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2. Dark staining adjacent to welds. 2. Dark staining adjacent to welds. 2. Dark staining adjacent to welds. 2. Dark staining adjacent to welds. 2. Dark staining adjacent to welds. Preparationchemicals entering unsealed overlaps or through poorquality welds boil out of the connection duringgalvanizing and cause surface contamination andcoating misses during galvanizing. Also, anhydrousfluxing salts left in the connection will absorbatmospheric moisture and leach out onto the adjacentgalvanized surface. Leaching of these salts willeventually reach equilibrium. Affected area should bewashed clean to remove slightly corrosive leachate.

Australian Standard AS1650, Section 1.6 AS1650, Section 1.6 AS1650, Section 1.6 AS1650, Section 1.6 AS1650, Section 1.6 - Appearance (Page 5) defines the requirement for hot dip galvanizedcoatings as follows:

The galvanized coating shall be continuous, as smooth and evenly distributed as possible, and free from defects that are detrimentalThe galvanized coating shall be continuous, as smooth and evenly distributed as possible, and free from defects that are detrimentalThe galvanized coating shall be continuous, as smooth and evenly distributed as possible, and free from defects that are detrimentalThe galvanized coating shall be continuous, as smooth and evenly distributed as possible, and free from defects that are detrimentalThe galvanized coating shall be continuous, as smooth and evenly distributed as possible, and free from defects that are detrimentalto the stated use of the coated article. Methods recommended for the renovation of damaged galvanized coatings or uncoatedto the stated use of the coated article. Methods recommended for the renovation of damaged galvanized coatings or uncoatedto the stated use of the coated article. Methods recommended for the renovation of damaged galvanized coatings or uncoatedto the stated use of the coated article. Methods recommended for the renovation of damaged galvanized coatings or uncoatedto the stated use of the coated article. Methods recommended for the renovation of damaged galvanized coatings or uncoatedareas are given in Appendix F (of AS 1650).areas are given in Appendix F (of AS 1650).areas are given in Appendix F (of AS 1650).areas are given in Appendix F (of AS 1650).areas are given in Appendix F (of AS 1650).

Notes:Notes:Notes:Notes:Notes:1.1.1.1.1. Defects cannot be completely quantified. When the presence, size or frequency of any defects in the coating are consideredDefects cannot be completely quantified. When the presence, size or frequency of any defects in the coating are consideredDefects cannot be completely quantified. When the presence, size or frequency of any defects in the coating are consideredDefects cannot be completely quantified. When the presence, size or frequency of any defects in the coating are consideredDefects cannot be completely quantified. When the presence, size or frequency of any defects in the coating are considered

to be of concern, appropriate arrangements should be made between the purchaser and the manufacturerto be of concern, appropriate arrangements should be made between the purchaser and the manufacturerto be of concern, appropriate arrangements should be made between the purchaser and the manufacturerto be of concern, appropriate arrangements should be made between the purchaser and the manufacturerto be of concern, appropriate arrangements should be made between the purchaser and the manufacturer.This may be.This may be.This may be.This may be.This may beachieved by the provision of acceptable samples or methods of test.achieved by the provision of acceptable samples or methods of test.achieved by the provision of acceptable samples or methods of test.achieved by the provision of acceptable samples or methods of test.achieved by the provision of acceptable samples or methods of test.Where defects are present and the product is submitted for acceptance, the manufacturer should be able to demonstrateWhere defects are present and the product is submitted for acceptance, the manufacturer should be able to demonstrateWhere defects are present and the product is submitted for acceptance, the manufacturer should be able to demonstrateWhere defects are present and the product is submitted for acceptance, the manufacturer should be able to demonstrateWhere defects are present and the product is submitted for acceptance, the manufacturer should be able to demonstratefitness for purpose.fitness for purpose.fitness for purpose.fitness for purpose.fitness for purpose.

2.2.2.2.2. A thickerA thickerA thickerA thickerA thicker, less smooth coating is obtained on job galvanized articles compared with continuously galvanized sheet or wire., less smooth coating is obtained on job galvanized articles compared with continuously galvanized sheet or wire., less smooth coating is obtained on job galvanized articles compared with continuously galvanized sheet or wire., less smooth coating is obtained on job galvanized articles compared with continuously galvanized sheet or wire., less smooth coating is obtained on job galvanized articles compared with continuously galvanized sheet or wire.3.3.3.3.3. (Not applicable to general hot dip galvanized products)(Not applicable to general hot dip galvanized products)(Not applicable to general hot dip galvanized products)(Not applicable to general hot dip galvanized products)(Not applicable to general hot dip galvanized products)4.4.4.4.4. The finish of the coated object may be partly or wholly grey in colour for steels of certain composition or articles that areThe finish of the coated object may be partly or wholly grey in colour for steels of certain composition or articles that areThe finish of the coated object may be partly or wholly grey in colour for steels of certain composition or articles that areThe finish of the coated object may be partly or wholly grey in colour for steels of certain composition or articles that areThe finish of the coated object may be partly or wholly grey in colour for steels of certain composition or articles that are

