ability to use a wide range of inspection equipment to perform tests and measurements.
4. Utilize an ITP in the field to help determine when the work performed is in conformance with the
specification.
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CIP Level 1 Steel Panel Lab Specification
Table of Contents
1.
Section 1
Scope
Section 2
Codes, Standards and Definitions
Section 3
General Requirements
Section 4
Pre-Inspection
Section 5
Pre-Cleaning
Section 6
Pre-Treatment/Initial Preparation
Section 7
Surface Preparation
Section 8
Coating Materials
Section 9
Coating Application
Section 10
Colors
Section 11
Inspection and Test Plan
SCOPE OF SPECIFICATIONS
1.1
The item to be prepared and coated in accordance with this specification is:
•
2.
1’ x 1’ (30 cm2 ) steel panel, with an inverted “V” and a horizontal weld – prepare one
side of the panel only
CODES, STANDARDS, AND DEFINITIONS
2.1
All listed specifications and standards shall conform to the latest edition or revision
2.2
Local codes and standards having jurisdiction over materials, application and colors
shall apply
2.3
The following standard organizations are referenced:
2.4
•
American Society for Testing and Materials (ASTM International)
•
International Organization for Standards (IS0)
•
AMPP - formerly NACE International (NACE) and Society for Protective Coatings
(SSPC)
Testing and inspection of surfaces and coatings shall be completed utilizing individuals
being trained as NACE CIP Level 1 Coating Inspectors. The coating inspector shall be
responsible to the Owner represented by a NACE CIP Instructor.
AMPP CIP LEVEL 1
Panel Lab Specification
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2.5
Referenced Standards
2.5.1
SSPC–PA 1. “Shop, Field & Maintenance Painting”
2.5.2
SSPC–PA 2. “Procedure for Determining Conformance to Dry Film Thickness
Requirements”
2.5.3
SSPC – PA 3 - “A Guide to Safety in Paint Application”
2.5.4
SSPC – SP 1 - “Solvent Cleaning”
2.5.5
SSPC – SP 2 – “Hand Tool Cleaning”
2.5.6
SSPC – SP 3 – “Power Tool Cleaning”
2.5.7
NACE SP0188 – “Design, Fabrication, and Surface Finish Practices for Tanks &
Vessels to be Lined for Immersion Service”
2.5.8
NACE SP 0287 – Field Measurement of Surface Profile of Abrasive BlastCleaned Surfaces using a Replica Tape
2.5.9
NACE No. 2/SSPC SP-10 “Near White Metal Blast Cleaning”
2.5.10
NACE SP0178 – “Discontinuity (Holiday) Testing of New Protective Coatings on
Conductive Substrates”
2.5.11
ASTM D 4285 - “Standard Test Method for Indicating Oil or Water in
Compressed Air”
2.5.12
ASTM D 4417 - “Standard Test Methods for Field Measurement of Surface
Profile of Blast Cleaned Steel”
2.5.13
ASTM E337 – “Standard Test Method for Measuring Humidity with a
Psychrometer (the Measurement of Wet and Dry Bulb Temperatures)
2.5.14
ASTM D 7393 – “Standard Test Method for Indicating Oil in Abrasives”
2.5.15
ASTM C136/136M – “Standard Test Method for Sieve Analysis of Fine and
Coarse Aggregates”
2.5.16
ISO SA 2 ½ – “Very Thorough Blast Cleaning”
2.5.17
ISO 8502-3, Part 3 - “Assessment of Dust on Steel Surfaces Prepared for
Painting”
2.5.18
ISO 8503-2, Part 2 “Method for grading of surface profile of abrasive blastcleaned steel – Comparator procedure”
AMPP CIP LEVEL 1
Panel Lab Specification
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2.6
2.7
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Visual Guides
2.6.1
SSPC – Vis 1 – “Guide and Reference Photographs for Steel Surfaces Prepared
by Dry Abrasive Blast Cleaning”
2.6.2
SSPC – Vis 3 – “Guide and Reference Photographs for Steel Surface Prepared by
Hand and Power Tool Cleaning”
2.6.3
NACE SP 0188 – Visual Comparator
2.6.4
ISO 8501 - 2 – “Preparation of Steel Substrates Before Application of Paints and
Related Products”
Definitions
For the purposes of this specification, the following definitions shall apply:
2.7.1
Owner – AMPP
2.7.2
Owner’s Representative – Individual representing AMPP
2.7.3
Coating Manufacturer – Company that manufactured the specified coatings
and related products
2.7.4
Coating Manufacturer’s Representative - Individual representing the Coating
Manufacturer
2.7.5
Coating Inspector – Individuals authorized by the Owner to perform the coating
inspection for this project
2.7.6
Coating Applicator – Individuals authorized by the Owner to perform the work
defined in this specification
2.7.7
AMPP – NACE International (formerly National Association of Corrosion
Engineers) and SSPC – Society for Protective Coatings
2.7.8
CIP – Coating Inspector Program (NACE)/AMPP
2.7.9
SSPC – Now AMPP, formerly the Society for Protective Coatings
2.7.10
ISO – International Organization for Standardization
2.7.11
ASTM – American Society for Testing and Materials
2.7.12
Shall, Shall Not – A Mandatory Requirement
2.7.13
Should – Not Mandatory, however, represents a Strong Recommendation
2.7.14
May – An Optional Requirement
AMPP CIP LEVEL 1
Panel Lab Specification
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3.
GENERAL REQUIREMENTS
3.1
Coating application shall be in compliance with the requirements of SSPC – PA 1.
3.2
Coating application safety procedures shall meet the applicable federal, provincial,
municipal, and Owners’ requirements and in general compliance with SSPC –PA Guide 3.
3.3
In accordance with Work Place Hazardous Materials Identification System (WHMIS)
regulations, suitable labeling of paint and solvent containers, as well as Safety Data
Sheets (SDS) for all applicable products, must be provided. SDS for these products must
be made available on site.
3.4
The following shall not be painted:
•
4.
Backside of panel/bolt holes in panels
3.5
Welded attachments shall be stripe coated and finish coated.
3.6
Ambient conditions must meet the requirements of the Coating Manufacturer during
final surface preparation, coating application, and for the full duration of the cure cycle
for the specified coating. Ambient control equipment must be suitably configured so as
not to introduce contaminants or excess moisture into the work environment.
3.7
In the event of a conflict between these requirements and the Coating Manufacturers’
printed instructions, at the discretion of the Owner’s Representative, the more stringent
requirement will prevail.
3.8
Any deviations from this specification must be submitted in writing to the Owner’s
Representative.
PRE-INSPECTION
4.1
Prior to any work, the panel shall be inspected to confirm that the surface condition is
suitable to receive the specified pre-cleaning, pre-treatment, surface preparation, and
coating application.
4.2
At a minimum, the following conditions shall be documented for new work:
4.3
•
Rust Grade as per NACE/SSPC – Vis 1; or NACE/SSPC – Vis 3
•
Visible contaminants
•
General surface condition; noting any anomalies which may prevent successful
completion of the coating project.
