WELDING INSPECTION AND QUALITY CONTROL
Upon completion of this module you will be able to:
1. Identify the different inspection methods used in non
destructive testing.
2. The uses and the limitations of the different inspection
methods.
3. Perform Visual Inspection.
 Introduction.

Inspection, Testing and qualification are
growing part of
QUALITY CONTROL in
manufacturing and maintenance. Quality Control has
become very important because of competition and
liability. To compete in what has become a global
marketplace, companies must produce the best
products possible. The cost of inspection and testing
of products can save greater expenses later on when
the consumer becomes involved. Money that does not
have to be spent defending the company can be used
for research and development of new products. The
WELDER is the person who begins quality control by
being satisfied only with Quality Welding.
The welder starts the inspection in the process of
welding, making immediate adjustment in response to
what is being observed in the weld pool. This may
require changing the amperage, the travel speed, the
arc length or any of the factors that affects quality of
the weld bead. Finally, the welder gives the completed
weld a final Visual Inspection to look for any defects
that could not be seen while welding.
Common methods used in NDE
 Visual Inspection (VT)
 Magnetic Particle Inspection (MT)
 Liquid (Dye) Penetrant Inspection (PT)
 X-Ray inspection (RT)
 Ultrasonic testing (UT)
 Air or water pressure testing (LT)
VISUAL INSPECTION – VISUAL TEST (VT)
What is Visual Inspection?
A. NDT process – non destructive testing is the original term
used to identify a method of inspection that does not destroy a
product usefulness. Current terms include nondestructive
inspection (NDI) or nondestructive evaluation or examination
(NDE)
B. Examination with the eye – therefore you are only able to
DETECT SURFACE DISCONTINUITIES.
C. Most important and most extensively used NDE/NDI/NDT
method (before any NDT or DT be applied.)
II. Advantages
A. Usually inexpensive - the majority of expense will be in the
inspector’s wage.
B. Equipment is small and inexpensive – there’s a lot of
equipment to aid in visual inspection, but all small and
inexpensive.
I.
C. No powered required – this makes VT the most portable NDT
process.
D. Can avoid defects and costly repairs – by able to make
intermittent inspection
II. DISADVANTAGES
A. Requires training and experience –the inspector should be
familiar with all the welding process.
B. Must have a good eyes – the AWS requires 20-40 natural or
corrected distance acuity for a certified welding inspector.
C. May not detect internal defects – limited to surface
discontinuities only, but it might give indication of substance
indication. Then can be supplemented by some other NDT
method.
D. No permanent records – the inspector must maintain a written
log, supplemented by pictures, and tape recorded report.
E. Subject to human error – must spend adequate time to prevent
errors.
IV. Five steps of Visual Inspection.
A. Inspection practice – establish a definite procedure to insure
adequate and consistent coverage.
B. Inspection prior to welding
C. Inspection during welding
D. Inspection after welding
E. Marking and making repairs
V. Equipment required.
A. Flashlight – used to remove shadows when an extension lamp
can’t be used.
B. Magnifying glass – low power can be used with caution, if
allowed by customer or code.
C. Protective lenses – pocket viewer with proper shade lens to
watch the welding taking place.
D. Weld gage – are hand held measuring devices used to assist
during welding and for final inspection.
E. Hammer and chisel – to remove spatter or slag from weld prior
to inspection.
F. Temperature Indicating Devices – some method must be used
to determine the preheating, interpass and postheating
temperatures. Pyrometer and tempelstick or crayons are
commonly used.
G. Magnet – a magnet can be used to help determine a material
type.
Visual Inspection (VT)
 Fillet gauges measure
 The “Legs”of the weld
 Convexity

(weld rounded outward)
 Concavity
 (weld rounded inward)
 Flatness
Measuring Steel Rule
Magnifying Glass
Fillet Weld Gauge
Palm Weld Gauge
Micro Caliper
Vernier Caliper
VI. Inspection Before Welding
A. Drawing – drawing are complete and accurate?
B. Position of welds – does the position called for correspond to
the procedure or specification? In vertical is direction of travel
correct?
