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.

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.  

HTLP60 Shrink Sleeves

HTLP60 Shrink Sleeve Coating Handout



Cover of a Raychem Handout circa 1985 - HTLP60

     This is the cover of a Raychem HTLP60 shrink sleeve hand out made and in use in 1985.  Personally, I'm not really sure how coating your pipeline with HTLP60 (a great product) is "keeping an eagle eye on your pipeline"; but maybe this supposed to appeal to the US market.  You know how much we Americans love our eagles....how could we turn down any product that uses an eagle as the focal point??

 

     The beautiful thing is that this product has been in use for more than 20 years now, and it been exactly as dependable as it was presented to be back in the 1980's.  Wait, that's probably not actually true.  I would argue that this sleeve has exceeded any expectations.  Back in the "old days" 20 years was often a number thrown around as the life of a pipeline.  As a result, many coatings manufacturers sought to meet that same 20 year life expectancy with their coatings.  Here we are way more than 20 years from the inception and installation of many of our products - and those coatings are still going strong, performing exactly as expected. 

 

     Inside of this hand out you can find the following text:

 

     The HTLP60 system consists of an active modified epoxy primer and a specially coated heat-shrinkable sleeve.  Resulting in a 3-layer anti-corrosion coating with all the virtues of combined epoxy / cross-linked Polyethylene systems, improved impact, adhesion, high temperature and cathodic disbanding performance.  Fully compatible with Fusion Bond Epoxy or Polyethylene line coatings. 

 

     In order to achieve adequate adhesion to steel high performance field joints have in the past required high steel preheat temperatures.  A time consuming, critical and expensive on site operation.  HTLP completely eliminates this preheat. 

 

    To Install HTLP simply:

1. Sand blast girth weld area.
2. Flame brush steel to remove moisture
3. Apply active primer to steel and adjacent FBE
4. Shrink sleeve using a standard propane torch

     Contractor Advantages:

1. No induction heaters
2. No special tools or spray equipment
3. No refrigerated storage needed
4. No high preheat hence no potential main coating damage
5. No critical surface preparation required (anchor pattern)
6. Field friendly
7. Low manpower requirements
8. Does not require highly skilled installers
9. Allows tie ins and weld skips to be done with ease
10. Any number of joints crews can install
11. Lower installed cost

     Pipeline owners and contractors need to keep a sharp eye on corrosion and construction costs.  Not surprisingly therefore Fusion Bonded Epoxy and Polyethylene are increasingly becoming the industry's coating choice.  To complete the on site girth weld area protection of these quality coatings, Raychem has created a unique system, HTLP.