DIRAX Field joint Coatings

DIRAX Road Bore Coating

     Road bores and directional drilling applications put incredible stresses on pipeline coatings.  That is one reason that a main line abrasion resistant overcoat like Powercrete has been so popular over the years.  That is also one of the major reasons that dual layer FBE's and other ARO's have been developed, specified, sold and applied.  Product selection becomes a little bit more difficult when considering field joint coatings.  One of the main reasons this is the case is that field applications are dramatically different than coating plant (or lab) applications.  Crews aren't trained as well.  The environment isn't as controlled.  Nothing is stream lined in the field.  That is where the DIRAX product really shines.  Because of its simple installation, DIRAX installation is easy and consistent.  Two incredibly important features in a field applied coating.

     So, what are the steps of DIRAX installation in the field that make it so easily repeatable and consistent?  I'm glad you asked. 

1. Surface preparation; while important; is not as critical as it is in a factory setting.  The anchor patterns required for many two part epoxies and fusion bond epoxy are not major factors with DIRAX.  Like any coating, of course the substrate needs to be clean (the cleaner the better) but anchor pattern are not a requirement.  Surface prep to SA 2 1/2 (and even wire brush in some cases) is all that is required.
2. Epoxy thickness is fast and easy.  No more headaches trying to get a proper uniform epoxy thickness all the way around the pipe.  No more issues with an epoxy coating that is too thin on top and too thick on bottom with icicles and drips forming.  The DIRAX coating system utilizes our S1301M Epoxy as a bonding agent between the high shear adhesive of the DIRAX and the pipe surface (including factory applied coating).  The S1301M also acts as a coating enhancement; improving shear, peel, CD and other critical coating characteristics.  The S1301M is applied in a very thin layer; only microns thick and the coating integrity is not hinged upon a certain 30+ mil coating thickness in order to corrosion protect properly.  
3. No real skill required.  There is no requirement for skill by the installer.  Their skill is not going to determine coating thickness.  Installer skill is not going to impact holidays or fish eyes or icicles.  The installers simply wrap the DIRAX sleeve around the still wet S1301M epoxy -- the DIRAX sleeve itself is designed to shrink 25%; so there isn't even any skill in wrapping the sleeve.  Wrap it snug?  That's fine.  Wrap it with a 1/2 inch bag?  Fine.  1 inch bag?  Also probably fine (depending on your pipe size).  After that you're simply shrinking the sleeve in a circumferential pattern starting on one end and moving toward the other.  
4. Virtually no cure time.  No need wait multiple hours.  No risk of the crew pulling that pipe too soon (before the joint coating is cured) and ruining the coating.  No risk of someone bumping up against the pipe and creating holidays in the uncured epoxy.  The thinness of our epoxy, plus the heat of the steel preheat, plus the heat of the torch during the shrink process --- all leads to a fully cured coating system that is almost always ready to see stresses within just a few minutes after installation is concluded.  
5. Minimal installation time is also a big factor here.  Ignoring surface prep (which will vary based on how dirty your pipeline is) - you are looking at just a few minutes per field joint of coating time.  This saves you labor costs.  Preheating the steel to 140F is very quick (will vary based on pipe size).  Mixing and applying the epoxy is only a minute or so.  Wrapping and shrinking the DIRAX sleeve and the Leader Strip is also very fast (I've installed sleeves on a 36" pipeline in only three minutes before).  

WPCT for Road Bores?

Standard Shrink Sleeves on Road Bore Applications

     The world of pipeline coatings is much like the world of tools. Different tools are designed for different functions.  Brooms are great, and very effective when sweeping up dirt....but they are going to be pretty much useless if you're trying to cut down a tree.  Likewise an axe is great for cutting down a tree, but is not going to be particularly effective for tightening a bolt.  A wrench can tighten a bolt great, but it isn't going to be very effective if you're trying to dig a deep hole.  Likewise; standard shrink sleeves are great for basic, drop the pipe in a ditch and backfill it types of applications; but they are quite simply:  not designed for use in road bore applications. 

     WPCT is our most commonly sold ambient temperature, wrap around, heat shrink sleeve for corrosion prevention.  It is a fantastic product.  It has successfully prevented corrosion for decades on literally millions of field joints over the last decade.  It is easy to install.  It is reliable.  It essentially inspects itself.  But WPCT is not approved or recommended for use on road bore applications.  That simply isn't what it is designed for. 

     The product that is specifically designed for road bore service is our DIRAX product.  Incredible peel and shear resistance.  Unparalleled abrasion resistance and penetration resistance.  This sleeve is three times thicker than the WPCT product (on the leading edge of the coating).  DIRAX uses a two part epoxy as the primary corrosion coating.  That two part epoxy brings with it excellent cathodic disbondment resistance and improves the physical characteristics of the system (better peel / shear).  The DIRAX sleeve is then installed over the wet epoxy.  DIRAX is comprised of a three layer backing system and a high shear polyamide adhesive; which is designed to physically and chemically bond to the two part epoxy; forging a contiguous, bonded, thick field joint coating system that will easily withstand any forces it is put through during the boring process. 

