Three Layer Field Joint Coating

 3 Layer Field Joint Coating

   

     In many parts of the world, three layer factory applied pipe coatings are the dominant selection.  In those cases, those three layers are typically:  Epoxy, Adhesive and Backing.  These coatings have been proven in countless situations.  Polyethylene offers excellent abrasion resistance, electrical resistivity and cathodic disbondment values.  All critically important technical properties for a pipeline coating to have.

     In order to re-create that factory applied coating system on a field joint, Raychem (a number of years ago) created the HTLP sleeve system.  HTLP mimics that factory applied coating and offers a contiguous coating type for the length of your pipeline.  

    With HTLP80 you get the following layers:

• primary corrosion coating:  S1301M Epoxy Primer
• second layer:  a high shear hot melt adhesive that chemically and physically bonds to the S1301M.
• outermost layer:  radiation crosslinked heat shrinkable polyolefin

     If you have questions, shoot me an email!  Steve@jsicoatings.com

HTLP80: An Excellent Three-Layer Polyethylene Pipe Coating

 HTLP80: An Excellent Three-Layer Polyethylene Pipe Coating

When it comes to girth weld protection systems for three-layer coated pipes, HTLP80 stands out as the most widely used solution. HTLP80 is a highly effective three-layer polyethylene pipe coating that provides exceptional protection for pipeline girth welds. This product has gained widespread recognition and is trusted by industry professionals around the world. Let's delve into the features, benefits, and specifications that make HTLP80 an excellent choice for pipeline coating.

Product Description: HTLP80 is part of the HTLP series, which includes HTLP60 and HTLP80 field-joint coatings. The construction of HTLP80 comprises a three-layer system:

1. First Layer: Liquid Epoxy - This solvent-free, two-component epoxy acts as the initial layer, applied directly to the prepared pipe surface.

2. Second Layer: High Shear Strength Copolymer Adhesive - The copolymer adhesive provides excellent bonding properties and enhances the overall strength of the coating.

3. Third Layer: Radiation Cross-Linked, High-Density Polyethylene (PE) with PCI - The outer layer consists of radiation cross-linked, high-density polyethylene, which offers a tough barrier against mechanical damage and moisture transmission. It includes a Permanent Change Indicator (PCI) for easy post-heat inspection.

HTLP80 is designed as a wrap-around heat-shrinkable sleeve, emulating the structure and performance of mill-applied three-layer PE coatings. It also exhibits remarkable compatibility and can be used with various other mill-applied coatings.

Product Features and Benefits:

1. Superior Resistance: HTLP80 is fully resistant to shear forces induced by soil and thermal movements. It withstands external stressors, ensuring long-term durability and reliability.

2. Strong Mechanical and Chemical Bonds: During installation, the epoxy layer creates strong mechanical and chemical bonds to the pipe surface and copolymer adhesive. This combination enhances the overall strength and performance of the coating.

3. Optimum Corrosion Protection: HTLP80 offers superior cathodic disbondment resistance and excels in hot water immersion tests. It provides an effective barrier against corrosion, ensuring the longevity of the pipeline.

4. Monolithic Coating System: By reconstructing the coating of three-layer coated pipes, HTLP80 enables the pipeline to have a virtually monolithic coating system. This seamless protection further enhances the integrity of the pipeline.

5. Easy Inspection and Application: The dimpled backing of HTLP80 serves as a "permanent change" indicator for the application of heat. It ensures correct heat application and allows for easy post-heat inspection, providing reliable inspectability at any time.

Product Selection Guide: HTLP80 is specifically designed for higher operating temperatures compared to its counterpart, HTLP60. Here is a summary of the selection guide for HTLP80:

• Max Operating Temperature: 80°C (176°F)
• Compatible Line Coatings: PE, PP, FBE, Coal Tar
• Min Preheat Temperature: 70°C (158°F)
• Recommended Pipe Preparation: SA 2½
• Soil Stress Restrictions: None
• Performance: EN 12068 Class C60 UV, Class C80 UV

Product Properties: HTLP80 exhibits excellent physical properties, as outlined below:

• Backing:

  • Tensile Strength: 3000 psi (20 MPa)
  • Elongation: 580%
  • Hardness (Shore D): 55
  • Shrink Force: 40 psi
  • Dielectric Strength: 500 volts/mil (20 kV/mm)
  • Moisture Absorption: 0.05%

• Adhesive:

  • Softening Point: 120°C (248°F)

WPC100M Shrink Sleeves With S1301M Epoxy

WPC100M used with Epoxy?

      I had the question today:  do we have to use S1301M epoxy with the Covalence WPC100M shrink sleeves?  The answer is a simple one: absolutely not. 

     WPC100M is designed to be installed as a stand alone pipeline coating, requiring no primers or epoxies.  I would say that in 99.9% of the jobs that I've been a part of that have installed WPC100M shrink sleeves as their field joint coatings there was no epoxy used.  The WPC100M system just wasn't created to require an epoxy primer.

     Having said that; the sleeve system will still work if you use the epoxy.  The sleeve system will still perform well (perhaps even better in some areas like cathodic disbondment) if installed over epoxy.  It just isn't necessary.

     At the same time, though - it is possible that the specifics of this job could preclude using the S1301M epoxy.  If you're working on an offshore lay barge; it is unlikely that anyone is going to want to waste the time waiting for an epoxy to cure (even though it cures very quickly).  In addition, sometimes an epoxy acting as a primary corrosion coating requires a greater level of steel cleanliness prior to install.  In many cases, a wire brushed pipe surface just isn't going to be sufficient to get the type of bond you're looking for.

     So, NO- I believe the WPC100M shrink sleeve is an excellent pipe coating all on its own; without introducing a two part epoxy into the picture.  But it is your money - and if you're prefer to spend a little bit extra in order to improve the performance of the well proven shrink sleeve a little bit - then who am I to stop you? 

Three Layer Heat Shrink Sleeve System

Question:  Which Covalence heat shrink sleeve system is specifically designed to be used with three layer polyethylene (TLPE) factory applied coatings?

Answer:  HTLP60 and HTLP80 are specifically designed to recreate the factory applied TLPE coating at the field joint.  Rated to 60C or 80C (respectively) HTLP products do exactly that.  Utilizing Covalence S1301M liquid epoxy and an HTLP60 heat shrink sleeve, the HTLP heat shrink sleeve system takes the best that liquid epoxy offers; the best that high shear adhesives offer and the best that a heat shrink sleeve backing offers and bundles it all up into one cohesive; fantastic pipeline coating.

HTLP is also compatible with FBE, CTE and other commonly used pipeline coatings (though not typically PP).