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Coating ReportRed discoloration has been removed.Coating thickness is just below the minimum prescribed in SANS 3575, which for Z275 is 13.5µm.While the coating thickness readingstaken on site by means of a calibratedelectro-magnetic thickness gauge weregenerally slightly higher than thatrequired in the specification, it isworthwhile to bear in mind thatreadings done in this manner may onlybe used as an approximation. Shouldaccuracy proving coating thickness forany reason be required, samples will benecessary for stripping purposes.Conclusion andrecommendationsSafe StorageLocation of coating Mean Min Max No of readingsthickness readingsGeneral 23 59 37 43White rust removed 32 21 43 31Red rust area 1 26 8.5 55 # 27Red rust area 2 33 10.1 69 # 31# – While every effort was taken during the coating inspection to remove all contaminants priorto measuring the residual coating thickness, sometimes contaminants remain, resulting in theimpression that the coating is thicker than specified.Coating thickness readings (µm).regularly to ensure that moisturedoes not penetrate the stock.To prevent unnecessary damage to hotdip galvanized or colour-coated sheets,proper measures should be taken toprevent contamination by moisturewhile the material is still bundled ornested in stacks.If not required for immediate use, coilsor packs of sheets must be stacked onsite under properly designed cover,clear off the ground and protected fromwind driven rain. Plastic tarpaulins,which completely envelop packs ofsheets or coils should not be used, as asudden drop in ambient temperaturemay cause condensation of watervapour, which can easily be drawn inbetween nested sheeting by capillaryaction.Ideally, deliveries of hot dipgalvanized and colour-coated steelsheet to the building site should bescheduled for a storage period of notlonger than two weeks prior toinstallation. Inspect the storage siteHowever, although the procedure ofsafe packaging of sheeting duringtransport and site storage is wellknown within the galvanizing industryand others, it would be appropriate ifthe sheeting supplier made this knownto customers such as this customer atthe time of delivery, so that effectiveprevention methods of wet storagestain could have been put in place.Coating repair:1. Rub red rusted and heavy whiterusted areas (including any areasunderside the sheeting on theinside of the building see photoright) with steel wire wool toremove all corrosion products.2. Remove all dust and debris.3. Clean compromised areas and ifrequired the entire sheeted surfacewith a water soluble degreaser andscotch brite pads.4. Thoroughly remove all residualThoroughly clean all heavily white rusted areason the undersides of the sheeting of thebuilding prior to any subsequent coating repair.chemicals with running water,obtain a “water break free surface”.5. Apply one coat of “Zincfix” (seeattached) to 100µm DFT to allcompromised areas and overlap thesurrounding unaffected coating byat least 20mm. Wait to dry.6. If required, apply one or two coatsof water based acrylic paint to aDFT per coat of 40µm or equal.Terry Smith32 Hot Dip Galvanizing Today Volume 4 Issue 1 2007
Walter’s CornerWalter’s CornerThe hot dip galvanizing industry is alive and wellDuring the past few months, therehas been an unprecedented increasein the demand for hot dipgalvanizing as a means of corrosioncontrol. This has resulted intemporary delays and inconveniencefor end users as the industry strivesto adjust to the increase in demand,which is confidently expected tocontinue indefinitely.The predictable and reliableproperties of a hot dip galvanizedcoating for corrosion control havecontributed towards this significantincrease in popularity over the yearsof a coating process which was firstintroduced more than a century anda half ago.The following statistics showconvincingly the substantial increasein demand for hot dip galvanizedsteel during recent years. It shouldbe noted that these statistics (table10) exclude hot dip galvanized wireand continuously galvanized sheet.Hot dip galvanizing is indeed aprocess that can be described as oldyet ever new.The rapid and in some instancesunanticipated increase in quantitiesof steel requiring hot dip galvanizinghas resulted in undesirablyprotracted delivery schedules whichcan impact adversely on completionprogrammes for some projects. Thegalvanizing industry has been madeacutely aware of this negativesituation with the result that manygalvanizers throughout the countryare presently installing additionalfacilities in order to increaseproductive capacity. Dimensionally,the bath sizes in South Africa areequal to the best worldwide withlengths ranging up to 14m in length,2m in width and even 4m deep insome cases.Volume 4 Issue 1 2007 Hot Dip Galvanizing Today 33
Page 1: 2007 Volume 4 Issue 1HOT DIP GALVAN
Page 4 and 5: CommentsExecutive Director’sComme
Page 6 and 7: Continuous hot dip galvanized sheet
Page 10: Continuous hot dip galvanized sheet
Page 15 and 16: ADVERTORIALSHAPING THE FUTURE OF ST
Page 20 and 21: Safety and security including conti
Page 26 and 27: Duplex CoatingsA life cycle costing
Page 28 and 29: Duplex CoatingsHot dip galvanized a
Page 30 and 31: Duplex Coating ReportDuplex coated
Page 32 and 33: Coating ReportWet storage stain and
Page 36: Walter’s CornerThe durability of
Page 40 and 41: Member’s NewsRobor acquisition fi
Page 42 and 43: Personality Profilethat nobody woul
Page 44 and 45: Guest WriterBob Andrew, our guest w
Page 46 and 47: Case Studyperformance of hot dip ga
Page 48: HOT DIP GALVANIZING MEMBERSGALVANIZ

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