Featuring: - hdgasa

Bread bakery exchanger coilinvestigationW amosha“Wamosha” which in Zulu meansinappropriate use, misuse or messing about,has replaced the words, “Galvanizing Failures”.This column will feature articles where we findhot dip galvanizing or where other zinc coatingsthat are often inappropriately specified whengeneral hot dip galvanizing is preferred, havebeen inappropriately used.Following a request for the Associationto conduct a site inspection of hot dipgalvanized heat exchanger coils in abread baking cooling chamber, thefollowing report is an analyse of thecauses of the apparent failure of thecorrosion control system.At the time, it was reported that twoseparate bread cooling installationshad been commissionedapproximately 12 months before thesaid site inspection. Of these twoinstallations, one had shown serioussigns of corrosion to the point whererefrigerant had leaked, resealing andre-gassing had to be undertaken. Thisparticular installation was nonoperationalduring the visit as it wasreported that a further leak had beenencountered followed by re-sealingand a pressure test. Re-gassing was tobe completed before recommissioning.Inspection of both installationsrevealed severe corrosive attack of thecoils and fins of the non-operationalcontinued on page 32...Corrosion evident on the coil fins on the insideface of the bread cooling chamber. Note thecorrosion evident on every second pipe withinthe heat exchanger, with corrosion of the fin incontact with the corroding pipe.Photo courtesy of Clearspan StructuresPhoto courtesy of Clearspan StructuresPhoto courtesy of Clearspan StructuresVolume 5 Issue 4 2008 Hot Dip Galvanizing Today 31