Simple Repair for minor PE Pipe Coatings

 Perp Melt Sticks - Easy Repair for PE Pipe Coating

A Perp Melt Stick in Action

     Perp Melt Sticks are heat sensitive, polyethylene copolymer sticks used for small superficial damage to PE coatings where the damage does not extend to the bare metal.  Generally speaking, installation of Perp Melt Sticks is done with a standard gas torch.  After eliminating all sharp edges, cleaning and preheating, the Perp Melt Stick is heated above the damaged area until becoming glossy (beginning to melt).  The flowing adhesive is then spread onto the scratches, forming a tight bond with the PE substrate.  After it cools down, the hardening, cooling adhesive is smoothed flush with the PE line coating using a paint scraper of some kind. 

    Perp Melt Sticks are high economical and versatile.  The adhesive also shows resistance to high shear forces and excellent adhesion to commercial PE mill applied coatings.  They can be used on pipelines operating at up to 80C (176F).

1.  Remove loose coating from the damaged area with a knife, scraper or wire brush.  Eliminate all sharp edges and clean the damaged area and adjacent coating to remove all foreign materials such as dirt, rust, oil, grease and moisture.

2. Preheat the pipe coating to 60C.

3.  Heat the end of the Perp Melt Stick until it becomes glossy.

4.  Spread the molten adhesive onto the damaged area.  

5.  When the PE is hard, smooth the molten adhesive flush with the PE line coating by use of a point scraper.

S-1137 Perp Filler

 S1137 Perp Filler 3x50x3000

S-1137 Perp Mastic Filler

    S-1137 Perp Filler is a mastic filler material that is often used in conjunction with PERP (Poly Ethylene Repair Patch) in order to repair damage to PE pipe coatings.  It can be used for other things as well:  filling irregular pipe surface, adding depth to a step down area to be certain there is no void left under a coating, etc etc.

     Most commonly sold in dimensions that are 2" wide, 1/8" thick and 10 feet long - S1137 can be used in pretty much any situation that requires a mastic filler material. . With a typical softening point if 150C, Perp Filler can really do an awful lot.  

How Do You Repair Damage to a Shrink Sleeve?

Repairing Damage to a Shrink Sleeve

A shrink sleeve during installation process

     So first things first, it is incredibly rare in my experience that a shrink sleeve is damaged.  In my 24 years being heavily involved with shrink sleeve sales, specifications, training and product recommendations I've sold more than a million shrink sleeves (so a million field joints coated).  Here are the reasons I've been told that damage occurred (spoiler alert:  there aren't many):

1. A truck backed into the pipe and struck the field joint; tearing the sleeve.
2. An installer was checking his phone while the torch (with no regulator) burned a hole clean through the sleeve.
3. A disgruntled worker vandalized some sleeves that had been installed the previous day.
4. The installer tried to install using a rosebud torch instead of a propane torch (with a regulator set to provide a large, bushy, yellow flame).
5. A backhoe accidentally brushed against the shrink sleeve.
6. The installer didn't think the sleeve was the right size, so he trimmed it down himself resulting in there being no sleeve overlap onto itself -- and the sleeve not being wide enough to overlap onto the adjacent factory applied coating by the required 2-3 inch minimum.

     That's it.  As you may notice, every one of those reasons can be classified as an installation error.  The Covalence plant in Mexico does an incredible job making sure that every roll of sleeve material that they ship has been inspected and passed all QA/QC requirements.  They have been doing this a very long time and they are GOOD at it.  The simple fact is:  sleeves are very rarely damaged.

     BUT -- if you do have a damaged sleeve - see below for the bare basics....BUT -- I think it would be better if you gave me a call and we can discuss it (936/321-3333).  It can also be helpful if you send me a photo of the damaged area in advance, so we can be certain we are both on the same page (photos can be emailed to:  steve@jsicoatings.com).

SIGNIFICANT DAMAGE

     For the sake of this ridiculously brief overview; I'm considering "significant damage" to be any damaged area larger than a 3" square.  This could be a 'gash' in the sleeve backing; or this could be a scrape through the sleeve exposing bare steel.  In many cases, the simplest solution for repair would be to completely strip off the damaged sleeve; re-clean the pipe and re-apply a brand new sleeve.