     To sum up:

DIRAX for directional drilling:  GOOD

WPCT for directional drilling:  Not Good

    
     Now, there are folks out in the world who will tell you that "WPCT will do just fine on a road bore."  Please, do not believe those folks.  They are just looking to make a quick and easy sale.  They aren't evil people, they are simply uneducated.  They want things quick and easy rather than spending the time to learn the ins and the outs of the Covalence heat shrinkable products product line. 

World's Longest Directional Drill

Field Joint Coating for Long Directional Drill

*I have two sources for this article.  One is Stan Simpson who was involved in this project back in 1999 / 2000.  The second is an article written and published in Pipeline & Gas Journal in April 2000. 

 

     Though directional drilling applications have seemingly gotten more and more complicated as the recent decade or two have passed (including bundled directional drills with as many as four pipelines travelling through the whole at once) it is almost hard to believe that 14 years ago, BP and Mustang Engineering undertook a directional drilling project that was (to that point) unheard of:  a 5.4 mile long section of pipe directionally drilled underneath Lavaca Bay! 

 

     As if that wasn't enough of a head ache, they also had to deal with the fact that Lavaca Bay was a federal Environmental Protection Agency environmentally sensitive superfund site involving mercury containing sediments.  The longest directional drill?  Through a section of bay already being watched by the government?  There was going to be no room for error on the field joint coatings for this project...

     So what did they decide to use?  Yes: DIRAX.  The thickness, penetration resistance, peel, abrasion resistance, and shear of the DIRAX shrink sleeve system is simply unmatched in the industry.  Dirax utilizes a high shear, two part epoxy as the primary corrosion coating on the field joint.  A shrink sleeve is then installed on top of that epoxy and as the sleeve is installed, the epoxy and the adhesive of the sleeve become physically and chemically bonded. That Dirax sleeve isn't going anywhere - and with hundreds of thousands of field joints coated with Dirax and pulled through bore holes; we've yet to hear of a single case where the Dirax failed.  Not even one.

     Dirax did a fantastic job on this project and hundreds of other before and since.  If you don't have Dirax approved on your next project....why not?  Let's talk. 

Road Bore Field Joint Coating with Fastest Cure Time

Which road bore pipeline coating has the fastest cure time?

    When considering cure times, there are a number of factors (which are often uncontrollable) that affect cure times.  These include humidity levels, ambient temperatures, substrate temperature and design parameters of the curing material itself.  If you are in the field, or if you are writing a specification for a pipeline project - it won't take you long to realize that you cannot control any of those factors! 

     As a result, the only way you can influence installation and cure times is by focusing on what you can control:  product selection.  If you're selecting a curable material to coat the field joints (girth welds) on your pipeline which will be involved in a road bore or directional drill; I'm guessing you already understand that extreme conditions through which you are going to put that pipe.  I'm assuming you're also aware that once it enters the hole; the pipeline is never going to be seen again.  You're going to have one shot to get that pipe properly coated and that is it.  Add in the requirement that you need a fast curing material and you might have real problems on your hand.....or will you?

     Looking through published data of one of the leaders in the two part epoxy pipeline coating business, it is very easy to determine the manufacturer predicted cure times.  Of course, they vary based on the temperature of the substrate and (mostly) the temperature of the Earth at the time and place that coating is occurring.  It is my understanding that 'force curing' most stand alone two part epoxies is a bit sketchy.  But in any case, right here in the data of "one of the fastest curing epoxies" I can see that if the temperature outside if 60 degrees F; the epoxy will need 6-9 hours before it hits its reported Shore D value of 80-85. 

     If the outside temperature is 80F, you are looking at 3-4 hours before reaching Shore D hardness of 80-85.  If it is 90F outside, that number drops to 2-3 hours.  Still a long time if you're dealing with a road bore and a limited right of way for stringing up pipe.  Another interesting fact though:  at that 90F - the epoxy doesn't reach "tack free" until 30-40 minutes have passed.  That can mean 30-40 minutes of working, reworking and re-reworking the epoxy to minimize drips, icicles and coating inconsistencies.  Tough challenge.

     So, say you are a fan of many of the physical properties of two part epoxies.  You like good cathodic disbondment.  You like the improved abrasion resistance, shear, peel, etc.  But, you can't live with the cure times.  Well I have good news for you.  Our DIRAX product utilizes a two part epoxy as the primary corrosion coating of the system (use history).  Over that, the DIRAX system offers unparalleled protection for your field joint.  Even better though is the cure time.  Since the epoxy in this scenario is not a stand alone epoxy...the option to force cure it becomes technically sound.  Given that you're preheating the pipe surface to 140F -- and then the DIRAX is contracting at 260F -- there is plenty of heat getting into that epoxy so that this system is installed in 7 minutes or less (for typical pipe sizes) and completely cured and ready to pull within about 30 minutes (ready for pull as soon as installation is completed and cooled back to ambient temperatures which could include a quench of some kind).

     So - several hours and lots of labor....or thirty minutes and minimal labor.  I don't think its close -- especially when you're dealing with a right of way issue.
 

