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Wednesday, December 16, 2015

Offshore Field Joint Coating

Heat Shrink Sleeves for Offshore Field Joint Coating

     Heat shrinkable sleeves have been used successfully on offshore oil and gas pipelines more many, many years.  Whether installed in a J-Lay or an S-Lay, literally hundreds of thousands of heat shrink sleeves are currently preventing corrosion on field joints in the worlds oceans, gulfs and seas.  Heat shrink sleeves have always been a reliable and easy to install option for most offshore project.  Requiring very little specialized equipment, many heat shrink sleeves can be installed on wire brushed (or power brush) pipe surfaces and many heat shrink sleeves can be installed with nothing more than a propane torch and a silicon roller.  With those simple tools and with minimal training, an easily repeatable, consistent, simple; and most importantly:  fast installation -- heat shrink sleeves are very often the most logical choice for offshore field joint coatings of subsea pipelines.

     One of the most commonly used shrink sleeve material types used on offshore pipelines is the WPC100M.  WPC stands for Wraparound Pipe Coating.  The 100M tells us that the sleeve is rated to a temperature of 100C continuous operating temperature and the M tells us that the adhesive sealant of the shrink sleeve is a mastic material (butyl mastic in this case).  WPC100M is a product that can be installed over a wire brushed pipe surface.  WPC100M also requires that the substrate be preheated to a temperature of 212F prior to wrapping and heat shrinking the sleeve.  Residual heat from the welding station can certainly be used as the supply of that preheat temperature as long as the temperature exceeds 212F while staying under 260F (the sleeve would insta-shrink if the backing were exposed to temperatures above its crystalline melt point; which is ~267F).  The sleeve is then torch shrunk in place until it conforms to all substrate surfaces and mastic flow is evident at all edges.  Installation is very quick and we have performed time trials in the past where we installed WPC100M on a 36" pipeline in less than four minutes per field joint using two installers; each with a high output propane torch.

     WPCT is another heat shrink sleeve product that has been used extensively offshore.  Very similar to the WPC100M above, WPCT can be installed over a wire brushed pipe surface.  The preheat temperature for WPCT is in the 140F range.  As you might logically have already concluded; the fact that the preheat temperature for WPCT is lower than the preheat temperature of WPC100M does indeed mean that the approved operating temperature for WPCT is lower than WPC100M.  WPCT is generally approved for use on pipelines operating at or below 104F. 

     Both WPCT and WPC100M are available in a variety of widths less than or equal to 34.25".  Standard options are 11", 17", 24" and 34", but we do have the capability to offer up custom widths for any products that we sell.  In addition, all WPCT and WPC100M sleeves that we sell are offered as /UNI sleeves.  This means that the closure strips are preattached to the shrink sleeve material here in our shop.  This makes the installers jobs even easier and removes the risk of lost closures. 


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