slowly cooled after galvanizing. Provided that such a coating has adequate adhesion, the grey finish is not detrimental,slowly cooled after galvanizing. Provided that such a coating has adequate adhesion, the grey finish is not detrimental,slowly cooled after galvanizing. Provided that such a coating has adequate adhesion, the grey finish is not detrimental,slowly cooled after galvanizing. Provided that such a coating has adequate adhesion, the grey finish is not detrimental,slowly cooled after galvanizing. Provided that such a coating has adequate adhesion, the grey finish is not detrimental,although premature staining may occur in service.although premature staining may occur in service.although premature staining may occur in service.although premature staining may occur in service.although premature staining may occur in service.

5.5.5.5.5. Advice on the transport and storage of galvanized articles is given in Appendix G (of AS 1650)Advice on the transport and storage of galvanized articles is given in Appendix G (of AS 1650)Advice on the transport and storage of galvanized articles is given in Appendix G (of AS 1650)Advice on the transport and storage of galvanized articles is given in Appendix G (of AS 1650)Advice on the transport and storage of galvanized articles is given in Appendix G (of AS 1650)

Welding slag left on or in welds will not beremovedby the galvanizing process and will result uncoatedareas on welds.

Unsealed welds where preparation chemicalspenetrate the overlap cause blowouts which causesurface contamination and subsequent coating defects.

Ash is a by-product of the galvanizing process thatfloats on the surface of the bath. Ash should bebrushed off during inspection and dressing.

INSPECTION OF GALINSPECTION OF GALINSPECTION OF GALINSPECTION OF GALINSPECTION OF GAL VVVVVANIZED PRODUCTSANIZED PRODUCTSANIZED PRODUCTSANIZED PRODUCTSANIZED PRODUCTS

GALGALGALGALGALVVVVVANIZED COAANIZED COAANIZED COAANIZED COAANIZED COA TING APPEARANCETING APPEARANCETING APPEARANCETING APPEARANCETING APPEARANCEAND DEFECTSAND DEFECTSAND DEFECTSAND DEFECTSAND DEFECTS

There are a number of common types of defects arisingfrom the hot dip galvanizing process. An explanationof the causes of defects and variations in appearancefollows:

1. Ungalvanized weld ar1. Ungalvanized weld ar1. Ungalvanized weld ar1. Ungalvanized weld ar1. Ungalvanized weld areas.eas.eas.eas.eas. Coating misses on weldareas are caused by the presence of welding slag on thewelds. All welding slag must be removed by thefabricator prior to despatch to the galvanizer. Theseareas require repair.

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INSPECTION OF GALINSPECTION OF GALINSPECTION OF GALINSPECTION OF GALINSPECTION OF GALVVVVVANIZED PRODUCTS (CONTANIZED PRODUCTS (CONTANIZED PRODUCTS (CONTANIZED PRODUCTS (CONTANIZED PRODUCTS (CONT.).).).).)

Chain marks are unavoidable when galvanizing largeitems. These defects are normally buffed off duringdressing and inspection

Drainage spikes are formed when moltez zincfreezed while draining from horozontal surfaces.Most 3 dimensional sections will always generatedrainage spikes in one plane. These are removedby buffing during dressing and inspaction.

3. Dull gray or mottled coatings. 3. Dull gray or mottled coatings. 3. Dull gray or mottled coatings. 3. Dull gray or mottled coatings. 3. Dull gray or mottled coatings. Reactive steels willgenerate thicker galvanized coatings that are duller thanstandard coatings. These coatings have longer lifebecause of their greater thickness and their appearanceis a function of steel metallurgy and generally beyondthe control of the galvanizer.

4. Dr4. Dr4. Dr4. Dr4. Dross pimples/inclusions.oss pimples/inclusions.oss pimples/inclusions.oss pimples/inclusions.oss pimples/inclusions. Dross is formed in thegalvanizing process in the form or zinc-iron crystals(approx 95% zinc - 5% ir 95% zinc - 5% ir 95% zinc - 5% ir 95% zinc - 5% ir 95% zinc - 5% irononononon) with a higher meltingpoint that the metal in the zinc bath. Dross trapped inthe galvanized coating may give the coating a rough orgritty appearance. The presence of dross inclusions inthe coatings is not detrimetal to the coating'sperformance as the corrosion resistance of zinc drossis identical to that of the galvanized coating

5. White storage staining.5. White storage staining.5. White storage staining.5. White storage staining.5. White storage staining. After galvanizing, itemsstored or stacked in wet, poorly ventilated conditionswill react with atmospheric moisture to form bulkywhite zinc hydroxide deposits on the surface of thegalvanized coating.