Results of the pre-inspection shall be documented in the project Log Book.
AMPP CIP LEVEL 1
Panel Lab Specification
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5.
6.
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PRE-CLEANING
5.1
Prior to any other surface preparation, the panel shall be cleaned using a procedure
which is compliant with SSPC-SP-1.
5.2
All surfaces to be painted shall be tested for contamination by chlorides using a Brestle
Patch or by a sleeve test in accordance with ISO 8502-6 and ISO 8502-9. Concentrations
shall be measured either with a Conductivity Meter or a Kitagawa Tube. Chloride
contamination shall not exceed 30 parts per million (PPM) or 30 micro siemens per sq
centimeter.
5.3
If the panel becomes contaminated after application of the first coat, the surface shall
be cleaned in accordance with the Coating Manufacturers written instructions prior to
application of the topcoat.
PRE-TREATMENT/INITIAL PREPARATION
6.1
Following pre-cleaning and prior to abrasive blasting, the panel shall be prepared in
accordance with the requirements of SSPC SP 1, SSPC SP 2, and/or SSPC SP 3.
6.2
Prior to abrasive blasting, all sharp projections and weld spatter shall be ground to
produce a smooth contour. Prior to abrasive blasting, all welds shall conform to the
visual appearance of Butt Weld Condition D as per the visual comparator
complimenting NACE SP0188.
6.3
Prior to abrasive blasting, all sharp edges of new steel surfaces (excepting the outer
edges and bolt holes) shall be ground to a smooth radius of 3 mm (1/8”).
6.4
Prior to abrasive blasting, the panel shall be inspected and evaluated in accordance with
SSPC SP1, SP 2, and SP 3 and NACE SP 0188.
SURFACE PREPARATION
7.1
As a supplement to these written standards, visual guides as produced by NACE, SSPC,
and ISO can be used to assist in the evaluate the surface preparation. In the event of a
conflict between assessment using a visual guide and the applicable written standard,
the written standard shall prevail
7.2
All pneumatic equipment used for surface preparation shall utilize clean, oil and
moisture free air as confirmed by ASTM D 4285, “Standard Test Method for Indicating
Oil or Water in Compressed Air”
7.3
The Owner’s Representative shall provide a copy of the abrasive supplier’s sieve analysis
which shall be reviewed by the Inspector.
AMPP CIP LEVEL 1
Panel Lab Specification
8
Sheet 5 of 11
For Classroom Use Only
Date of Issue: February 2022
© NACE International
Chapter 22: Holiday Detection
7.4
Abrasive cleanliness shall be confirmed in accordance with ASTM D 7393.
7.5
Final surface preparation will meet the requirements of NACE No. 2/SSPC – SP 10 (North
America) or ISO 2 ½ (Rest of the World). In the event that the specified level of surface
cleanliness conflicts with the information provided by the Coating Manufacturer
Product Data Sheet, the more stringent standard will apply at the discretion of the
Owner’s Representative.
7.6
Unless otherwise specified by the Owner’s Representative, the abrasive must produce a
sharp angular surface profile of the depth specified as 38µ -76µ (1.5mils – 3mils).
Surface profile will be measured in accordance with ASTM D 4417, Method B or C, or
- ISO – 8503-2 (Medium/Coarse).
7.7
Ambient control equipment must be suitably configured so as not to introduce
contaminants or excess moisture into the work environment
7.8
After abrasive blasting, the panel must be cleaned of dust and particulate, thereby
conforming to ISO 8502 – 3, Part 3, Dust size - Class 3.
7.9
Immediately prior to coating application, surfaces must be free of all visible
contaminants.
7.10 The blasted surface shall be coated prior to the development of rust bloom.
7.11 Regardless of the initial condition of the substrate, surface preparation method, or
coating being applied, the surface to be coated shall meet the specified surface
preparation standard for the applicable Coating Standard and the Coating
Manufacturers’ requirements immediately prior to application of the first coat.
8.
COATING MATERIALS
8.1
Acceptable coating materials are those identified by the Owner’s Representative.
8.2
All coating materials shall be produced by the same Coating Manufacturer.
8.3
Only thinners specified in the Coating Manufacturers’ written instructions shall be used
within the recommended limits of the Coating Manufacturer.
8.4
All coating materials shall be prepared for use in strict accordance with all the
requirements of the Coating Manufacturers’ latest written instructions. Only full kits can
be mixed.
AMPP CIP LEVEL 1
Panel Lab Specification
Sheet 6 of 11
For Classroom Use Only
Date of Issue: February 2022
9
CIP Level 1
Chapter 22: Holiday Detection
8.5
Coating materials shall be delivered to the job site premixed by the manufacturer to the
color specified by the Owner’s Representative. Material shall be delivered in the original,
sealed, and undamaged containers bearing the manufacturer’s name, brand
identification, and batch numbers. All coating materials used shall be within the shelf
life identified by the Coating Manufacturer. All coating materials of the same generic
type and color shall be identified with the same batch number unless otherwise
approved by the Owners’ Representative.
8.6
All coating materials shall be stored in a clean, dry, well-ventilated area, protected from
sparks, flame, direct rays of the sun, and heat or cold. Acceptable storage conditions
shall be provided in accordance with the written instructions provided by the Coating
Manufacturer.
8.7
As soon as possible, after arrival at the job-site, the coating materials and additives shall
be inspected to determine if they meet the specified requirements. Any out-of-date or
otherwise non-compliant materials shall be replaced in a timely way so as not to impact
the scheduled completion of the work.
8.8
Converters, thinners, and other additives shall be from the same manufacturer as the
coating and used only in accordance with the Coating Manufacturers’ latest written
instructions.
8.9
Before application, all materials shall be mechanically agitated until the ingredients are
completely mixed in accordance with the Coating Manufacturers’ latest written
instructions. Mixing equipment shall meet the Coating Manufacturers’ requirements.
8.10 The mixing operation is subject to inspection to determine if the mixing operation
meets the specified requirements.
8.11 If required by the Coating Manufacturer, materials which have a tendency to settle
rapidly shall be continuously agitated during application.
8.12 No materials for which the Coating Manufacturers’ stated pot life has been exceeded
may be applied or mixed into a new batch.
8.13 Material shall not be prepared for use when the ambient temperature, the surface
temperature, material temperature, relative humidity, or dew point is below or above
that specifically permitted in the Coating Manufacturers’ latest printed Product Data
Sheet.
9.
COATING APPLICATION
9.1
General Coating Application Requirements
AMPP CIP LEVEL 1
Panel Lab Specification
10
Sheet 7 of 11
For Classroom Use Only
Date of Issue: February 2022
© NACE International
Chapter 22: Holiday Detection
9.1.1
Coatings shall only be applied to thoroughly prepared surfaces as defined by
these Specifications. Ambient conditions must meet the Coating
Manufacturer’s latest printed instructions prior to application, during, and
throughout the cure cycle of the coatings. If required, humidification,
dehumidification, and/or temperature controls shall be used to meet this
requirement.
