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Monday, October 24, 2016

Cold Weather Pipe Coating

Installing Pipe Coating in Cold Weather

     Choosing and installing a proven field joint coating can be a tough job.  There is an incredible amount of bad information out there as competing technologies focus more on bashing other products than they do on explaining the strengths of their own products.  It isn't much unlike the current political state in the US!  But as hard as it can be - when winter rolls around and we are faced with cold months; that introduces an entirely new set of challenges and obstacles to attempt to overcome.

     What are the challenges that cold weather can bring to the field joint coating process?
  • Cold pipe is generally not very conducive to accepting a bond.  Pipe must be preheated up to a warmer temp (varying by product) in order to properly bond.  When it is very cold out - this becomes more difficult depending on what your preheat method is.  
  • Cold temps often bring with them cold winds.  This works to quickly cool pipe even if it has been preheated.  Pipe must be brought to temp -- and kept at temp throughout the install.  
  • Cold temps have a significant impact on products that require a cure time.  That 3 hours cure can become 75 hours in some cases.  In some cases (under 40F as stated on some data sheets) curing absolutely will not occur. 
     So what is the solution when you are building a pipeline during seasons where temperatures are simply colder during certain months?  You have to plan for it.  Depending on your coating of choice, you may need to make sure your contractor is able to construct shelters and moveable buildings in order to protect the pipeline.  You also need to plan for how you are going to keep steel temps up during that process - it could be something as expensive as inductive heating coils or it could be something as simple as using propane torches.  It is your pipeline, so the choice is yours!

      As for me, when I get that call from someone in the field working on a pipeline spread where temperatures are very cold; I normally recommend installing a heat shrink sleeve there.  The cold temperature will be less of a factor.  Though there are many options - the first two I would look at would be:

HTLP60 - rated for use on pipelines operating at up to 60C.  A three layer coating system for the field joint incorporating a two part epoxy; a hot melt adhesive and a PE backing for physical protection.  You might be asking yourself  "wait - you're looking at an epoxy component, but the temps are cold.  How is that going to work??"  I'm glad you asked.  We preheat the steel to 140F - then we wrap and shrink the sleeve (sleeve backing shrinks at 267F).  The heat from the preheat and install is sufficient to cure all epoxy; regardless of the outside ambient temps.

DIRAX - the premier product for road bores and directional drilling applications.  Similar to the HTLP60 - it incorporates a two part epoxy, a hot melt adhesive, a fiber reinforced backing all to create an incredibly tough coating system.

In both cases , the coating system incorporates all of the strengths and advantages of a two part epoxy - without being excluded from cold weather applications.  It is a fantastic marriage of coating technologies that provide an excellent a proven field joint coating.

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