6. Ash staining.6. Ash staining.6. Ash staining.6. Ash staining.6. Ash staining. Zinc ash is formed in the galvanizingprocess as the work is immersed in the zinc. The ashformed is skimmed off the surface of the molten zincprior to withdrawing the work from the galvanizingbath. Sometimes, ash is trapped inside inaccessibleareas and sticks to the outside of the coating as thework exits the bath. Ash may leave a dull surfaceappearance or a light brown stain after removal. It doesnot affect the performance of the galvanized coating.

7. Striations and general surface irr7. Striations and general surface irr7. Striations and general surface irr7. Striations and general surface irr7. Striations and general surface irregularities.egularities.egularities.egularities.egularities.Ridges and lines thicker than the adjacent galvanizedcoating are caused by different rates of reaction of thezinc with the steel surface due to stress areas on thesteel surface or the presence of weld areas or weld metalwith modified metallurgy to the parent metal. Thisphenomenon is most commonly encounted on pipe andtube products.Coating performance is unaffected

8. Runs, drainage spikes and puddling. 8. Runs, drainage spikes and puddling. 8. Runs, drainage spikes and puddling. 8. Runs, drainage spikes and puddling. 8. Runs, drainage spikes and puddling. These defectsare unavoidable in the hot dip galvanizing of generalitems and are acceptable as long as they do not interferewith the assembly of the function of the item or presenta safety hazard in handling or service.

9. Bar9. Bar9. Bar9. Bar9. Bare patches.e patches.e patches.e patches.e patches. Uncoated areas on the surface ofgalvanized work are due to poor surface preparation;inadequate pretreatment in degreasing, pickling and pre-fluxing. These areas must be repaired using arecommended repair method or the item regalvanizedif the defect is of sufficient size.

Dross pimples are formed when dross crystalspresent in the molten zinc are caught up in thecoating, giving the surface a grity appearance.(lowersection). The textures and striated galvanizedsurface on the upper steel component is caused bythe surface metallurgy of the steel producingdiffering micro reactive zones on the surface.

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Galvanizing appearance and defects (cont)Galvanizing appearance and defects (cont)Galvanizing appearance and defects (cont)Galvanizing appearance and defects (cont)Galvanizing appearance and defects (cont)

10. Rust staining.10. Rust staining.10. Rust staining.10. Rust staining.10. Rust staining. Uncoated steel in contactwith galvanized coatings will accelerate corrosion ofthe coating and stain the coating brown in the area ofcontact. This can be removed by wire brushing.

Hot dip galvanized coatings will be stained by contactwith rusty steel or timber in outdoor exposureconditions. Contact with scrap steel will acceleratelocal consumption of the galvanized coating. Timberstaining can be avoided by using seasoned timber ofthe right variety.

Industrial Galvanizers Services

Industrial Galvanizers Corporation has a network ofhot dip galvanizing operations throughout Australia andin South East Asia and the USA.

The group processes over 100,000 tonnes of steelannually and offers a range of specialised servicesassociated with the efficient provision of hot dipgalvanized coatings to steel.

Some of the groups hot dip galvanizing capabilitiesinclude:

- 24 hour turnaround on negotiated contractgalvanizing.

- Heavy lift galvanizing (exceeding 20 tonnes) inspecific plants.

- Large bath sizes in most major centres toaccommodate long or wide fabrications

- Project management capabilities to co-ordinatesteel to construction site.

- Design assistance in detailing project steelworkto facilitate galvanizing and reduce coating timeand cost.

This Hunter Valley (NSW, Australia) coal mineconstruction illustrates Industrial Galvanizers abilityto supply widely based projects. Steel for this projectwas galvanized in Industrial Galvanizers facilitiesin Brisbane, Newcastle, Sydney and Melbourne.

111111. Delamination.1. Delamination.1. Delamination.1. Delamination.1. Delamination. Very heavy galvanizedcoatings (over 250 microns250 microns250 microns250 microns250 microns thick) may be brittleand delaminate from the surface under impact andrequire more careful handling in transport and eraction.Thin, cold rolled items with very smooth surface finishand manufactured from reactive steel may also giverise to coating delamination.

12. Black spots. 12. Black spots. 12. Black spots. 12. Black spots. 12. Black spots. Scattered black spotting isdue to residual galvanizing flux crystalising on thesurface of the work and is generally due to poor rinsingafter galvanizing or flux contaminated rinse water. Thisdefect is usually encountered from galvanizing bathsusing the ̀ wet' galvanizing process where the flux is ontop of the molten zinc. Excess aluminium in thegalvanizing bath can also give rise to this defect.

13. Spangled coatings.13. Spangled coatings.13. Spangled coatings.13. Spangled coatings.13. Spangled coatings. Some hot dipgalvanized coatings exhibit a high level of ̀ spangling'caused by zinc crystal patterns on the surface. Thisphenomenon arises with galvanizing alloys producedin particular smelting processes and these alloys arecommonly used for hot dip galvanizing. There is nodifference in coating performance.