9.1.2
Immediately prior to coating application and periodically throughout the
coating application, ambient conditions are subject to inspection to determine
if they meet the requirements of these Specifications. Coating application shall
not proceed unless the required ambient conditions are present.
9.1.3
Coatings shall be applied in strict accordance with the Coating Manufacturers’
latest written Product Data Sheet or written recommendation. In particular, the
induction times, pot life times, minimum and maximum recoat times,
minimum and maximum material, substrate, and ambient temperatures as
stated in the Coating Manufacturers Product Data Sheet (latest printed version)
shall be strictly adhered to.
9.1.4
All materials shall be applied in a workmanlike manner in accordance with
SSPC-PA 1 and the Coating Manufactures’ latest printed Product Data Sheet to
achieve the required dry film thickness.
9.1.5
Application by brush, roller, or spray shall be in accordance with the Coating
Manufacturers’ Product Data Sheet (PDS), latest printed version. Generally,
coatings shall be spray applied; however, brush and roller application may be
required to access areas inaccessible to spray application or under certain
circumstances where brush & roller application is more applicable to the work
at hand.
9.1.6
Inherent overspray from zinc coatings will be tolerated providing any
overspray is removed prior to overcoating.
9.1.7
Alternate coats of paint shall be distinguished from one another by different
colors, with the exception of the stripe coat and topcoat.
9.1.8
Application of successive coats shall be completed within the minimum and
maximum recoat windows specified by the Coating Manufacturer. If the recoat
window is exceeded, the coating shall be removed and replaced or adequately
abraded prior to application of the next coat at the discretion of the Owner’s
Representative.
9.1.9
Prior to application of the topcoat, weld lines, corners, edges (with the
exception of outer edges of the plate), and other areas difficult to spray shall
receive an initial stripe coat by brush to ensure adequate film build. Inorganic
zinc coatings shall be used for stripe coating.
AMPP CIP LEVEL 1
Panel Lab Specification
Sheet 8 of 11
For Classroom Use Only
Date of Issue: February 2022
11
CIP Level 1
9.2
Chapter 22: Holiday Detection
9.1.10
Unless otherwise specified by the Coating Manufacturer, all coatings applied
by spray shall be applied in even, parallel passes overlapping each pass by 50%
immediately followed by cross spray passes to achieve a smooth, uniform
appearing, continuous film that is free of visual defects.
9.1.11
Defects include but are not limited to; bare spots, holidays, pinholes, runs,
sags, blisters, dry spray, blushing, crazing, cracking, fish-eyes, bubbling, or
other blemishes.
9.1.12
Coating application is subject to inspection both during the application and
after initial cure. If required, coating remediation/repair procedures shall be
according to the Coating Manufacturers’ recommendations.
9.1.13
The coating shall be applied at the dry film thickness range specified in the
Coating Manufacturer’s product data sheets. When measured in accordance
with the Restriction Level 3 of SSPC PA 2, the dry film thickness of the primer
and the total system must fall within the specified range of dry film thickness.
9.1.14
Each applied coat is subject to inspection after the initial cure of the coat and
prior to application of succeeding coats. Any remediation/repair procedures
required will be completed prior to application of succeeding coats.
9.1.15
The minimum curing time shall be observed as specified by the Coating
Manufacturer before handling or allowing the coated surface to go into service.
9.1.16
The panel is subject to a final inspection to determine if all of the specification
requirements have been met. All deficiencies noted in the final inspection will
be corrected to the satisfaction of the Owners’ Representative prior to return
to service.
Coating Tests And Inspection
9.2.1
The Coating Inspector shall be responsible to the Owner’s Representative.
9.2.2
The Coating Inspector shall observe, report and document all work required by
this specification.
9.2.3
The Coating Inspector is not granted the authority to stop the work except if
observing a significant safety violation that is deemed to be an immediate
danger to the life and health of those involved in this work.
9.2.4
The Coating Inspectors’ duties and functions will be carried out in accordance
with the guidelines and ethical standards of the NACE CIP.
AMPP CIP LEVEL 1
Panel Lab Specification
12
Sheet 9 of 11
For Classroom Use Only
Date of Issue: February 2022
© NACE International
Chapter 22: Holiday Detection
9.3
9.2.5
The Coating Inspector will keep complete written records of all tests,
observations, and measurements taken and will record all occurrences which
could have an effect on the quality and integrity of surface preparation and
applied coatings.
9.2.6
The Coating Inspector shall record all inspection activities in the dated project
logbook. The logbook shall be submitted to the Owner’s Representative on the
final day of the CIP class.
9.2.7
The Coating Inspector shall perform a pre-inspection of the surfaces to be
coated.
9.2.8
The Coating Inspector shall perform inspections of the pre-cleaning, pretreatment, initial and final surface preparation prior to coating application.
9.2.9
The Coating Inspector shall inspect the coating materials prior to coating
application.
9.2.10
The Coating Inspector shall inspect the mixing and thinning of all coatings prior
to application.
9.2.11
The Coating Inspector shall inspect the coating application in progress
including, monitoring the wet film thickness (topcoat only).
9.2.12
The Coating Inspector shall inspect each applied coat prior to application of the
succeeding coat for any visible defects and dry film thickness. When repairs are
necessary, they shall be inspected prior to application of the succeeding coat.
9.2.13
The Coating Inspector shall inspect the finished coated surfaces for dry film
thickness and visible coating defects. Dry film thickness measurements will be
evaluated in accordance with SSPC – PA 2, Restriction Level 3.
9.2.14
The Coating Inspector shall perform holiday testing according to NACE SP0188.
Coating Repairs
9.3.1
At the discretion of the Owner’s Representative, defective coatings shall be
accepted as is touched up or removed and replaced.
9.3.2
Whenever touch-up is specified prior to a succeeding coating of paint, it shall
include omissions, welds, burns, rusted areas, and all damaged or defective
paint. The touched-up surface shall be cleaned before painting using surface
preparation methods at least as effective as those specified for the original
coating.
9.3.3
Touch-up shall be done with procedures and materials that will produce a
coating better than or equal to the original coating specification.
AMPP CIP LEVEL 1
Panel Lab Specification
Sheet 10 of 11
For Classroom Use Only
Date of Issue: February 2022
13
CIP Level 1
10.
Chapter 22: Holiday Detection
COLORS
10.1 Color selection for all surfaces will be at the discretion of the Owner’s Representative.
11.
INSPECTION AND TEST PLAN (ITP)
11.1 The ITP shall guide the Inspector in the performance of the inspection activities.
11.2 The Inspector is responsible for reviewing the ITP to ensure its applicability for the work
and to report any errors, omissions, or ambiguities to the Owner’s Representative
during the pre-job conference.
