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Monday, June 24, 2013

Heat Shrink Sleeves #1 Field Problem

Q:  What is the most common complaint that comes from a contractor installing Covalence heat shrink sleeves in the field? 

A:  There is no question - it isn't even close.  The one issue that comes up far more than any other question from the field is: "the closure isn't sticking, what do I do?" - sometimes it could be phrased "the closure is dog-earing", "the sleeve won't stick", "the sleeve keeps sticking or lifting up" - and in every case - they are talking about the same thing.  How do I know?  Because everyone and their brother - even on a pipeline crew - now has a camera phone and it is very simple for them to take two seconds out of their day to send me a picture and get real feedback on their issue. I've got my cell phone with me twenty four hours a day.
shrink sleeve lifting up
Here we see the closure strip lifting a bit from the shrink sleeve.  It wasn't heated enough during installation
     Now, let me first explain the purpose of the closure (read more here), the purpose of the closure is to hold the sleeve in the shape of a tube during the installation process.  For hot melt adhesive heat shrink sleeves (like DIRAX, HTLP60 or WPC120) the closures job is finished once that sleeve has cooled.  For mastic coated heat shrink sleeves (like WPCT, WPC65M, WPC100M, etc) the closure does need to stay attached to the pipeline for the life of the line.  So, it is important that when the above fix it.  It only takes 10-15 seconds (possibly less). 

     Here is how to fix it:
heat shrinkable sleeve
Re-heating a closure that lifted up after installation
      Step one:  Make sure that the adhesive layer of the shrink sleeve (read here if you're not sure which side of the closure is the adhesive layer) has not gotten dirty, muddy, dusty, etc.  If necessary, wipe it with a rag and some mineral spirits.

     Step two: fire up your torch and lightly heat the closure strip where it has lifted off of the heat shrinkable sleeve. 

     Step three:  Lightly pat the closure back into place with a gloved hand.  You should heat the closure strip until you see the pattern of the fiber reinforcement showing through. 
Covalence WPCT
Voila - this "major field problem" has been solved in less than 15 seconds.

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