Heat Shrink Sleeve Quality Concerns

Heat Shrink Sleeve Inspection Concerns

NOTE:  This is not a product I sell or represent.

     I was contacted this weekend by a customer located somewhere outside of the USA.  They have been installing a heat shrink sleeve system purchased and manufactured in the far east.  Having installed a number of shrink sleeves already, they are finding a number of different things to be highly concerned about.  They asked my opinion:  are their concerns about the heat shrink sleeve issues they are observing valid? 

     I will get into more detail, but the quick answer is:  YES.  This person I'm speaking with is very observant and quite smart.  They are absolutely correct to be concerned about these issues. 

     I shared with them that most every specification that crosses my desk over the course of the last couple of years has a very strict direction in terms of heat shrink sleeve manufacturers:  "No shrink sleeve manufactures from China, Korea or India will be accepted."  This is not my recommendation - this is a policy that I see listed in specifications over and over.  Why is it specified like that?  My guess is that most companies are requiring manufacturers other than those countries because they have tried or evaluated shrink sleeve material from China/Korea/India in the past and they quite simply haven't found the products quality to be at an acceptable level yet. 

     That makes perfect sense to me.  I have evaluated products from those countries a number of times over the years.  They are always looking to break into the US market - and it is very common for me to be offered samples on just about a monthly basis.  I always see the same things when I accept their offers:  adhesives that don't flow or bond well -- and backing that is made from a low density PE and doesn't bring much to the table in the way of strength.  That is a very bad combination!  A shrink sleeve that doesn't stick well -- is not going to protect your pipeline!

     So back to this particular case.  This is a high temp line (80C) and upon inspection after installation - some red flags were raised:

     Here we see some spaces where, upon shrinking of the sleeve, as the sleeve (naturally) begins to longitudinally shrink, the backing pulls back leaving some gaps in the adhesive.  These are areas that might be seen as 'fish eyes' in the two part epoxy world.  In these cases, the backing pulled back and the adhesive had flowed out -- but for some reason, these holes were left behind (there is another lower in the pipe that can be seen). 

     Now, this is does indeed raise a lot of issues - and we are not going to be able to answer them here.  First of all - it is possible this could be an installer issue.  It could be that the PE jacket here wasn't properly cleaned and that what happened there was that dust or dirt was on that little piece of PE and as a result, the adhesive didn't bond to the PE.  That is certainly possible.  It could also be though that this particular adhesive simply isn't flowing very well - and isn't filling properly underneath the sleeve.  If there are gaps here -- what is the step down area going to look like?  What is the weld bead area going to look like?  We can't know - but it could certainly be worth evaluating. 

     Of the 2/3 issues we will look at here - this one might be the most innocuous.  We can't definitively say what is going on - we can't say with 100% confidence that the adhesive has failed here - but we can certainly say 'this is something we would like to look more deeply into'.

     Onto the other issues here (I'll show two photos):

     Here we have two photos / areas that are showing the same problem:  hair line cracking of the adhesive.  This is HIGHLY concerning.  In the bottom picture, those cracks are what I would consider to be:  significant.  I know the top picture is more difficult to see - but those also are very concerning.  My first guess is that these adhesive are just not flexible enough to be used as a pipe coating.  If we see cracks here, where there has really been minimal stress on the pipe - I quite honestly can't imagine the sleeve offering any quality corrosion prevention after even a few weeks of normal and natural pipe movements.  We can clearly see (in the cracks) the beginnings of a leak path.  For all we can tell, the adhesive is also cracked underneath the back.  Not good.  Not good at all. 

     In recent years, there have been a number of shrink sleeve manufacturers pop up.  It isn't difficult to find some cheap labor - and a chemist or two to teach about peroxide bonding.  In addition, in some parts of the world, they try to reverse engineer different adhesives and mastics (this is not a simple task) and quite frankly, they think they copy them well...but they do not.  They then sell a cheap and inexpensive product into different marketplaces around the world (focusing specifically on the Middle East, Africa and Eastern Europe) and they dump a bunch of zero quality pipeline coatings on these jobs. 

     They pitch that they will save you money --- but your pipe is not corrosion protected.  They cost you money.  They cost you lots of money.  It may be a few years but you will have massive corrosion problems and when they are discovered, that Chinese shrink sleeve manufacturer will have changed their name, or gone out of business -- or it will turn out that you were actually dealing with a broker, not a manufacturer - and so the manufacturer is unwilling to stand behind their product because it was the brokers fault (these are all things that I've heard).  

     Raychem (now called Covalence / Seal for Life) - took decades, many PHD's, many chemists -- to perfect that design, creation and consistent manufacture of specialized adhesives and mastics.  Those cannot be reverse engineered.  They can not be copied over the course of a couple of years.  Please do not support the pretenders -- please specify and use only proven products with long successful use histories. 

Heat Shrink Sleeves #1 Field Problem

Q:  What is the most common complaint that comes from a contractor installing Covalence heat shrink sleeves in the field? 

A:  There is no question - it isn't even close.  The one issue that comes up far more than any other question from the field is: "the closure isn't sticking, what do I do?" - sometimes it could be phrased "the closure is dog-earing", "the sleeve won't stick", "the sleeve keeps sticking or lifting up" - and in every case - they are talking about the same thing.  How do I know?  Because everyone and their brother - even on a pipeline crew - now has a camera phone and it is very simple for them to take two seconds out of their day to send me a picture and get real feedback on their issue. I've got my cell phone with me twenty four hours a day.

Here we see the closure strip lifting a bit from the shrink sleeve.  It wasn't heated enough during installation

     Now, let me first explain the purpose of the closure (read more here), the purpose of the closure is to hold the sleeve in the shape of a tube during the installation process.  For hot melt adhesive heat shrink sleeves (like DIRAX, HTLP60 or WPC120) the closures job is finished once that sleeve has cooled.  For mastic coated heat shrink sleeves (like WPCT, WPC65M, WPC100M, etc) the closure does need to stay attached to the pipeline for the life of the line.  So, it is important that when the above occurs....you fix it.  It only takes 10-15 seconds (possibly less). 

     Here is how to fix it:

Re-heating a closure that lifted up after installation

      Step one:  Make sure that the adhesive layer of the shrink sleeve (read here if you're not sure which side of the closure is the adhesive layer) has not gotten dirty, muddy, dusty, etc.  If necessary, wipe it with a rag and some mineral spirits.

     Step two: fire up your torch and lightly heat the closure strip where it has lifted off of the heat shrinkable sleeve. 

     Step three:  Lightly pat the closure back into place with a gloved hand.  You should heat the closure strip until you see the pattern of the fiber reinforcement showing through. 

Voila - this "major field problem" has been solved in less than 15 seconds.