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Monday, February 16, 2015

WPC Shrink Sleeve Installation Procedure

Two Piece WPC Heat Shrink Sleeve Install

     WPC sleeves (available in numerous different variations: WPCT, WPC100M, WPC60, WPC80, WPC120, WPC65M - though this post focuses specifically on the mastic coated sleeves and WPCT in particular) are composed of irradiated, modified polyolefin backing which upon brief exposure to a temperature in excess of 125C, will shrink from its expanded diameter (as supplied) to a predetermined recovered diameter.  The WPC sleeves are precoated internally with a controlled thickness of a thermally activated, self priming, rubber modified thermoplastic adhesive that provides an excellent bond to the metal pipe and yard applied coatings.

     During installation the sleeve is wrapped loosely over the joint and closed with a heat activated 'closure' patch (WPCPIV).  The patch is manufactured so that with proper heating the fiber mesh built into the closure backing becomes visible, giving the appearance of an alligator skin texture to the closure strip.

     Internally, the patch is coated with a heat activated high shear adhesive which assures a reliable closure.
Here you see the shrink sleeve and the closure strip as separate parts.
Now on to the install:

Step 1:  Joint Preparation.
  • Remove all weld spatter by grinding, filing or chipping
  • The exposed steel should be power brushed to a near white metal (as with all coatings, the cleaner the surface, the better the bond)
  • The steel and yard coated areas should be wiped clean of foreign materials such as dirt, rust, oil, grease and moisture just prior to installation.
  • The sleeves shall not be applied during rains or sandstorms unless portable welding tents or equivalent are used.  
  • Please note: WPCT (just like WPC65M and WPC100M) requires no primer or epoxy bonding agent.

power wire brush pipeline
Field joint being cleaned with a power wire brush

Step 2:  Preheating of the Joint Area

  •  Preheat the joint area and the adjacent yard coating using a propane torch, induction heater or ring burner.
  • WPCT to be preheated to a minimum temperature of 140F
  • WPC65M to be preheated to a minimum temperature of 165F
  • WPC100M to be preheated to a minimum temperature of 212F
  • It is always necessary to verify the temperature with tempil sticks, contact pyrometer or equivalent. 

FH2601 Torch Kit
Field joint preheating with a JS-2601 Torch Kit

pipeline preheat temperature
Verifying that proper preheat temperature has been reached
Step 3:
  • After preheating (and verifying preheat temp) remove the protective release paper and wrap the shrink sleeve centrally around the weld joint.  
  • The sleeve will overlap itself by at least 50mm

Wrap the sleeve around the pipe

Sleeve will overlap onto itself. 
Closure Patch
Closure secured at sleeve overlap.
heat shrink patch
Closure is secured using torch to activate the high shear adhesive.

shrink sleevepipe coating
Start shrinking on one end of sleeve and work toward other always shrinking circumferentially.

Continue shrinking sleeve until it fully conforms to pipe surface.

The finished WPCT sleeve will be fully conformed with weld bead visible.

Mastic flow will be evident at sleeve edges (this is where the seal is).

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