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Friday, January 8, 2016

Three Layer Field Joint Coating

TLPE Field Joints

     Worldwide, two and three layer polyethylene factory applied coatings are very common.  In the USA, the decision is generally made to use only one layer PE coatings (FBE).  This is a little bit ironic because a normal TLPE factory applied coating is going to use FBE as the primary corrosion coating, then add a layer of an adhesive and then an outer layer of a PE to improve many technical aspects of that coating.  So in a sense, the USA is often using FBE only as a coating, while other parts of the world use FBE + +.   Whatever is decided though, it is always necessary to be aware of the critical nature of the field joints on a pipeline project.  Field conditions are not factory conditions; there is a lot that can go wrong there.  When considering a three layer field joint coating for a field joint (whether that will be used with TLPE factory applied coating or simple FBE coating), HTLP60 is an ideal product for field joint protection of oil and gas pipelines.

raychem htlp
Installed HTLP60 shrink sleeve
           So how does this go in the field?  What is the installation like? 
  1. Pipe of course has to be clean.  Any coating is only as strong as its weakest bond; the bond of mud to steel is not a strong one...
  2. Preheat the steel and adjacent line coating.  The goal here is to get all of it to something in the 140-160F range.  Read this article about our S1301M to find out why this is important.
  3. Mix and apply the S1301M Epoxy.  What is included the S1301M Primer 15 Kit?  A can, B can, mix stick, gloves, applicator pad.
  4. Wrap the sleeve around the still wet epoxy.  No force curing here. 
  5. Secure the closure strip.  The closure forms the sleeve into the shape of a tube during the shrink process.
  6. Shrink the HTLP60 sleeve, using a broad, bushy flamed torch.  You want to shrink circumferentially, around the pipe (two installers for 12" pipe and larger).  
  7. Check for signs of proper install:  no cold spots or dimples; weld profile and factory coating step down visible; adhesive flow at both edges.
     There you have it, fairly simple and a truly superior coating when compared to most of the other options out there.  

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