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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
1The 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
After-Fabrication Hot Dip Galvanizing: A practical reference for designers, specifiers, engineers, consultants, manufacturers, and users, Galvanizing Association of New Zealand, website
2Definition
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
1.1Effect of molten zinc on fluxed steel surface is explained in accordance with After-Fabrication Hot Dip Galvanizing.
1.2Zinc alloy layers are compared in terms of composition and hardness.
Rangeeta, zeta, delta, gamma.
1.3Layer thickness is explained in relation to immersion, withdrawal, and mass of components.
Rangeincludes but is not limited to – alloy layer growth rate.
1.4Layer thickness is explained in terms of effect of surface texture of component.
1.5The 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
2.1Requirements for coating thickness and mass on components are identified for different steel thicknesses in accordance with NZS 4680.
Rangecomponents – centrifuged, not centrifuged;
requirements – minimum local thickness, average thickness, average minimum mass.
2.2Coating 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
3.1Mechanical properties of steel not affected by galvanizing are identified in terms of After-Fabrication Hot Dip Galvanizing.
3.2Strain-age embrittlement is explained and elements used to reduce its effect are identified in terms of After-Fabrication Hot Dip Galvanizing.
3.3Procedures for minimising hydrogen embrittlement are described in terms of After-Fabrication Hot Dip Galvanizing and company procedures.
3.4Recommendations to minimise embrittlement caused during cold work are explained in terms of After-Fabrication Hot Dip Galvanizing and company procedures.
Rangecold work – punching, shearing, bending.
Outcome 4
Demonstrate knowledge of factors affecting the protective life of galvanized coatings.
Evidence requirements
4.1The effect of environmental factors on the protective life of galvanized coatingsis explained in terms of After-Fabrication Hot Dip Galvanizing.
Rangefactors include but are not limited to – dry atmosphere, moist atmosphere, rural location, marine location, industrial location, corrosion rates underground.
4.2The effect of exposure to high temperatures on the protective life of galvanized coatingsis explained in terms of coating layer and maximum continuous temperature.
4.3The effects of underwater factors on the protective life of galvanized coatings are explained for different conditions in terms of After-Fabrication Hot Dip Galvanizing.
Rangeconditions – mains supply, pure water, water temperature, sea water.
4.4The effects of chemicals on galvanized coatings are described and the pH range is explained in terms of After-Fabrication Hot Dip Galvanizing.
Rangechemicals – acid, alcohol, alkaline, chlorofluorocarbons, detergent, petrochemicals, gas, sewage, timber preservative.
4.5Galvanic corrosion is explained in terms of causes, effects, and prevention.
Rangecauses of corrosion include but are not limited to – overlapping surfaces, copper.
Planned review date / 31 December 2019Status information and last date for assessment for superseded versions
Process / Version / Date / Last Date for AssessmentRegistration / 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
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.
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) 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 2018