AMPP CIP LEVEL 1
Panel Lab Specification
14
Sheet 11 of 11
For Classroom Use Only
Date of Issue: February 2022
© NACE International
Item
Activity
Inspection Method
or Equipment
Standard
1
Initial Condition
Visual Inspection
SSPC VIS 1 or
SSPC VIS 3
2
Pre-Cleaning
Visual Inspection
SSPC-SP 1
3
Initial Preparation (Hand &
power tool cleaning)
SSPC–VIS 3
4
Blast Media
Chloride Testing
5
Pre-Treatment (Welds)
Visual Comparator
Conformance
Criteria
Results (C=conformance
NC= Non-conformance
or N/A)
Specification
Reference
N/A
4.1
No visible oil or
grease
5.1
All material removed
6.1
ISO 8502-6,
IS0 8502-9
30 PPM or 30 micro
siemens
5.2
NACE SP0178
Sharp edges ground
to a smooth radius
of 3mm/ (1/8”)
6.2 - 6.3
7.4
SSPC-SP 2 and
SSPC-SP 3
Blast Media Cleanliness
Vial Test
ASTM D7393
7
Compressed air cleanliness
Blotter Test
ASTM D4285
No visible
contamination
7.2
8
Blast Cleanliness
(North America)
SSPC–VIS 1
NACE No. 2/
SSPC SP-10
Up to 5% staining
allowed
7.5
9
Blast Cleanliness
(Rest of World)
ISO 8501-1
ISO Sa 2 ½
Trace contaminates
shall show as slight
stains in the form of
7.5
spots or stripes
10
Surface Profile
Digital Profile
Gauge
ASTM D4417,
Method B
38µm -76µm (1.5mils
– 3mils)
7.6
15
Chapter 22: Holiday Detection
6
No visually
detectable oil film on
surface of water
Activity
11
Residual Dust
12a
Coating Materials – Batch
number: Primer: Part A
Inspection Method
or Equipment
Standard
Dust Tape Test
ISO 8502-3
Product Data Sheet
N/A
Conformance
Criteria
Dust size, Class 3
Batch numbers
Primer Part A:
Results (C=conformance
NC= Non-conformance
or N/A)
Specification
Reference
7.8
8.5 – 8.8 and
10.1
© NACE International
Chapter 22: Holiday Detection
Item
_____________________
12b
Coating Materials – Batch
number: Primer: Part B
Product Data Sheet
N/A
Batch numbers
Primer Part B:
8.5 – 8.8 and
10.1
_____________________
Batch numbers
12c
Coating Materials – Batch
number: Topcoat: Part A
Product Data Sheet
N/A
Topcoat Part A:
8.5 – 8.8 and
10.1
_____________________
Batch numbers
12d
Coating Materials – Batch
number: Topcoat: Part B
Product Data Sheet
N/A
Topcoat Part B:
8.5 – 8.8 and
10.1
_____________________
CIP Level 1
12f
12g
As per the PDS:
Coating Materials – Shelf Life:
Product Data Sheet
Primer: Part A
N/A
Coating Materials – Shelf Life:
Product Data Sheet
Primer: Part B
N/A
Coating Materials – Shelf Life:
Product Data Sheet
Topcoat: Part A
N/A
_____________________
As per the PDS:
____________________
As per the PDS:
_____________________
8.5 – 8.8 and
10.1
8.5 – 8.8 and
10.1
8.5 – 8.8 and
10.1
16
12e
Item
12h
13a
13b
Activity
Inspection Method
or Equipment
Coating Materials – Shelf Life:
Product Data Sheet
Topcoat: Part B
Ambient Conditions – Mixing
and Thinning
(Primer Coat)
Digital Dew Point
Meter or Sling
Psychrometer and
Magnetic Surface
Temperature
Gauge
Mixing and Thinning – Primer
Product Data Sheet
Method/Equipment
Standard
Conformance
Criteria
As per the PDS:
N/A
_____________________
N/A
As per the
Specification or PDS:
Results (C=conformance
NC= Non-conformance
or N/A)
Specification
Reference
8.5 – 8.8 and
10.1
8.13
_____________________
N/A
As per the
Specification or PDS:
8.9 and 8.11
_____________________
13c
15
Ambient Conditions – Prior
to Primer Application
Primer Application Workmanship
Digital Dew Point
Meter or Sling
Psychrometer and
Magnetic Surface
Temperature
Gauge
Visual Inspection
As per the PDS:
N/A
8.12
_____________________
N/A
As per the
Specification or PDS
(as applicable):
9.1.1 and 9.1.2
_____________________
SSPC-PA 1
As per the
Specification or PDS
(as applicable):
_____________________
9.1.4, 9.1.8 and
9.1.10
17
Chapter 22: Holiday Detection
14
Mixing and Thinning – Primer
Timer
Pot Life
16
17
18
Activity
Stripe Coat
Inspection Method
or Equipment
Visual Inspection
Primer Cure – Dry to topcoat
Solvent Sensitivity
Test
Dry Film Thickness – Primer
Type I Analog or
Type II Digital
Gauge
Standard
Conformance
Criteria
N/A
All edges, welds, bolt
holes, and areas
difficult to spray
As per the pre-job
ASTM D4752 or conference and
ASTM D5402
applicable standard
PASS/FAIL
SSPC-PA 2
As per the
Specification or PDS
(as applicable):
Results (C=conformance
NC= Non-conformance
or N/A)
Specification
Reference
9.1.9
© NACE International
Chapter 22: Holiday Detection
Item
9.1.15
9.1.13
_____________________
CIP Level 1
19b
19c
Mixing and thinning –
Topcoat Mixing Method/
Equipment
Mixing and Thinning –
Topcoat Pot Life
Product Data Sheet
As per the
N/A
Specification or PDS:
8.13
_____________________
N/A
As per the
Specification or PDS:
8.9 and 8.11
_____________________
Timer
N/A
As per the
Specification or PDS:
8.12
_____________________
18
19a
Ambient Conditions – Mixing
and Thinning (Topcoat)
Digital Dew Point
Meter or Sling
Psychrometer and
Magnetic Surface
Temperature
Gauge
Item
20
21
Activity
Ambient Conditions – Prior
to Topcoat Application
Topcoat Application –
Workmanship
Inspection Method
or Equipment
Digital Dew Point
Meter or Sling
Psychrometer and
Magnetic Surface
Temperature
Gauge
Visual Inspection
Standard
N/A
Conformance
Criteria
As per the
Specification or PDS
(as applicable):
Results (C=conformance
NC= Non-conformance
or N/A)
Specification
Reference
9.1.1 and 9.1.2
_____________________
SSPC-PA 1
As per the
specification/PDS
and/or PA-1
9.1.4 and
9.1.10
_____________________
22
Topcoat – Final cure
Visual Inspection
N/A
As per the
Specification or PDS:
9.1.14
_____________________
23
25
26
Visual Inspection
Total Dry Film Thickness
Type I Analog or
Type II Digital
Gauge
SSPC-PA 2
Holiday Detector
NACE SP0188
Holiday Inspection
Coating Repairs/Touch Up
Visual Inspection
N/A
No visual defects
As per the
Specification or PDS:
9.1.11
9.1.13
_____________________
N/A
No holidays
As per the
Specification or PDS:
_____________________
9.1.11
9.1.12 and 9.3
19
Chapter 22: Holiday Detection
24
Final Visual Inspection
CIP Level 1
20
Chapter 22: Holiday Detection
© NACE International
Chapter 7: Pre-Cleaning
Answer Key
Chapter 16: Inspection Test Plans
Practical Lab/Self-Study
Activity 1
Inspection Test Plan (Coating Application)
No.
