Why Not Use DIRAX Shrink Sleeves for Every Field Joint?

As has been mentioned before when I addressed the common question:  What is the toughest shrink sleeve?

DIRAX is without a doubt the toughest shrink sleeve on the market.  It uses our S1301M primer to act as the bonding agent between the steel (and FBE) and the DIRAX shrink sleeve.  This S1301M epoxy also acts as the primary corrosion coating.  During the bore (and after) the DIRAX sleeve and leader strip offer unparalleled physical protection to that epoxy in the form of high shear hot melt adhesive layers; PE layers and fiber mesh layers.  All in all; that epoxy is PROTECTED.  Nothing is getting in there. 

Here we see a DIRAX (ROCS) shrink sleeve being installed on a TLPE coated pipeline.

I've seen it time and time again (DIRAX has a long use history that is unmatched by anything else in the industry). 2" pipe:  no problem.  4" pipe:  no problem (backward and forward and oh, by the way, the cold applied tape disappeared somewhere down in the hole as seen in this DIRAX case study).

So, why not USE DIRAX on every single joint; rather than just the road bore sections of your pipe?  Well, the truth is, it just isn't necessary in my opinion.  If a customer insisted on the best field joint coating, regardless of the cost, I would gladly offer them DIRAX (though without the leader strip, it is called the ROCS shrink sleeve).

But in this practical world in which we live, products like WPCT, WPC100M, HTLP60 and TPS (just to name a few) are all VERY good at doing exactly what they are supposed to do...sealing that field joint and preventing any water or air from getting to the bare steel.  

Best Field Joint Coating

     The  we live in focuses primarily on a single thing.  What is the cheapest and easiest thing that I can use?  It isn't always the case; and I am certainly being a bit unfair by saying that - but it is something I've seen again and again and again  in the last 13 years (my time in the pipeline world).  For many decision makers; cost is all that matters: "buy whatever is cheapest...it's all the same." 

All Field Joint Coatings AREN'T Created Equally

     So, when I do get the comment "I want whatever the best coating is - this pipeline is too valuable to scrimp on the field joint coatings" I tend to sit up and take notice.  Here is a person who cares about the future of this pipeline.  Here is a person who is committed to doing their best job possible; even if they are no longer with this company through the life of the line.  Here is a person with integrity.  Here is a person who cares about the long-term...not just about moving on to the next project or claiming that next promotion.

     In cases like this, where the request is for the "best" AND where we don't have an issue with elevated operating temperatures; the answer is clear.  The best possible field joint coating is ROCS.

The ROCS heat shrink sleeve system is absolutely unmatched in the coatings world.

     What you see here is a picture of the ROCS shrink sleeve.  The pattern you see is the fiber mesh (which is woven between two layers of HDPE, heat shrinkable backing.  The other side of this sleeve is a high shear adhesive.  All of this is installed on Covalence's S1301M liquid epoxy which chemically bonds with the adhesive of the ROCS shrink sleeve in order to form a truly cohesive field joint coating.

     Since the ROCS shrink sleeve system utilizes both a heat shrinkable sleeve and a liquid epoxy bonding agent; it literally offers the best of both worlds.  The liquid epoxy gives the coating system superior cathodic disbondment properties and sheer resistance.  The fiber reinforced shrink sleeve gives the coating system excellent electrical resistivity properties; superior abrasion resistance and fantastic penetration resistance. 

     Like all things in life; you get what you pay for.  The ROCS field joint coating system is expensive on the front end, during construction.  But the truth of the matter is that leaks, repairs and corrosion problems are incredibly expensive.  Taking a line out of service can cost almost a million dollars per day (as seen here).  There must be a point where 'cost' is not the number one factor when selecting a field joint coating; are we there yet?

What is the Widest Shrink Sleeve?

What is the Widest Shrink Sleeve for Pipeline Use?

Here we see the different shrink sleeve widths available:  11", 17", 24" and 34"

    It is a fairly common question I get:  What is the widest shrink sleeve you have?  On the pipeline side, the answer is pretty much always 34" (on the electrical side - the answer is almost limitless as there are many products sold in tubular form as rolls which can be 50 or more feet long).  Now, why do people ask that question?  It varies.

     In a case where someone needs to coat a long length of pipe (or at least a length longer than a few feet) they want the widest shrink sleeve because they want to install fewer sleeves.  In a case like that; 34" wide sleeves work very well (as illustrated here in our lobster tailing video):

     In other cases, perhaps someone wants to have as much overlap as is possible to give their field joint coating the 'safest' possible application.  To put some numbers to it; the cutback on a standard field joint of FBE coated pipe will likely have only 3 or so inches of bare steel.  If someone installs a 34" wide sleeve on that field joint; they will end up with as much as 15" of overlap onto the adjacent factory applied FBE.  Wow, that is a lot of overlap!  It would certainly be difficult to imagine water somehow working its way through 15" of installed shrink sleeve!  Is that overkill?  In my opinion, it is certainly unnecessary.

     Finally, I see cases where an end user or a contractor has contacted a supply house looking for shrink sleeve.  In some of those cases (rare, I promise!) that supply house isn't able (or willing) to determine what the cutbacks, factory applied coatings, etc are for a pipeline project.  In order to keep things as simple as they can, they ask me "what is the widest sleeve you've got?  Give me that one".  Not a good plan, in my opinion, but I do at least understand the mind set - "better safe than sorry".

    Calculating what width of a shrink sleeve your pipeline needs is a lot easier than you might think.