     You can't go wrong doing that anytime, except, heat shrink sleeves are not designed to be easily removed from the pipe.  They are designed to stick to that pipe for the life of the line.  

     Because of that, I recommend instead that you trim off any damaged PE that you can safely trim off.  Then you fill the 'void' left in that coating with a Perp Filler material (a butyl mastic filler called S-1137 that is 2" wide, 10 feet long and a few mils thick - much like a putty; the mastic can be shaped and pressed into the void bringing a contiguous surface to the remaining portion of the damaged sleeve.

    

     From there, a new sleeve (preferably wider than the first) can be installed, adding a second layer to the good coating and completely encapsulating and isolating the originally damaged area.  Problem solved.

MODERATE DAMAGE

     I would consider "moderate damage" to cover anything from an area less than 3" x 3" and anything greater than a pinhole sized area of damage.  In that case, you would use the S1137 Perp Filler (just like we did for significant damage) and we would rebuild that damaged area.  We would then use a PERP (stands for Poly-Ethylene Repair Patch).  PERP is sold in rolls and "patches" are cut from that roll.  PERP doesn't shrink like other sleeves do, so you cut a patch that is at least 3 inches larger in every direction than the damaged area.  That patch is heated, patted down and rolled.  Once it cools it will be very well bonded to the underlying sleeve -- and your damaged area has been rebuilt, encapsulated and repaired. 

MINOR DAMAGE    

     Minor damage is what I would consider a pinhole.  Maybe someone poked the sleeve with a nail or welding rod while the sleeve was very hot and molten.  In that case, you would use a product called a Perp Melt Stick.  Perp Melt Sticks are cylinders of pure adhesive (think of it as being a bit similar to a candle).  With a torch, the Perp Melt Stick is heated -- and as that adhesive flows, you direct it into filling and sealing the pinhole.  

     So there you have it -- an incredibly overly simplified explanation of your heat shrink sleeve repairing options.  I can't stress enough:  if you have a problem:  CALL ME!  

PERP - MELTSTICK

Perp-Meltstick Coating Repair Stick

Repair System for Damaged Mill-applied PE coating.

  

Product Description: PERP MELTSTICK coating repair.

PERP MELTSTICK is a heat-sensitive, PE copolymer-based stick used for small super-ficial,
damage (scratches) to PE-coatings where the damage does not extend to the bare metal.

Installation is done with a standard gas torch. After eliminating all sharp edges, cleaning and preheating, PERP-MELT-STICK is heated above the damaged area until becoming glossy. No filler is required. The molten adhesive is spread onto the scratches, forming a tight bond with the substrate. After cool down, the hardening adhesive is smoothed flush with the PE line coating using a paint scraper.

Product Features/Benefits:

• Versatile and adaptable repair system that is highly economical.
• Resistant to high shear forces with durable reconstruction of the damaged coating.
• Excellent adhesion to commercial PE mill-applied coatings. Guarantees a virtually monolithic coating repair of high quality.
• Simple stick form makes installation faster and more convenient - saves time.
• No special equipment required makes installation fast and easy while keeping installation costs low.

Product Properties Guide

Max operating temperature: 80°C (176°F)
Compatible line coatings: PE
Min preheat temperature: 60-70°C (140-158°F)
Recommended pipe preparation: Brush
Soil stress restrictions: None

Length: 12.0 inches

Diameter: 1.0 inch

Softening point: 120°C (248°F)

Shear strength:  750 psi @ 23°C (73°F); 65 psi @ 80°C (176°F)

How Much Coating Repair Material Will I Need?

     Question:  I have a PE coated pipeline.  I've been told to have repair material on site.  How much polyethylene repair material will I need?

     Answer:  Unfortunately, it is almost impossible for me to know!  There are so many different ways that a pipeline can be damaged and so many varying degrees that I cannot ever predict how much you will have on your pipeline.  As a couple examples; here are some photos of damaged PE that I've seen:

Damage to the PE jacket outside of insulation caused by improper pipe storage

Damage to a PE outer jacket.  notice that the ROCS sleeve is untouched just a few inches away

Another area of PE damaged by a forklift

     In the real world, it is possible that PE coated pipe is loaded on a barge and every single joint of pipe is damaged to some degree.  It is also possible that a pipe is loaded without a single joint being damaged.  There is never any way for me (or the customer) to really know. 

