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Thursday, August 22, 2013

Recoating an Active Pipeline

     The task of recoating an active pipeline is always a very, very difficult one.  Sometimes the pipeline might be operating at a lower temperature (50F) which essentially eliminates most stand along liquid epoxies as options.  Other times; the pipe might be actively sweating which eliminates just about every possible coating.  Because the pipeline is active; the product inside of it acts as a tremendous heat sink; making pipe preheat essentially impossible.  It is very, very complicated. 

     One solution that we've offered over the years is to utilize a three layer heat shrink sleeve system.  In such a system; a liquid epoxy is used as the bonding agent between the shrink sleeve and the pipe.  This liquid epoxy acts as a replacement for 'preheating' the steel (since preheat is impossible on an active line).  Because the pipeline is cool; the epoxy typically goes on in a VERY thick coat (much like honey).  The sleeve is then wrapped around the wet, uncured epoxy and shrunk in place.  The heat that is generated from the propane torch while shrinking the heat shrink sleeve (which shrinks at ~270F) goes a great ways toward helping the liquid epoxy to properly cure.

     In such a system, you end up with the strengths of a liquid epoxy and the strengths of a high density PE shrink sleeve all in the same shrink sleeve system.  This sort of system can be used for coating girth welds; for completing coating repairs; or for coating long lengths of pipe.  In just about every instance, we would be recommending our S1301M liquid epoxy to be used with a suitable heat shrink sleeve (could be WPCT, HTLP60, WPC100M, HTLP80 or others). 


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