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Monday, November 3, 2014

Heat Shrink Sleeve Installation Time

How Long Does It Take To Install A Shrink Sleeve?

     One of the more common questions I get on a weekly basis:  How long does it take to install a shrink sleeve?  Like just about every other question I get (it seems), the answer is:  it depends.

     Different products generally have different installation procedures.  Sometimes these procedures can be dramatically different from one another.  So for the sake of this discussion, I will only look at our more basic, every day, commonly used products. 

     For those common products (WPCT, WPC100M, DIRAX, HTLP60, etc) - the basic steps of installation are fairly similar.

1.  surface preparation
2.  surface preheat
3.  mix and apply epoxy (only with some product)
4.  wrap the sleeve and secure the closure
5.  shrink the sleeve

1.  Surface prep:  How long does it take to properly prepare the surface of the pipeline prior to installation?  It depends on how dirty it is to start with!  If you have pipe that has been sitting out for months, it is going to be a bit more time consuming to clean than a piece of pipe fresh off of the coating line.  In addition, different sleeves have different requirements with surface prep.  Some sleeves can be installed over a wire brushed pipe surface.  Some must be installed on a sand blasted pipe surface (other two part products can require a very specific anchor pattern).  In addition, pipe size will have an effect.  More square footage to clean = more time cleaning.  Pretty simple.

2.  Surface Preheat: This varies as well depending on the type of adhesive being installed.  Different adhesives require different preheat temperatures in order to properly install the product.  To keep it simple - different adhesives require that different bond line temperatures be reached in order to insure that the sleeve is going to perform as advertised.  Sometimes, this might be 'hand hot' (~140F).  Other times it could be as high as 440F.  Beyond that though, there are other factors that can influence time required to preheat the steel.  What is the pipe wall thickness?  Heavier wall pipe will naturally require more time to heat.  What are the ambient temperatures?  If you're trying to preheat the pipe during a howling snow storm, it is likely going to take longer than if you're trying to preheat the pipe on a calm summer afternoon in Texas.

3.  Mix and Apply Epoxy: Some products utilize a two part epoxy to both improve some physical characteristics of the shrink sleeve system (generally improved cathodic disbondment, improved peel).  In addition, the epoxy can take the place of a higher preheat temperature requirement, so it can save time on that front as well.

4.  Wrap the sleeve, secure the closure:  This step takes about 20 seconds no matter which product you are using.

5.  Shrink the sleeve.  This one can vary.  Of course pipe size will make a large difference, as will torch output.  I can share though that we have conducted time trials in the past to gauge the install time of a WPC100M shrink sleeve on a 36" pipe.  With high output torches, we were consistently preheating, wrapping and securing the closure and shrink the sleeve in less than 4 minutes.  That is with two experienced installers working together.

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