C. Welding symbols – if they are used are they complete and
accurate?
D. Welding procedure – is the procedure complete and accurate
according to the code or specification?
E. Material
1. Did purchasing obtain the correct material such as base
metal type and size. The correct electrode type size and the
correct shielding gas type and grade.
2. Materials should be checked for defects. Base metal should
be checked rust, mill, scale, laminations or delaminations.
3. Is the material preparation correct and according to
procedure, such as angles and condition after preparation.
F. Assembly
1. Inspect for proper fit up, as this will prevent discontinuities
from occuring.
2. Jigs and fixtures will assure proper alignment. Make sure they
are clean and free spatter and not damaged.
3. The tack welds are only short welds, but the quality must be
the same as all other welds. The tack welds must be made
with the same electrodes that are used for the rest of the
welds.
4. Pre heat will be used to slow the cooling rate and prevent
distortion. The pre heat could be used prior to tacking and / or
prior to welding.
G. Equipment
1. Inspect the equipment for any damaged such as damaged
cables, damaged ground clamps, or electrode holders. Inspect
the arc voltage and amperage meters making sure they are
with in range.
Welder Inspect before welding
- Root Face
- Root Gap
- Bevel Angle
- Joint and Fit up
VII. Inspection DURING welding.
A. Electrodes – inspect for usage of proper electrodes, types,
size and storage. Low hydrogen type must be stored in a
stabilizing oven.
B. Root pass – the first layer or root pass is the most important
and is particularly susceptible to cracking. Thicker material
will crack and will require more pre heat.
C. Subsequent passes – inspection of successive layers is
sometimes carried out with the assistance of workmanship
standard. Check for contour or undercut as these are good
places for slag to be trapped. Check for proper cleaning
between passes as this can prevent slag entrapment.
D. Crater formation – make sure crater are filled as this are areas
where crack are easily formed.
E. Weld size and sequence – are the weld size according to the
print and is the layer and sequence according to the procedure?
The use of various gages will determine this.
VIII. Inspection After welding
A. The applicable code or standard – it will list acceptance
standards They will generally cover the following areas;
1. Weld size – use gages to check conformance to prints
2. Contour and finish – is the contour convex or concave, and
what was called for in print? Is finish smooth and free from
surface irregularities.
3. Cracks – the code or standard will state if any is acceptable
and what size.
4. Overlap – it is an indication of lack of fusion
5. Undercut – if allowed how much?
6. Spatter – what is excessive?
IX. Making repairs
A. When marking areas to be repaired the marking should be
positive and clear. It should be a method that is understood by
all involved, should be permanent enough to be evident after the
repair has been made and inspected, and the marking must not
damaged the part.
Non Destructive Testing – Dye Penetrant Test
OBJECTIVE:
Upon completion of this module you will be able to:
1. Understand that both Inspection and Testing are
necessary for Quality Welding.
2. Identify the different inspection methods used in Non
Destructive Testing and Destructive Testing
3. Describe the uses, the process and the limitations of
the different non destructive inspection methods.
4. Perform Dye Penetrant Testing.
TESTING

Testing becomes necessary for several reasons. If new
welding procedures are employed, the manufacturer
might be interested in finding out if the welding process
is producing quality welds. For example, a product welded
by Shielded Metal Arc Welding may be produced more
cost-effectively by a Gas Metal Arc Welding process, but
will the quality be the same? The manufacturer may be
interested in finding out if both the gas metal arc welding
process and the filler metals are compatible with the steel
used as the base metal. If the steel does not match up with
the filler metal, no welding will make any difference.
There might also be the question of whether the welders
have enough skill at some other welding process to make
welds as sound as those made by shielded metal arc welding.
No manufacturer wants to risk the company’s reputation with
welds that fails to hold up. The least serious outcome might be
a product that fails; the worst could be injury or death.
