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W amoshaCapricorn Park – “Are the two coatingsthe same?”Capricorn ParkSouth easterly windsPhotos 1:The South Easterly winds off the coast in combination with highwave action with chlorides, relatively high humidity, distance from the sea,low lying land mass, etc. make the conditions along this coastlineextremely corrosive.Photos 2: A guard rail adjacent to the sea that has lost its coating overtime and is now corroding.“Wamosha” which in Zulu means inappropriateuse, misuse or messing about, is the name forthis column. The column will feature articleswhere we find hot dip galvanizing misused orwhere other zinc coatings that are ofteninappropriately specified when general hot dipgalvanizing is preferred, have beeninappropriately used.The Hot Dip Galvanizers Associationwas requested to inspect and commenton the performance of continuous andgeneral hot dip galvanized roofingmembers on an industrial building(No. 1) in Capricorn Park (photo 3),exposed to the atmosphere for two anda half years. The components wereinspected on Tuesday 26 January 2010and I report as follows:Capricorn Park off False Bay on thecoast side is situated about 1km fromthe sea, with the M5 entrance beingabout 2 - 2.5km from the sea.In our experience wind drivenchlorides can be found up to 3km ofthe sea along this coast line from andincluding Glencairn through to justwest of the Strand, whereas areas suchas Simonstown and Gordons Bay areconsiderably less corrosive due mainlyto the exclusion of the directonslaught of the South Easterlychloride carrying winds.Conditions within Capricorn Parkfrom the M5 gate (photo 4 and 5)through to the coastal gate off FalseBay are corrosive.The conditions at the coastal gate offFalse Bay are extremely corrosive, photo6 shows the entrance, photo 7 shows abadly painted (now failed) anglewelded to a failed duplex coated gateand photo 8 a failed powder coated wiremesh fence.This security intercom sign (photos 9 -11) was most probably installed at thetime Capricorn Park was established(December 2000) see label on back ofsign. While the pre-galvanized bracketand unistrut and zinc electroplatedfasteners are corroding, the hot dipgalvanized post shows someinteresting observations.Photos 12 - 14 show, after scraping thesurface to remove chloridePhoto 3.Photo 4. Photo 5.32 Hot Dip Galvanizing Today Volume 7 Issue 1 2010
W amoshaPhoto 6. Photo 7. Photo 8.Photo 9. Photo 10. Photo 11: Installed December 2000.contaminants, coating thicknessreadings of 57.6; 43.4 and 50.8µmrespectively, on the landside of the post.Photos 15 - 17 show, after scraping thesurface to remove chloridecontaminants, coating thickness readingsof 32.6; 8.4 and 8.6µm respectively, onthe coastal side of the post.While removal of the contaminantsmay not be 100% effective, theresultant coating thickness readingsdo indicate that there is aconsiderable coating thicknessreduction on the coastal side versusthe landside over the 10 odd years.continued on page 34...Volume 7 Issue 1 2010 Hot Dip Galvanizing Today 33
Page 1 and 2: 2010 Volume 7 Issue 1HOT DIP GALVAN
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