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Posted by Arjun Sen Therefore, should you use "sand blasting" or any other abrasive media for blasting? If the answer is any other, what would be those media? Secondly, what should be the anchor profile to be created from blast operations? Obviously, anchor profile requirements will differ between liquid and powder coatings for the simple reason that each of the above coating types have different maximum dfts. Would sand blasting provide the desired anchor profile? If so, what is this anchor profile? And finally, what are the acceptable standards for surface preparation prevelant in India as well as worldwide for surface preparation on exterior of steel pipes? Best wishes, A. SEN.
on 8/16/2002, 11:12 am
Sand blasting on steel or on any other substrate will leave chloride ions on the substrate and inside the profiles created during blast operations. These retained chloride ions cannot be washed off from blast cleaned steel. Traces of chloride ions would become detrimental to coating performance. Use of coatings on steel or on any other substrate is primarily to protect the substrate by stopping or at least slowing the ingress of ions like chlorides & sulphates. Why should one, therefore knowingly use a blasting media that will leave on the substrate the very ions that the coating is trying to stop from attacking the substrate? This will be true whether you use liquid or powder coatings.
Consultant, Protective & Functional Coatings
Bombay, INDIA.
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