Testing companies provide an invaluable service when it
is necessary to have welding examination outside the
manufacturer’s plant. Testing companies keep records and
furnish the results of weld testing to insurance companies,
government agencies and other interested parties. Testing
companies provide an important service because, by
uncovering problems in welding, they help manufacturers
produce safe and durable goods and structures that
consumers can live with.
TWO METHODS OF TESTING
1. NON DESTRUCTIVE TESTING - leaves the weldment
intact, at least until the results uncover major defects in the
welding. Consequently, nondestructive testing is often
preferred when testing is necessary.
2. DESTRUCTIVE TESTING - results in the destruction of
weldment. This is a costly undertaking because of the time
and money involved, not to mention the destruction of a
weldment that might have to be re-welded.
1. NON-DESTRUCTIVE TESTING METHODS
There are FOUR common methods of Non Destructive
Testing:
•Magnetic Particle test
•Dye penetrant test
•Ultrasonic test
•Radiographic test
Dye Penetrant Test (DPT) and Fluorescent Penetrant Test
(FPT) – can locate only cracks and porosity that have
formed on the surface of the weld. With the dye
penetrant test a highly penetrative liquid is applied to a
weld that has been thoroughly cleaned. Upon drying, a
developer is applied to the weld. Under normal lighting,
any defects are outlined, usually in red, where the dye has
been absorbed.
 With the fluorescent penetrant test, the weldment is
submerged in a fluorescent dye. It is removed from the
dye and placed under a black light, where any defects in
the weld appear greenish yellow.
 Defects Detected
Defects open to surface only – Cracks, slag inclusion,
porosity and undercuts.
Liquid (Dye) Penetrant Inspection (PT)
 Liquid penetrant inspection uses colored or
fluorescent dye to check for surface flaws.
 PT will not show sub-surface flaws.
 PT can be used on both metallic and non metallic
surfaces such as ceramic, glass, plastic, and metal.
 PT dose not require the part to be Magnetized.
Advantages
a. Detects very small, tight surface and subsurface imperfections
b. Simple application and easy to interpret
c. Inexpensive
d. Use in magnetic and non magnetic materials such as ceramic, plastic
Disadvantages
a. Time consuming on various steps of the process
b. Normally no permanent record
EQUIPMENTS FOR PENETRANT TEST
•Solvent Cleaner
•Penetrant
•Developer
Process Principle – 6 steps
1. Surface preparation
2. Penetrant application
3. Excess penetrant removal
4. Developer application
5. Inspection / evaluation
6. Post cleaning
 Process Principle – 6 steps
1. Surface preparation – remove oil,
grease, spatter
1.1. Apply Solvent Cleaner to the
area to be inspected
1.2. Use clean rags to remove
excess cleaner solvent
2. Apply Penetrant and wait for 15-20
minutes dwelling time
3. Remove excess penetrant using
clean rags
4. Apply Developer and wait 5 - 10
minutes dwelling time
5. Inspect and evaluate the red color
formation
6. Post cleaning
DYE PENETRANTS
DETECTION
Red Dots will appear if Defect is present. Very Red Color the defect is deep and not
very red the defect is shallow.
II. Application:
a. Ferrous and non ferrous materials
b. Plastic and glass – ceramics-insulators-anything that is nonporous
III. Advantages:
a. Low cost
b. Ease in application and interpretation – easy to apply and interpret
result, discontinuities readily visible and portable.
c. Less training time for applicator – easy process to learn.
IV. Limitations:
a. Detects discontinuities that is open to surface only
b. Can not be used on porous or absorbent materials
V. Safety
a. Ventilation – check for toxic fumes from testing materials. Check for
volatility -explosive or fire flash points
b. Fire safety – the test material maybe non flammable but the propellant
used with spray cans maybe extremely flammable.
OBJECTIVE:
Upon completion of the module, you will be able to;
1. Describe Magnetic Particle Testing and its limitations.
2. Perform Magnetic Test
 Magnetic Particle Test (MT) – (commonly referred to as
Magnaflux testing)The magnetic particle test begins
when Direct Current (DC) electric charges is passed
between two poles. The forces line up until there is a
break in these magnetic lines of force.