     That is one reason that we keep so much PERP material in stock.  Very often, it isn't known how much damage a pipe has received during transit until the pipe is actually being strung up and welded.  In cases like that, it is very simple for us to throw a few rolls of PERP material - and the accompanying Perp Filler rolls onto a truck (or UPS) and have them at the job site in a day or two.

     You don't want to have to buy materials that you don't really need.  I don't want to sell you materials that you don't really need.  The fact that we keep this material in stock assures that we both get what we want. 

Pipeline Repair - Case Study

    

How many 'near miss' pipeline catastrophes occur each year?

     Last week, there was very nearly another major pipeline disaster in the southeastern United States.  Under ground, a high pressure, natural gas line has been in service for many years.  This pipeline is coated with coal tar (paper and all) and is doing exactly what it was designed to do.  If we're being honest, this line is doing more than it was ever asked to do; as the coatings applied 30+ years ago have prevented corrosion better and longer than the original engineers required them to! (Click HERE if you're interested in reading an article summarizing Coal Tar as a pipeline coating).

     In any case, this pipeline was quietly doing its job when WHAM.  A construction crew laying a new pipeline in the area accidentally gouged the side of the pipe; significantly damaging sections of the coal tar and (in a few cases) causing bare steel to be exposed.  My understanding is that there was no meaningful damage to the pipe wall itself.  Isn't that incredible all on its own?  A pipeline coating that was 1/4 of an inch thick (or there about) was completely scraped from the pipe in some cases; but the pipe itself was undamaged.  I've heard football described as "a game of inches" many times; but in this particular case 'Life' was a game of inches; as who could predict what might have happened if the back hoe had struck the pipe hard enough to cause a break in the steel; a spark; a disaster.  I imagine the crew was wide eyed when they realized what had almost just happened.

     All of this resulted in a fairly common phone call to us at Joint Specialists.  On the line was a man in the field; he had a representative from the gas company on the line as well.  The question was "I've got significant damage to an active natural gas line - what do I need to do to repair this coating?" 

     I walked them through the options (as discussed here) and we quickly came up with a custom solution and application procedure for getting the pipeline coating back intact as quickly, easily and reliably as possible.  Crisis averted.  Pipeline service not interrupted and hopefully the end user will get another 25 years out of that coal tar coated pipeline!

How Do I Repair A Damaged Shrink Sleeve or PE Line Coating?

Question:  How do I repair damage to a PE factory applied coating?

Answer:  We have several options; all are dependent upon the size and scope of the damage.  I will break it down as follows:

Pin Hole / Very Minor Damage

Perp Melt Stick in action, repairing minor damage

     For very minor damage, we offer what we call a Perp Melt Stick.  This is a stick of hot melt adhesive supplied in the form of a cylinder, 1" diameter by 12" long.  Using a propane torch, the melt stick is heated and the adhesive flows down to fill and cover the area of minor damage.  This is very similar to (but larger than) the commonly used FBE repair sticks that most people are familiar with.  This product is sold by the stick and is always in stock and ready to ship at Joint Specialists.

Minor to Moderate Damage

In the center of the pipe, we see the installed Perp patch.

     Perp, which stands for Poly Ethylene Repair Patch is a cross-linked, but not expanded product.  This means that it doesn't shrink.  Perp is sold as a roll of material and patches are cut in the field for specific sizes of damage.  As an example, if you have a 2" square damaged area; you would cut a piece of Perp at least 6" x 6" in order to have 2" of overlap on all sides for the proper seal to be made.

     In addition, Perp Filler is sold as a roll of mastic material and is used to rebuild the damaged area so that there is a flat surface to bond the Perp patch to.  This also helps avoid any entrapped air in the repair.

     For three layer repair requirements, a layer of S1301M epoxy primer can always be used as the initial coating (prior to applying Perp Filler and Perp Patch). 

Major Damage

      Lastly, for major damage, it is best to install a full encirclement shrink sleeve; chosen based upon the specific requirements of the pipeline (click HERE for more info).  In such a case, we are essentially treating the major damage as another field joint; coating, sealing and encapsulating the area with a shrink sleeve (after proper cleaning, etc of course).