Activity
7.1
Inspect the precleaned surface
7.2
Observe the stripe
coating by roller
7.3
Monitor the
environmental
conditions
7.4
Inspect roller and
brush application
(if applicable)
7.5
Measure the wet
film thickness
7.6
Inspection
Equipment
Visual inspection
Visual
inspection
Inconsistency
Brush not roller
Controlling
Documents
Acceptance Criteria
Specification
Free of visible
contaminants
All areas
Specification
All welds, nuts, bolts,
Omission
edges, and corners
Air Temperature
stripe coated
All areas
Surface Temp: 35°F 49°C
Inconsistency
°F and °C mixed
Digital all-in-one
device or a
thermometer &
hygrometer
PDS
Frequency
Surface Temp at least
Inconsistency
5°F above dew point
Every 3 hours, not just at
the start of each shift
Humidity < 85%
At the beginning of
each shift
High-quality finish
achieved
Areas coated by
brush or roller
(excluding
stripping)
175 μm - 338 μm
One per section or
as needed
Omission
Inspect the coating
Visual inspection
Specification
Measuring DFT
film
Coating film is free
from visible defects
and debris
All areas
7.7
Monitor the recoat
window
8 hours minimum
Each layer, all
areas
7.8
Perform holiday
testing
Ambiguity
What defines “high-quality”
Visual inspection
Specification
Inconsistency
Comb
Gauge responsibility
PDS
Contractor’s
—
Low-voltage wet
sponge Chalk
PDS
No holidays. Identified
Ambiguity
NACE SP0188 holidays to be marked All areas
No temperature is listed in the specification
and reported
CIP Level 1
Chapter 7: Pre-Cleaning
Activity 2
5. Pre-treatment
No.
Activity
Inspection
Equipment
Controlling
Documents
Acceptance Criteria
5.1
Inspect the precleaned surface
Visual inspection
Specification
Sharp edges rounded and weld defects
ground smooth & edges raised to 45°
5.2
Inspect the precleaning
Visual inspection
SSPC-SP 1
All oil, grease, and other visible
contamination removed
6. Surface Preparation
6.1
Verify conditions are
suitable for blasting
Visual inspection
Specification
No adjacent coating operations or wet
(coated) surfaces
6.2
Test abrasive
cleanliness
Visual inspection
Vial Test
Specification
Media is clean, dry, and free from foreign
matter
6.3
Very abrasive type
Visual inspection
Specification
Media is steel grit or garnet
6.4
Test the cleanliness
of compressed air
Absorbent or
non-absorbent
collector
ASTM D4285
No indication of water or oil discoloration
present
6.5
Inspect the postblast clean-up
Visual inspection
Specification
No spent abrasive or dust on the surface
6.6
Assess surface
cleanliness
Visual inspection
SSPC-VIS 1
NACE No.2 /
SSPC-SP 10
–
–
–
6.7
Measure the surface
profile
Replica Tape
Micrometer
ASTM D4417
Method C
Surface profile:
– 75 - 100 μm
– Angular
6.8
Post-blast inspection Visual inspection
Specification
Prepared surface has no visible defects
6.9
Inspect the surface
for deterioration
Visual inspection
Specification
The surface has no patches of black or
brown discoloration within an hour of
blasting
6.10
Measure chloride
contamination (if
required by 6.9)
Bresle Patch Kit
Conductivity Meter
ISO 8502
Part 6 & 9
< 62 µS/cm (< 40 ppm)
No visible contaminants
No loose or tightly adherent material
Up to 5% staining
© NACE International
Chapter 7: Pre-Cleaning
Chapter 17: Practical Math
Knowledge Checks
1.
Measurement
Total
Average
Complies
Area
Reading 1
Reading 2
Reading 3
(1+2+3)
(Total ÷ No. of
Measurements)
(Yes/No)
A
10 mils
12 mils
12 mils
34
11.3
Yes
B
12 mils
14 mils
13 mils
39
13.0
Yes
C
15 mils
14 mils
14 mils
43
14.3
Yes
D
14 mils
13 mils
10 mils
37
12.3
Yes
E
12 mils
13 mils
11 mils
36
12.0
Yes
12.58
Yes
Overall Average
SSPS-PA 2 Level 3 Calculations
ƒ
Specified Range: 12-15 mils
ƒ
80% of 12 mils:
12 x 0.8 = 9.6 mils
ƒ
120% of 15 mils:
15 x 1.20 = 18 mils
Any single spot measurement must be greater than 9.6 mils
and less than 18 mils.
2.
Imperial
Metric
Step 1: Calculate TE
= 100% - % loss (decimal)
= 1 - .10 = .90
Step 1: Calculate TE
= 100% - % loss (decimal)
= 1 - .10 = .90
Step 2: Calculate Practical Coverage
= 1,604 x SBV x TE ÷ DFT
= 1,604 x .45 x .90 ÷ 5
= 129.92 (rounded to 130 ft2 / gal)
Step 2: Calculate Practical Coverage
= 1,000 x SBV x TE ÷ DFT
= 1,000 x .45 x .90 ÷ 127
= 3.18 m2 / l (rounded to 3 m2/l)
Step 3: Calculate Material Consumption
= Area ÷ Practical Coverage
= 5,000 ÷ 130
= 38.45 (rounded to 39 gal)
Step 3: Calculate Material Consumption
= Area ÷ Practical Coverage
= 500 ÷ 3
= 166.66 (rounded to 167 liters)
CIP Level 1
Chapter 7: Pre-Cleaning
Self-Study
1.
Solvent
Solvent by
volume 15%
Solids
Solids by
volume 85%
Solvent
Solids
0.85 SBV
Solvent
Solvent by
volume 30%
Solids
Solids by
volume 70%
0.70 SBV
Solvent by
volume 45%
Solids by
volume 55%
0.55 SBV
Solvent
Solids
Solvent by
volume 65%
Solids by
volume 35%
0.35 SBV
2. 2.7 – 5.3 mils (68-136 microns) WFT
Calculation:
1. 51 (2 mils ) ÷ 0.75 SBV = 68 microns (2.7 mils) WFT minimum
2. 102 (4 mils ) ÷ 0.75 SBV = 136 microns (5.3 mils) WFT maximum
© NACE International
Chapter 7: Pre-Cleaning
3.
