The case of…surprise blistering and rusting on a new tank lining system
From JPCL, July 2012
More items for
Quality Control
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Tagged categories:
Blistering;
Coating failure;
Rust;
Tanks
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Comment from Richard Aguillard, (9/18/2012, 12:31 PM)
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So the liner specification did NOT include substrate cleanliness test, i.e. salt testing prior applying the liner?? And what tank doesn't have a hydro test after construction? It's also a great idea to check the hydro water content for contaminates regardless. And no work should be preformed after liner application without protective coverings and an "after work" final inspection to the liner!
"The presence of water-soluble salts beneath the lining created an osmotic cell" has been rebuked in past research including most recent Myths about Salts,Chlorides, and Coatings. Porous films have no regards to what the substrate consists of. Its only after the water molecule reaches the substrate and have contact with the contaminate that you then have a pressure difference created (depending on the concentration of the then formed solvent and solute=solution).
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Comment from Car F., (9/20/2012, 11:46 AM)
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These are the perennial problems associated with "fast tracking" projects. Probably by now no one is remembring how fast and on time the project was concluded, everyone is looking for someone to pay for the repairs. I'm sure the inspectors are also being asked why do they passed that first test without being physically present ...a series of unfortunate events, most of them preventable.
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Comment from James Johnson, (9/21/2012, 9:23 AM)
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It is amazing that anyone writing such a specification would ignore salts as they are widely known to cause such failures, expecially in tank linings. It is even more amazing that neither contractors nor the inspector did not bring up the matter at pre-bid or pre-work conferences. It is widely known and industry acknowleged that high levels of some salts cause premature failures and that lesser levels detract from overall life spans. There are numerous published articles on the subject and both SSPC and NACE have had committees developing documents on the subject for many years. SSPC has the Guide 15 document providing information on salts testing and NACE has the 6G186 document providing information and guidance on how salts affect coatings and corrosion. Little of this information is new but has been known and discussed for about 20 years, so it amazes me that the subject is ignored when it is the known cause of a huge number of premature coating failures.
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