Installation
How to install a wraparound heat shrink sleeve
Most sleeves that leak were fitted neatly. Neat and bonded are not the same thing.
Dig up a failed wraparound and it rarely looks like bad work. The wall is smooth. The seam is shut. The paint has turned. Water is inside anyway.
What failed was the bond, and the bond was decided in the first ten minutes, before any flame came out of the bag. Peel strength on these products is quoted against a prepared surface. The three-layer pipeline sleeve is rated at 100 N/cm to steel while cold. The method is ASTM D2671. That number describes blast-cleaned metal, not metal with mill scale on it.
So the running order is not a formality. Abrade, clean, warm, position, close, then heat outwards from the middle. The preparation steps are the ones a crew compresses when the trench is filling.
Two closure systems are covered here and they diverge at one step only. A cable wraparound carries its closure with it: the GWS Insulsleeve zips onto a stainless steel channel, the GMRS is held with heat-resistant tape. A pipeline sleeve is wrapped first, then held by a separate adhesive closure patch supplied against its code.
Not published for this product — the kit manual overrides this page
The manufacturer prints no installation sequence for the wraparound sleeve. Its datasheet carries selection charts and features, nothing procedural. What follows is The Overlap's reconstruction from three published Gala sources, all written for adjacent products: the flame instructions on the Polecap and Dock Pile Cap sheets, the four-step method on the InsulCap Live sheet, and the accessory list packed into the manufacturer's cable jointing kits. Gala puts an Installation Instruction Manual in its kits. Where that manual differs from anything below, follow the manual. On an energised feeder or a line under cathodic protection, that difference carries a safety cost.
The sequence
Nine steps. The first four take longer than the heating and matter more.
Fix the code, then read the overlap off it
Size against the outside diameter the sleeve must grip, never against the length of the tear. Then read the minimum lap for that code before the sleeve leaves its packet. A GMRS-30 wants 25 mm and a GMRS-250 wants 75 mm. It is the one dimension you cannot correct once the seam is shut. Rows on the size chart.
Abrade the whole bond area, not the wound
Gala packs aloxite emery tape into its jointing kits for exactly this. Abrade the full width the adhesive will touch, both sides of the damage, out to where the sleeve ends. On a coated pipeline that is bare steel across the cutback and polyethylene either side, because the hot-melt has to grip both in one wrap.
Mop and degrease, in that order
The same kits carry a mopping cloth and cleaning tissue alongside the emery. Abrading first and cleaning second lifts the dust you have created; reverse them and you polish grit into the bond line. Gala's InsulCap Live sheet opens its instructions with clean and degrease, before any flame is mentioned. Grease is invisible under a black sleeve.
Preheat cold or damp metal before the sleeve goes on
A pipe at ambient in a winter trench is a different job from the same pipe in a yard. Hot-melt must flow before it wets anything, and on the three-layer sleeve the softening point is 95 °C. The method is ASTM E28. Cold steel drains that heat as fast as the torch delivers it, so the outer wall recovers while the adhesive under it never softens. Warm the substrate, dry it, and keep it warm until the wrap is closed. No preheat temperature is published for these sleeves — ask for one in writing.
Position it, and choose where the seam sits
Centre the part so the damage sits mid-length with equal overhang each side. Then decide the clock position of the seam, which nothing in the literature decides for you. On buried pipe keep the closure patch off the six o'clock bedding face that backfill loads. In a duct keep the channel off the face the cable drags on.
Close the seam and measure the lap at both ends
Zip the stainless channel the whole length on a GWS, tape the seam on a GMRS, or lay the closure patch over the wrap on a pipeline sleeve. Then put a rule on the lap at each end, not in the middle, where it always looks generous. A substrate near the top of its band gives you the chart minimum and nothing spare.
Set the flame before you point it at anything
Gala prints its torch rule on the Polecap and Dock Pile Cap sheets. Propane is preferred to butane. The flame wanted is soft and blue with a yellow tip; a pencil-like one will scorch the wall. Keep it moving continuously. The InsulCap Live sheet gives the working part as the outer 3 to 4 inches of the flame, roughly 75 to 100 mm.
Heat outwards from the centre, in rings
Start at mid-length and work out to one end, then return to the middle and work out to the other. Keep every pass circumferential, so recovery closes as a ring and not a stripe. That drives trapped air and molten adhesive ahead of the shrink front and out at the ends. Begin at one end and you seal the air in.
Read the paint, read the bead, then leave it alone
Temperature-sensitive paint on the GWS sleeve changes colour when the shrink is complete, and that is the whole of what it certifies. It cannot see the adhesive, so a fully turned indicator sits happily over a dry bond. Recovery complete is not adhesion complete. Then let it cool: the Polecap sheet says to allow the part to cool before applying any mechanical strain, and that bond is worth 30 N/cm to steel while it is still at 50 °C.
Minimum overlap, by family and code
| Family | Codes | Substrate OD | Minimum overlap |
|---|---|---|---|
| Cable repair | GMRS-19 to GMRS-70 | 5 to 55 | 25 |
| Cable repair | GMRS-115 and GMRS-160 | 40 to 122 | 50 |
| Cable repair | GMRS-180 to GMRS-250 | 60 to 192 | 75 |
| Pole, wrap type | GPWS-502 | 70 to 122 | 50 |
| Pole, wrap type | GPWS-628 to GPWS-1335 | 70 to 360 | 75 |
| Pipeline | GTWS Ø159 to Ø1016 | 159 to 1016 | Not published |
Cable rows from the manufacturer's wrap-around sleeve datasheet, pole rows from the pole protection sleeve sheet for metal poles. All dimensions in millimetres. Published minimums on a fixed circumference, not targets.
The check before you backfill
Six things, in the order they become visible. Any one failing sends the sleeve back off.
- A bead of melted adhesive at both ends. Continuous means unbroken all the way round, not present at three o'clock and missing at nine.
- A bead along the closure too. The lap is the only interface that did not exist before the crew made it.
- A smooth wall, no wrinkles. The InsulCap Live sheet sets that as the finished condition. A wrinkle is trapped air with nowhere to go.
- No scorch, no charring. Overheated polyolefin cannot be rescued with more heat.
- Indicator paint fully turned, on codes that carry it, and only after the bead is confirmed.
- The part cool to the touch before the cable returns to its cleat, the U-bolt is re-torqued or the trench is filled.
Asked on site, usually too late
Can I use a hot air gun instead of a gas torch?
How much lap does a pipeline sleeve need, if none is printed?
The paint has turned but I cannot see any adhesive. Is it sealed?
Does overheating matter if the finished sleeve looks smooth?
Is the sequence the same on a standing pole?
Next
- Why wraparound sleeve repairs fail in the groundEach of these steps seen from an excavation, after it was skipped
- Heat shrink sleeve size chartGWS and GMRS rows, recovered walls and the full overlap column
- Reading a heat shrink datasheet without taking it on trustWhat a peel figure assumes about the surface it was measured on
- Wrap-around sleeve datasheetThe manufacturer's sheet: GWS and GMRS selection charts, with the overlap column
- Pole protection sleeve for metal poles, datasheetGPWS overlap rows and the epoxy paint pairing at the ground line
- Send a size, a substrate and a temperatureAmbient at installation changes the answer, so include it