Minimum DFT
Maximum DFT
Step 1 Multiply minimum DFT by minimum
tolerance:
150 x .80 = 120 µm
Step 1 Multiply minimum DFT by minimum
tolerance:
200 x 1.50 = 300 µm
Step 2 Calculate the Sum:
140 + 135 + 157 = 432
Step 2 Calculate the Sum:
220 + 190 + 210 = 620
Step 3 Divide the Sum by the number of values in
the set:
432 ÷ 3 = 144 µm
Step 3 Divide the Sum by the number of values in
the set:
620 ÷ 3 = 206.6 µm
144 µm ≥ 120 µm – within tolerance limits
206.6 µm ≤ 300 µm – within tolerance limits
4.
Imperial
Metric
Step 1: Calculate the Adjusted SBV
Adjusted SBV = SBV ÷ 1 + Thinner %
= 0.70 ÷ 1.15
= 0.608 (rounded to 0.61)
Step 1: Calculate the Adjusted SBV
Adjusted SBV = SBV ÷ 1 + Thinner %
= 0.70 ÷ 1.15
= 0.608 (rounded to 0.61)
Step 2: Calculate the WFT
WFT = DFT ÷ Adjusted SBV
= 9 ÷ 0.61
= 14.75 mils
Step 2: Calculate the WFT
WFT = DFT ÷ Adjusted SBV
= 229 ÷ 0.61
= 375.40 µm
CIP Level 1
Chapter 7: Pre-Cleaning
5.
Imperial
Metric
Step 1: Calculate the Adjusted SBV
Adjusted SBV = SBV ÷ 1 + Thinner %
= 0.75 ÷ 1.125
= 0.666 (rounded to 0.67)
Step 1: Calculate the Adjusted SBV
Adjusted SBV = SBV ÷ 1 + Thinner %
= 0.75 ÷ 1.125
= 0.666 (rounded to 0.67)
Step 2: Calculate minimum DFT
WFT = DFT ÷ Adjusted SBV
= 2 mils ÷ 0.67
= 2.98 mils
Step 2: Calculate minimum DFT
WFT = DFT ÷ Adjusted SBV
= 51 µm ÷ 0.67
= 76.11 µm
Step 3: Calculate maximum DFT
WFT = DFT ÷ Adjusted SBV
= 4 mils ÷ 0.67
= 5.97 mils
Step 3: Calculate maximum DFT
WFT = DFT ÷ Adjusted SBV
= 102 µm ÷ 0.67
= 152.23 µm
Therefore, the applicator should strive to apply the coating within a range of 3 - 6 mils (76 - 152 microns) WFT.
Even with the addition of 12.5% thinner, the coating should “shrink” to 2 - 4 mils (51 - 102 microns) DFT.
6.
Imperial
7.
Metric
Step 1: Calculate TE
= 100% - % loss (decimal)
= 1 - .10 = .90
Step 1: Calculate TE
= 100% - % loss (decimal)
= 1 - .10 = .90
Step 2: Calculate Practical Coverage
= 1,604 x SBV x TE ÷ DFT
= 1,604 x .45 x .90 ÷ 5
= 129.92 (rounded to 130 ft2 / gal)
Step 2: Calculate Practical Coverage
= 1,000 x SBV x TE ÷ DFT
= 1,000 x .45 x .90 ÷ 127
= 3.18 m2 / l (rounded to 3 m2/l)
Step 3: Calculate Material Consumption
= Area ÷ Practical Coverage
= 5,000 ÷ 130
= 38.45 (rounded to 39 gal)
Step 3: Calculate Material Consumption
= Area ÷ Practical Coverage
= 500 ÷ 3
= 166.66 (rounded to 167 liters)
= 1,604 sq. ft x SBV ÷ DFT
= 1,604 x 0.65 ÷ 1
= 1,042 sq. ft
= 1000 m2 x SBV ÷ DFT
= 1000 x 0.75 ÷ 220
= 3.4 m2
= 1000 m2 x SBV ÷ DFT
= 1000 x 0.35 ÷ 80
= 4.375 m2
= 1,604 sq. ft x SBV ÷ DFT
= 1,604 x 0.40 ÷ 4
= 106.4 sq. ft
© NACE International
Chapter 7: Pre-Cleaning
8. Step 1: Calculate TE
= 100% - % loss (decimal)
= 1 - .20 = .80
Step 3: Calculate Material Consumption
= Area ÷ Practical Coverage
= 2323 ÷ 7
= 331.85 liters
Step 2: Calculate Practical Coverage
= 1000 x SBV x TE ÷ DFT
= 1000 x .75 x .80 ÷ 85
= 7.05 liters
Chapter 18: Measuring Environmental Conditions
Knowledge Checks
1. A. Verify calibration of both instruments
2. C. At the actual work location
D. At areas that are likely to be hotter or colder than the normal
3. B. Dew point
Self-Study
1. Possible answers:
Not allowing the meter to acclimatize when moving between starkly different environments
Obstructing air flow to the meter by having your hand or fingers near the sensor (body heat can cause
inaccurate readings)
Dragging the meter between surface temperature readings
Using too much or too little pressure between the meter and surface
Dirty or contaminated sensors
Not allowing readings to stabilize before recording the measurement
2. C. Distilled water
3. Steps:
1. Saturate the wick with clean water
2. Whirl at a moderate speed for ~20-30 seconds
3. Read the wet-bulb temperature
4. Repeat Steps 2 & 3 until the wet-bulb temperature stabilizes
5. Record the temperature from the wet-bulb and dry-bulb thermometer
6. Calculate the wet-bulb depression by subtracting the wet-bulb temperature from the dry-bulb
temperature
CIP Level 1
Chapter 7: Pre-Cleaning
7. Determine relative humidity and dew point by referencing a psychrometric table or a dewpoint
calculator
8. Record the relative humidity and dewpoint temperature
Chapter 19: Soluble Salt Detection
Knowledge Checks
1. C. Potassium Ferricyanide Test
3. A. Four times
2. B. White
4. D. Ion Test Strips
Self-Study
1. Chlorides
Sulfates
Nitrates
2. Limits to be accepted
Test method to be used
Locations in which tests should
be administered
Specific salts to be limited
Frequency of testing
3. Bresle Patch
Soluble Salt Meters
Sleeve Test
Conductivity Meters
Chapter 20: Measuring Surface Profile
Knowledge Checks
1. D. As a range of measurements
2. A. Dust on the surface
B. Using an incorrect grade of tape
C. Not accounting for the thickness of the mylar tape
D. Under burnishing the mylar tape
3. C. Take 10 readings per location, record the maximum value, then determine the average for all maximum
values as the reported profile
D. Take 10 readings and record the average of those ten (10) readings as the reported profile depth
© NACE International
Chapter 7: Pre-Cleaning
Self-Study
1. ISO Comparator
2. Finer-than-Fine Grade
Replica Tape
Fine Grade
Digital Profile Gauge
Medium Grade
Coarse Grade
3. Coarse for 20 to 64 µm (0.8 to
2.5 mils)
X-Coarse for 38 to 115 µm (1.5
to 4.5 mils)
Coarser-than-Coarse Grade
4. ASTM D 4417 Method C
NACE SP 0287-2002
5. Variation in point-to-point profile over the surface being tested
The presence of particles of dirt on either the replica tape or gauge
Gauge accuracy
The rubbing or burnishing technique
Chapter 21: Measuring Film Thickness
Knowledge Checks
1. D. The last tooth that has coating on it
4. A. Selecting reference coated standards below
and above the anticipated coating thickness
2. A. It is intrinsically safe
5. B. Three (3)
3. B. 2.5 cm (1 inch)
6. D. Fifteen (15)
Self-Study
1. SSPC-SP 2 - 5 spot measurements (3 measurements per spot)
ISO 19840 - Minimum 10 measurements
CIP Level 1
Chapter 7: Pre-Cleaning
2.
