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Monday, September 12, 2016

HTLP60 - Three Layer PE Field Joint Coating

HTLP60 - Raychem Field Joint Coating

     In the world of pipeline field joint coatings, there are a lot of options out there.  With several coating technologies to choose from and many different specific products within those technologies, there is really an awful lot to learn.  I suppose that is why NACE offers so many classes and opportunities for learning!  Allow me to give an incredibly brief and horribly insufficient summary of a few of those options below.  

Cold Applied Tapes - A cold applied, spiral wrapped two layer tape.  Sometimes installed over a mastic primer.  Has been used extensively since the 1970's.  An interesting technology - with an incredibly long use history; there are certainly applications where a cold applied tape would be a terrible choice...but there are also applications that are very well suited to it.  Still used frequently today.  In the world of pipeline coatings; end users must sometimes ask themselves the very practical question:  which coating is good enough?  Some do decide that cold applied tapes are 'good enough' in spite of their general coating weaknesses.  

Two Layer Shrink Sleeves - Simple, repeatable installation.  Products for a wide range of pipeline operating conditions including hot lines, ambient lines; onshore lines and offshore pipelines.  Installed without any special training or skills required using a simple propane torch.  Can be installed on wire brushed surfaces (in some cases).  Built in inspection tools make the inspector's job very easy.  Proven with decades of successful installations. 

Two Part Epoxies - Several major manufacturers out there.  Installation is slightly more labor intensive and does require some minor skill.  Anchor patterns in the bare steel are required.  Installer skill will determine whether a uniform thickness of epoxy is achieved or not.  Excellent cathodic disbondment resistance.  Very good adhesion to the steel and the FBE when installed with proper surface prep. 

Multi Layer Shrink Sleeves - Here we have multi layer shrink sleeve systems.  A couple of examples would be HTLP60 or DIRAX.  In both cases, a two part epoxy is used in conjunction with a hot melt adhesive and a strong heat shrinkable backing to create a coating system that pulls together all of the strengths of a two part epoxy and combines them with all the strengths of a heat shrinkable system.  You get the best of both words here.  As the epoxy cures and the shrink sleeve and adhesive cool; you are left with a cohesive three (to five) layer coating system that will offer unparalleled corrosion prevention for decades to come. 

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