Heat Shrink Coupler for Post-Tensioning Duct Joints (GMW)

About Heat Shrink Coupler for Post-Tensioning Duct Joints (GMW)

In post-tensioned concrete, each joint between lengths of tendon duct must be sealed so that concrete slurry does not leak in during casting and moisture cannot reach the tendons afterwards. Gala's Heat Shrink Coupler does that job. It is a tube of cross-linked polyolefin lined with hot-melt adhesive, supplied expanded in 300 mm pieces. Shrunk over the butt joint between two duct sections, it grips both ends while the adhesive melts and bonds to the duct, giving a tight, in-line connection.

It suits corrugated HDPE ducts and corrugated metal ducts, and works in wet or dry conditions. The shrunk coupler resists impact and abrasion on site, and its elastic recovery lets it conform to the corrugation profile.

Fitting needs no special skill. Cut the duct ends square, clean and degrease them, slide the coupler over the joint, then shrink it with a propane torch (butane also works) on a soft blue flame with a yellow tip, working from the centre towards both edges until adhesive appears at the ends. Let it cool before disturbing the joint. Two people are recommended for the larger sizes.

Seventeen sizes run from GMW 70/22 to GMW 863/250. Choose the size whose first figure (minimum inside diameter as supplied) passes over the duct's outside diameter and whose second figure (maximum inside diameter after recovery) is smaller than it. Custom dimensions, lengths and colours are available on request.

Manufactured by Gala in India. Datasheet and size selection on request.

Specifications

• Brand: Gala
• Product type: Heat shrink coupler (adhesive-lined sleeve) for post-tensioning duct joints
• Material: Cross-linked polyolefin with hot-melt adhesive lining
• Colour: Black
• Operating temperature: -40 deg C to +110 deg C continuous
• Shrink ratio: About 3.2:1 to 3.6:1 by size (supplied ID / recovered ID)
• Size range: 70 mm to 863 mm supplied ID; 22 mm to 250 mm recovered ID
• Wall type / thickness: 2.7 mm to 3.5 mm after recovery (+/-10%)
• Adhesive / sealant: Hot-melt adhesive lining
• Standards tested to: Test methods quoted on GSF's datasheet - ASTM D638, ASTM D2671, ASTM D2240, ASTM D570
• Application: Sealing joints between corrugated HDPE or metal post-tensioning ducts
• Installation: Propane torch, soft blue flame, centre outwards until adhesive shows at both ends
• Country of origin: India
• Shrink temperature: 125 deg C
• Length: 300 mm per piece
• Tensile strength: 12 MPa min (ASTM D638)
• Elongation at break: 350% min
• Hardness: 45 +/- 10 Shore D
• Water absorption: 0.5% max

Sizes

• GMW 70/22 | D 70 / d 22 | T 2.7
• GMW 90/28 | D 90 / d 28 | T 3.0
• GMW 105/30 | D 105 / d 30 | T 3.0
• GMW 115/34 | D 115 / d 34 | T 3.2
• GMW 130/36 | D 130 / d 36 | T 3.2
• GMW 140/42 | D 140 / d 42 | T 3.2
• GMW 160/50 | D 160 / d 50 | T 3.3
• GMW 180/55 | D 180 / d 55 | T 3.3
• GMW 200/60 | D 200 / d 60 | T 3.5
• GMW 250/70 | D 250 / d 70 | T 3.5
• GMW 320/90 | D 320 / d 90 | T 3.5
• GMW 375/110 | D 375 / d 110 | T 3.5
• GMW 425/125 | D 425 / d 125 | T 3.5
• GMW 550/157 | D 550 / d 157 | T 3.5
• GMW 680/200 | D 680 / d 200 | T 3.5
• GMW 760/215 | D 760 / d 215 | T 3.5
• GMW 863/250 | D 863 / d 250 | T 3.5

Applications: Post-tensioning contractors, bridge and flyover construction, metro and rail viaducts, prestressed concrete buildings, nuclear and industrial structures, infrastructure EPC contractors