Bonus: ‘R’ refers to a repeat measurement. Gauge Reading 3 was not repeated as the Sampling Plan within ISO
19840 only allows two reads to be repeated for a measurement area of this size.
3. SSPC-SP 2 - 48 μm - 96 μm
ISO 19840 - 48 μm - 80 μm
4a. Yes.
Yes. The average of each spot is between 48 μm - 96 μm
Yes. Specified DFT = 60 - 80 μm; Measured DFT = 70 μm
4b. No.
Yes. Minimum DFT = 60 μm; average = 71 μm
Yes. 80% of Minimum DFT = 48 μm;Lowest Reading = 58 μm
Yes. 10% of readings are between 48 - 60 μm
No. Gauge Reading 9 = 81 μm; Gauge Reading 10 = 84 μm
Chapter 22: Holiday Detection
Knowledge Checks
1. B. Visually, you cannot use a holiday detector
2. A. Telegraphing
© NACE International
Chapter 7: Pre-Cleaning
Self-Study
1. Low Voltage DC
High Voltage DC (Pulse DC, Continuous, and Constant DC high voltage detectors)
2. Typically less than 90 V DC but can range from 5 to 120 V DC.
3. Ground cable is attached directly to the substrate
Sponge saturated with a solution of tap water/wetting agent
Maximum rate of 30 cm/s (1 linear ft/s) double stroke
Used on coatings up to 500 µm (20 mils)
May be used on concrete
4. DC - Pulsed
DC - Constant Current
5. Make sure the structure to be tested is grounded to earth
Check that the coating has cured prior to testing and no solvent fumes are present
Check that the surface is dry
Make sure adjacent workers are not touching the structure or the ground wire during testing
Never point the wand at another person
Use the appropriate voltage setting for the anticipated DFT
6. High Voltage DC Constant Current
Chapter 23: Safety Awareness
Knowledge Checks
1. A. 6 feet (2 meters)
2. C. Your employer
3. A. Verify the space has been tested and cleared for entry
B. Only intrinsically safe inspection equipment is used
C. Proper personal protective equipment is employed
D. That the workers have been properly trained
CIP Level 1
Chapter 7: Pre-Cleaning
Case Study Workshop
Possible answers may include, but are not limited to the following:
Case Study #1
1. Pinpoint rusting may occur. It will also require excessive amounts of coating to cover the surface to meet
the specified dry film thickness.
2. Report the non-conformance as dictated by the Specification. Reporting may include the contractor,
owner’s representative, and any other relevant stakeholders.
3. Consult the coating manufacturer and ask if the thickness of the IOZ can be increased to cover the surface
profile without mud cracking.
Alternatively, change the IOZ primer to an organic zinc-rich epoxy primer that is heavier and will cover the
profile. Remember that changing any part of the Specification requires the owner’s “written” permission.
Case Study #2
1. A combination of elevated temperatures, high humidity, and windy conditions can result in the formation
of dry spray.
Inorganic zinc-rich coatings dry very fast as the solvents are highly volatile and evaporate quickly.
Air temperature and wind speed were too high, causing the solvents to evaporate out of the coating
before they hit the substrate.
2. Waiting until air temperatures, relative humidity, and wind speed levels are lower will help eliminate all
the application issues experienced.
Check with the coating manufacturer to see if a slower evaporating solvent could be added to the coating
in order to slow the drying/curing process.
Case Study #3
1. The inspector could have met with the contractor prior to blast cleaning and used SSPC-VIS 1 to come to
an agreement on the initial grade of the steel and the photographic representation in VIS 1 that identifies
the specified degree of cleanliness required.
2. The inspector should meet with the contractor, share a copy of the standard, and explain the written
requirements.
3. NACE No. 2/SSPC-SP 10 clearly states that only 5% of every 9 sq. inches can have evidence of residual
staining, meaning all the mill scale needs to be removed.
The only way to meet the requirements of the specification is to have additional surface preparation
performed.
If the contractor chooses to leave the areas as is, issue a non-conformance and require a corrective action
with a copy submitted to the contractor and the owner.
© NACE International
Chapter 7: Pre-Cleaning
Case Study #4
1. Over thinning of the coating, improper spray tip size, poor application technique.
2. Notify the owner's representative or engineer and seek guidance on the repair.
Meet with the owner, contractor, and manufacturer to discuss possible options.
If the contractor chooses to leave the areas as is, issue a non-conformance and require a corrective action
with a copy submitted to the contractor and the owner.
Elevated Water Tank Lab
AMPP CIP
Date: April 13, 2022
Daily Coating Inspection Report
Day of Week: S
Project/Client:
ACME Municipal Authority
Inspector Name:
Location:
Jane Smith
M
T
W
T
F
S
Perth, Australia
Inspector Signature:
Jane Smith
Description of Area and Work Performed:
Copy to:
Attachments:
Removal and replacement of the exterior coating
of a 50-year-old elevated potable water storage
tank.
 Owner
 Contractor
N/A
 ________________
 Lab Worksheet
 NCR
N/A
 _______________
Tank is located near the beach.
Contractor: Globex Coating Contractors
Hold Point Inspection Performed
 Weather and site conditions
 Pre-surface prep, initial condition, and cleanliness
 Surface preparation monitoring
 Post surface preparation cleanliness and profile
 Mixing/thinning and application monitoring
 Post application and application defects
 Dry film thickness and curing
 Corrective actions follow-up and final inspection
Remember! Never leave any blank fields on your reports. Always write “N/A” or cross out the line item as
shown.