 Magnetic particles are applied to the weld in the form of
powder. Nothing unusual results when the welding is
sound, but when the welding might be defective, a break
is created in the lines of force. The magnetic particles
become attracted to the defect, which develops north
and south poles at the edge of the defect, outlining the
defect.
 Equipment:
1. Iron Particle, wet or dry or flourescent
2. Special power source
3. Ultraviolet light for the flourescent type
 DEFECTS DETECTED:
1. Surface and near surface discontinuities
2. Cracks
3. Porosity
4. Slag Inclusions
5. Incomplete Fusion
 Advantages
1. Detects discontinuities not visible to the naked eyes
2. Useful in checking edges prior to welding and repairs
3. No size restrictions
 Disadvantages
1. Used in magnetic materials only
2. Surface roughness may distort magnetic field
3. Normally no permanent record
To enable the formation of a proper magnetic particle pattern for
defect indication, the orientation of the defect and magnetic field
must be taken into account.
Two methods of magnetizing the weld zone.
1. The YOKE method which uses an electromagnet
2. The PRODE method in which electrode are applied to the
specimen to allow current to flow in the specimen.
- not applicable to high tensile steel since it can form a short
circuit between specimen and electrodes causing a defect
resembling an arc strikes.
- effective to detecting defects not exposed but existing near
the surface.
Two methods of magnetizing the weld zone.
2. The PRODE method in which
electrode are applied to the
specimen to allow current to flow
in the specimen.
1.
The YOKE method which uses an
electromagnet
MAGNETIC PARTICLE
Two types of magnetic particles:
1. Fluorescent type
2. Non fluorescent type
Methods of particle application:
1. Wet method – magnetic particles are dispersed by suspension
in water or kerosene and the suspension is applied to the
specimen surface.
2. Dry method –magnetic particle are dispersed in the surface of
the specimen.
Coatings
Unfortunately, ASTM E-1444 specifies that Magnetic Particle testing shall
not be performed with nonmagnetic coatings (paint, etc.) in place that
exceed 0.003" (0.08mm) in thickness, or ferromagnetic coatings
(electroplated nickel, etc.) that exceed 0.001" (0.03mm) in thickness.
That is not very thick! So be careful on those painted surfaces.......don't
forget the chance of poor bonding on those thin coatings.
Current Types
ASTM E-1444 recommends:
Half-wave rectified AC is best for the dry particle method.
For defects open to the surface use AC only.
When using Wet particle method for subsurface defects, use full-wave
rectified AC.
 Yokes
Funny, but look at the difference, Standards can make on a
procedure:
ASTM E-1444 requires DC yokes to have a lifting force of at
least 30 lbs.(small spacing) and a 50 lbs. lift for a large
spacing of legs.
ASTM A-275 requires DC yokes have a lifting power of at
least 40 lbs at 3 to 6" spacing of legs.
The ASME Boiler Code requires a DC yoke to have at least
40 lbs of lift at the maximum pole spacing.
 There is a misconception in the 'field' that one can take a
yoke and proceed with magnitizing an object by dragging the
yoke along the object's surface. Wrong!!!
If you are dragging an AC yoke, you are in fact not magnetizing
the object but rather you are doing a lovely job of
DEMAGNETIZING the object. As in ASTM E-1444 above,
paragraph 6.7.1.1, demagnetizing using a coil (yoke) by
moving the object through........(which is what you are doing).
To correctly magnetize an object, position the yoke and apply
magnetizing force for 2 - 5 seconds before moving the unit to
the next position.
So watch which specification and procedure is being
applied to your project.
Ultrasonic testing (UT)
 Ultrasonic testing (UT) is a method of determining
the size and location of discontinuities within a
component using high frequency sound waves.
 Sound waves are sent through a transducer into the
material and the shift in time require for their return
or echo is plotted.
 Ultrasonic waves will not travel through air therefore
flaws will alter the echo pattern.
ULTRA SONIC
oscilloscope
 Equipments:
1.Oscilloscope – to generate and receive ultrasonic waves.