Pipeline Coating for a River Bore

River Bore Pipeline Coating

      In the pipeline world it is a fairly common occurrence that a pipeline be bored underneath a river; just like it is common for pipelines to in a directional bore under a road, a directional bore under a railroad, a directional bore under a lake, a directional bore under a bay or sometimes even a directional bore under land that could not be torn up due to right of way or environmentalist reasons.

 

     Isn't that a beautiful sight?  Boring a pipeline underneath a river like this is going to raise ALL KINDS of questions.  Some very fair.  Some not fair.  It will politics as usual, that you can be certain of.  One of the concerns with a directional drilling project is that once the pipeline goes down into the wet, black hole....no one is EVER going to see it again!  No one is going to be able to inspect the pipeline to be certain the pipeline coating you've selected is still in place and functioning properly.  In some cases it will even be difficult to be certain that your cathodic protection system is going to be able to properly protect your pipeline if there was any damage during the pull through.

 

     Beyond that, if there is some kind of pipeline catastrophe, where will all of the product from the pipeline go?  There will certainly be no way to repair a pipeline -- replacing the line will be the only option and that is incredibly expensive.  In light of all of that, obviously, the external pipeline coating selection for this section of the pipeline is incredibly important.

 

     For the main line coating, here in the USA it is generally accepted that the best coating option is going to be either a dual layer FBE (with the outer layer having more ARO qualities) or an FBE with a Powercrete type ARO (abrasion resistant overcoat) installed over the outside of it.  For the field joint coating, there are more schools of thought.

 

     Believe it or not, I live in The Woodlands, TX.  A wonderful community just north of Houston, TX.  It is a booming part of the state with people moving in by the droves.  Many large corporations are also in the middle of moving their bases of operations to this area.  Given all of that, you would think we might be on the cutting edge of technologies when it comes to the pipelines that are constructed in our neighborhoods.  You would be wrong!

 

     Just two years ago, I saw a bore underneath one of our largest creeks.  Right next to this creek where the bore took place sat a bridge that sees heavy traffic just about all day long.  Whoever owned/worked on that pipeline chose to put a cold applied tape on the field joints of the road bore section of the pipeline!  (Are you wondering what happens to cold applied tape during a road bore?  Read and find out).  This was a unique situation for us as we had a good contact with that very tape manufacturer.  He was horrified that his product was used on a road bore in a heavily populated area underneath a bridge and a creek.  Horrified.  So horrified in fact that he went in with us to visit with a couple of engineers and tell them that they had made (and had been making) a terrible mistake by using his product for that purpose.  Amazingly, they either didn't care -- or were uninterested in getting involved.  I drive over that bridge twice a day (once with my children in the car with me) and I am absolutely certain that those field joints are now bare.  I sure hope the CP system is working because that is all they've got. 

 

     Likewise, near my neighborhood there is a section of pipe that has been welded and coated and lying in the dirt next to the golf course for weeks!  It might even be months.  Just driving by there I can see that the cold applied tape is bubbling up in some spots; peeling back in some spots and getting disfigured already from the weight of the pipe.  I can see it going by at 40 miles per hour!  Why has the pipe been sitting so long?  Well it looks like they are waiting for the boring equipment to come out so they can pull it underneath a different creek! 

 

     There is always the option of bringing out flocking equipment and applying dual layer FBE in the field, but given the cost of the equipment that often doesn't make a lot of sense (since bores tend to be somewhat short in length).  Another option is to apply a two part epoxy like Powercrete or Protal.  Those are good options and they have been quite successful as long as the surface preparation is done properly, the crews are experienced and the job allows for a longer cure time. 

 

     In my world though, the absolute best solution for any critical service field joint (like underneath a river) is to use the DIRAX shrink sleeve system.  It has been proven again and again and again.  Cure times are down under thirty minutes.  Install times are down under 6 minutes (depending on pipe size).  Heck, it has even been used to hold bumpers in place during a bundled directional drill.  If this product can prevent pipes in a bundle from banging against each other while passing through a bore - and it doesn't move - and it doesn't disappear - and it isn't damaged - just imagine how much less taxing simply coating a field joint is!  Read about a recent BBS success here.

5 Signs You Might Need DIRAX

5 Signs That You Need DIRAX Shrink Sleeves

1. The pipe you're working with (or selling) is coated with Dual Layer FBE.  Dual Layer FBE is very often used on pipe that will be involved in a road bore or a directional drill.
2. The pipe you're working with or selling is coated with Powercrete or an ARO (abrasion resistant overcoat).  This will almost always mean that the pipe is going to be part of a road bore or directional drill.
3. You heard mention of "road bore", "directional drill", "directional crossing", "beach pull", "river crossing", "thrust bore" or "push bore".
4. You hear mention of "epoxy sleeves", "wear cone", "leader strip", "leading strip", "fiberglass sleeves" or "thrust bore kits".
5. You have an application where you know the pipeline coating will be required to withstand extreme forces, extreme soil stresses or significant abrasion and/or penetration forces.