CIP Level 1
Chapter 7: Pre-Cleaning
Surface Conditions
 New
 Maintenance  Primer
 Steel  Concrete
 Galvanized
Condition Before Surface Prep:
Visual Standard/Guide:
 Paint
 Age
 Stainless Steel
 Dry
 Aluminum
 Cure
N/A
____________
 Rust Grade A  Rust Grade B  Rust Grade C  Rust Grade D
 SSPC-VIS 1
 SSPC-VIS 3
 ISO 8501-1
N/A
____________
 Mill Scale
 Pitting
 Laminations
 Weld Splatter
 Lead/Heavy Metal
 Oil
 Moisture
 Sharp Edges
 Rust
Soluble Salts
 ___________________
No (Fail)
Acceptable (Yes or No) _____________________
Bresle Patch & Conductivity Meter
Test: ______________________________________________________
40 µm/cm
µs/cm
 Cl ______________________
N/A
µs/cm
 Cl ______________________
2
Peeling Paint
 Painted Surface Condition ________________________________
Dry to:
 Abrasion
 Runs/sags
 Holidays
 Cracking
 Fisheyes/Cissing  Overspray
 Dry Spray
N/A
 pH ______________________
 Touch  Handle  Recoat
Amine Blush
 _______________________________
Comments:
Amine blush was observed. No other application defects were visible at the time of
inspection on Thursday, April 14, 2022, at 9:23 a.m.
Ambient Conditions
Air Temp
(Dry Bulb)
Wet Bulb
Wet Bulb
Depression
Relative
Humidity
No standard answers to
Ambient Conditions section.
Dew Point
Surface
Temp
Delta T
Other acceptable answers include pressure
washing or steam cleaning.
Surface Preparation
 Equipment Condition Check  Water/Oil Trap Check
 Solvent Clean
 Hand Tool
 Power Tool
N/A Blast Hose Size: ________
N/A
Air Supply CFM: ________
 Abrasive Blast
Waterjetting
__________________________
 Precleaning:
Recyclable Steel Grit
Abrasive Type: ______________________________________
No
Oil Content or Dust Visible: (Y/N) ____________________
785 Kpa (110 psi) Kpa/psi
Nozzle Size/Pressure: _______________________
Pass
Air Supply Cleanliness: ________________________
Comments:
Testing revealed that excessive salts had collected at the bottom of the tank. This was
probably due to rain and condensation that washed the salts down from the top to the
bottom of the tank. Additional precleaning in the form of waterjetting was performed
in this area prior to blasting.
© NACE International
Chapter 7: Pre-Cleaning
Surface Cleanliness and Profile Measurement
Cleanliness After Surface Prep:
 NACE No. 3/SSPC-SP 6  NACE No. 2/SSPC-SP 10  Unacceptable
50 - 87.5 µm (2 - 3.5 mils)
Profile Specified: ____________________________________
Profile Check:

SPG / Elcometer 224
Gauge Type: Positector
________________________________________
 Disc: Profile Achieved: __________ mils/µm  Tape: Profile Achieved: _________mils/µm
Gauge: Profile Achieved: ____________mils/µm
Surface Effect on DFT Gauge/BMR: _____________ mils/µm
No standard
answers.
Coating Application
 Stripe Coat
 Primer
 Intermediate
ABC Company Epoxy (white)
Product Name/Color: ________________________________
Quantity Mixed:
10 gal (topcoat)
Mix Method:
 Topcoat
ABC Company Polyurethane (blue)
Product Name/Color: _______________________________
Shear
mixing blade
Quantity Thinner Added:
Did not observe Mix Finish Time: __________________
2:15 p.m.
Mix Start Time: ___________________
4 hours
Pot Life: _____________________
 Conventional
15 min
Induction: ____________________
 Airless
 Touch-Up
 Brush
10%
No
Strain/Screen:Y/N _________________
58° F
Paint Temperature: _______________
C/F
 Roller
 ________________
Comments:
Mixing and thinning of the primer coat was not witnessed.
Dry Film Thickness
Pull-off and Elcometer 452 or Positector 6000 Specified Standard: _____________________
SSPC-PA-2
Gauge Type: Magnetic
______________________________________________________
Primer: Min: __________ mils/µm
Primer: Max: __________ mils/µm
Primer: Average: __________ mils/µm
Topcoat: Min: __________ mils/µm
Topcoat: Max: __________ mils/µm
Topcoat: Average: __________ mils/µm
125 - 175 µm (5 - 7 mils) mils/µm Topcoat DFT Specified: ______________________
37 - 50 µm (1.5 - 2 mils) mils/µm
Primer DFT Specified: ______________________
Total System Average DFT: _________________________________________________ mils/µm
No standard
answers.
 Unacceptable
CIP Level 1
Chapter 7: Pre-Cleaning
Date: April 13, 2022
AMPP CIP
Day of Week: S
Nonconformance/Corrective Actions Report
Project/Client:
Location:
ACME Muncipal Authority
Inspector: Jane Smith
Perth, Australia
Owner
T
W
T
F
S
Jane Smith
Contractor: Globex Coating Contractors
Copy to:

M
Attachments:


Contractor
___________________

Stop Work Order

______________
Referenced Procedure, Specification, or Standard:
1. Task 3 - Soluble Salts
2. Task 7 - Coating Application
3. Coating Defects
Description and Location of Nonconformance:
1.
Excessive salt content on the underside of the tank measured at 40 μg/cm2 when the specification
states that acceptable levels must be below 10 μg/cm2.
2A. Wrong thinner – ABC Company T1 thinner was specified, but T10 thinner was used.
2B. Topcoat induction time was too short – 30 minutes was specified, but induction was observed
starting at 2:15 p.m. and ending at 2:30 p.m. when paint application began.
2C. Dry to recoat time was too short – 5 hours was specified. Primer application was observed at
ending at 12:30 p.m. and topcoat application began at 2:30 p.m.
2D. Wrong paint temperature – 77 °F was specified, but when measured, paint temperature was 58 °F.
3.
A portion on the side of the tank that faces west was not top coated. Amine blush was visible on
the epoxy primer coat.
Discussion and Recommendations:
1.

Replace

Repair

Rework

Use As-is
Salts – additional precleaning should be performed on the bottom of the tank .
2A-C. Paint should be re-mixed per the specification.
2D.
The recoat times stated on the PDS for cooler temperatures need to be followed.
3.
Amine Blush – the specification states that the surface must be top coated. Top coating over
amine blush will result in delamination. Therefore, the manufacturer should be consulted on the
proper procedure to remove the blush.
© NACE International
Chapter 7: Pre-Cleaning
Corrective Actions:
1.
Acceptable precleaning methods are pressure washing, steam cleaning or waterjetting.
2A. Remix paint using the correct thinner (ABC Company T10).
2B. The mixed paint should sit for the full induction period of 30 minutes.
2C. The structure shall not be top coated until the minimum dry to recoat time of 5 hours has elapsed.
2D. Allow for extra time for cooler temperatures and extended recoat time.
3.
Per the manufacturer’s recommendations, the blushed surface should be wiped down with a rag
using a mild detergent mixed with clean water until a uniform color and sheen can be seen on the
surface.