2. Cathode Ray Tube – where the traveling distance and intensity of
reflected wave are measured to locate and determine the size of the
defect.
3.Vibrating Transducer (Probe)
3.1. Straight Beam
3.2. Angle Beam
4.Calibration Blocks – to make time distance and built in holes and notches
can be used as amplitude standards.
 DEFECTS DETECTED:
1. Can locate all internal flaws located by other methods with the addition of
exceptionally small flaws.
 ADVANTAGES
1. Extremely sensitive
2. Use restricted only by very complex weldments
3. Can be used on all materials
 DISADVANTAGES
1. Demands highly developed interpretation skill
Advantages:
a. Time to inspect – fast response / ability to inspect
from one side.
b. B. Cost - $3,500.00 machine / $200.oo transducer
c. Portable with battery pack
d. Accuracy can locate small discontinuity
Limitations:
a. Equipment
b. Operator
c. Standards
d. Reports and records




Radiographic Test (RT)
Radiographic Test is a NDT that can detect surface and internal
discontinuities using electro magnetic radiation of short duration
by means of either
1. X-Ray
2. Gamma Ray
It is a wave of energy that will pass through most materials and
develop the negative image of what it passes through on film.
Both of these methods are a danger to health
1. An X-Ray- Is electronically produced in a vacuum tube.
2. Gamma Ray-are emitted by the atomic decay.
 Two Common Source of Gamma Rays.
 Cobalt 60
 Iridium 192
 3.FILM VIEWER
 Pictures taken are viewed as negatives will only give flat
image not in three dimensional darkened area must be used
for viewing.
X- RAY
X-RAY VIEWER
Pictures taken are
viewed as negatives
will only give flat
image not in three
dimensional
darkened area must
be used for viewing
Advantages:
 A Radiograph ( X-Ray picture) is a permanent record of a weld
used for quality inspection purposes
 RT inspections can reveal flaws deep within a component
Limitations:
1. The necessity to have access to both sides of the part being
radiographed
2. Unfavorable shape and orientation of some discontinuities.
3. Radiation Safety requirements for personal protection.
4. Tight Cracks, unless they are essentially normal to the
radiation beam.
5. Shallow tight surface cracks in thick sections usually can not
be detected at all, even when properly oriented.
6. Laminations are nearly impossible to detect because their
orientation does not permit sufficient differences in the amount
of radiation absorbed through the piece being examined to
show the defect on film.
Air or water pressure testing
(LEAK TEST)
 Pressure testing or leak testing can be performed with
either gasses or liquids.
 Voids that allow gasses or liquids to escape from the
component can be classified as gross (large) or fine
leaks.
 Extremely small gas leaks measured in PPM (parts per
million) require a “Mass Spectrometer” to Sniff for tracer
gases
APPLICATION OF A LOAD
 Used to test pressure vessels
 Pipe lines
 The item for testing is filled with water or oil it is then
pressurised using a pump
 A safety valve is set 1.5 to 2 times below the
working pressure.
PRESSURE TEST
Pressure Gauge
Pump
Test Specimen
Quiz time
 True or False ?
 Dye penetrate inspections can only be used on non
magnetic material.
 Answer: False
Quiz time
 True or False ?
 X-Rays can only be used to locate flaws at or near the
surface of a weld.
 Answer: False
Quiz time
 True or False ?
 Virtually all welds have flaws.
 Answer: True
Quiz time
 True or False ?
 Magnetic particle testing can only detect flaws at or
near the surface.
 Answer: True
Quiz time
 True or False ?
 Magnet particle testing can only be done on materials
that can be magnetized.
 Answer: True
Quiz time
 The letters NDE Mean ___________ ?
A: nondestructive inspection
B: nondestructive evaluation
C: nondisruptive evaluation
D: nondestructive examination
Quiz time
 The method most often used to check for leaks as
small as one part per million (PPM) from a gas line
or cylinder is the _________ Method ?
A: hydrostatic
B: mass spectrometer
C: soap suds bubble
D: scleroscope
Modern Welding
York County School of Technology