NZQA registered unit standard
21183 version 3
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Title
Demonstrate knowledge of hot dip galvanizing metallurgy
Level
4
Credits
5
Purpose
People credited with this unit standard are able to demonstrate
knowledge of: zinc alloy layers on steel; galvanized coating
thickness requirements; the effect of galvanizing on properties
of steel; and factors affecting the protective life of galvanized
coatings.
Classification
Industrial Coatings > Hot Dip Galvanizing
Available grade
Achieved
Explanatory notes
1
The current version of the following documents must be complied with:
AS/NZS 4680:2006 Hot-dip galvanized (zinc) coatings on fabricated ferrous articles
(AS/NZS 4680), available at http://www.standards.co.nz;
After-Fabrication Hot Dip Galvanizing: A practical reference for designers, specifiers,
engineers, consultants, manufacturers, and users, Galvanizing Association of New
Zealand, website http://www.galvanizing.org.nz.
2
Definition
Company procedures refer to all documented policies and procedures of the
candidate’s employer at the time of training including, but not limited to, those relating
to health, safety, environment, quality, and operations.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of zinc alloy layers on steel.
Evidence requirements
1.1
Effect of molten zinc on fluxed steel surface is explained in accordance with
After-Fabrication Hot Dip Galvanizing.
1.2
Zinc alloy layers are compared in terms of composition and hardness.
Range
1.3
eta, zeta, delta, gamma.
Layer thickness is explained in relation to immersion, withdrawal, and mass of
components.
NZ Motor Industry Training Organisation
(Incorporated) (MITO)
SSB Code 101542
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
Range
21183 version 3
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includes but is not limited to – alloy layer growth rate.
1.4
Layer thickness is explained in terms of effect of surface texture of component.
1.5
The effects of silicon and phosphorus content of steel are explained in terms of
the development of alloy layer.
Outcome 2
Demonstrate knowledge of galvanized coating thickness requirements.
Evidence requirements
2.1
Requirements for coating thickness and mass on components are identified for
different steel thicknesses in accordance with NZS 4680.
Range
2.2
components – centrifuged, not centrifuged;
requirements – minimum local thickness, average thickness,
average minimum mass.
Coating requirements for threaded fasteners are described in accordance with
NZS 4680.
Outcome 3
Demonstrate knowledge of the effect of galvanizing on properties of steel.
Evidence requirements
3.1
Mechanical properties of steel not affected by galvanizing are identified in terms
of After-Fabrication Hot Dip Galvanizing.
3.2
Strain-age embrittlement is explained and elements used to reduce its effect are
identified in terms of After-Fabrication Hot Dip Galvanizing.
3.3
Procedures for minimising hydrogen embrittlement are described in terms of
After-Fabrication Hot Dip Galvanizing and company procedures.
3.4
Recommendations to minimise embrittlement caused during cold work are
explained in terms of After-Fabrication Hot Dip Galvanizing and company
procedures.
Range
cold work – punching, shearing, bending.
Outcome 4
Demonstrate knowledge of factors affecting the protective life of galvanized coatings.
Evidence requirements
NZ Motor Industry Training Organisation
(Incorporated) (MITO)
SSB Code 101542
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
4.1
21183 version 3
Page 3 of 4
The effect of environmental factors on the protective life of galvanized coatings
is explained in terms of After-Fabrication Hot Dip Galvanizing.
factors include but are not limited to – dry atmosphere, moist
atmosphere, rural location, marine location, industrial location,
corrosion rates underground.
Range
4.2
The effect of exposure to high temperatures on the protective life of galvanized
coatings is explained in terms of coating layer and maximum continuous
temperature.
4.3
The effects of underwater factors on the protective life of galvanized coatings
are explained for different conditions in terms of After-Fabrication Hot Dip
Galvanizing.
conditions – mains supply, pure water, water temperature, sea
water.
Range
4.4
The effects of chemicals on galvanized coatings are described and the pH
range is explained in terms of After-Fabrication Hot Dip Galvanizing.
chemicals – acid, alcohol, alkaline, chlorofluorocarbons, detergent,
petrochemicals, gas, sewage, timber preservative.
Range
4.5
Galvanic corrosion is explained in terms of causes, effects, and prevention.
causes of corrosion include but are not limited to – overlapping
surfaces, copper.
Range
Planned review date
31 December 2019
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
21 October 2004
31 December 2016
Review
2
23 January 2009
31 December 2016
Review
3
16 April 2015
N/A
Consent and Moderation Requirements (CMR) reference
0114
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
NZ Motor Industry Training Organisation
(Incorporated) (MITO)
SSB Code 101542
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
21183 version 3
Page 4 of 4
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR also includes useful information about special requirements for organisations wishing
to develop education and training programmes, such as minimum qualifications for tutors
and assessors, and special resource requirements.
Comments on this unit standard
Please contact the NZ Motor Industry Training Organisation (Incorporated) (MITO)
info@mito.org.nzif you wish to suggest changes to the content of this unit standard.
NZ Motor Industry Training Organisation
(Incorporated) (MITO)
SSB Code 101542
 New Zealand Qualifications Authority 2016