Radiation crosslinked heat shrink bend joint

Radiation crosslinked heat shrink bend joint

Bend joint is designed for changing the direction of the preinsulated pipeline to any angle between 0°-90°. It is meant for jacket pipes of diameter 90 mm to 160 mm.


Bend joint is designed for changing the direction of the preinsulated pipeline to any angle between 0°-90°. It is meant for jacket pipes of diameter 90 mm to 160 mm. The change of pipeline’s direction is necessary during the construction of the pipeline network due to some specific land shape or some obstacles. In this situation the preinsulated bends are installed with the use of two standard joints. Such solution influences much on the cost of the investment.
The alternative solution is a flexible bend joint which allows for re-directing of the pipeline to any angle.
The main advantage of the bend joint is lowering the cost of installation by reducing the quantity of straight joints and steel bends in favour of flexible joint.
The bend joint is produced from radiation crosslinked polyethylene which results in shape memory and high shrink strength. These features guarantee performing the reliable and tight bend joint. The warmed up accordion-folded part may be bended to maximum 90°.

Before sliding the heat shrink bend, the spacer should be put on the welded steel bend. Then one should warm up the accordion-folded part of the heat shrink bend joint and slide it onto the steel bend. Next steps are similar to installation of standard joints and reduction joints. After shrinking of the joint’s ends and foaming the joint, one should fuse in the welding plugs. The plugs are welded into non-crosslinked area which results in the fusion of the plug’s and the joint’s materials. This kind of welding is prone to any moisture leaks and guarantees tightness and long life of the joint.


  • has a ground load test certificate (so-called sand box) for 100 cycles in accordance with PN-EN 489: 2009,
  • the knee joint is made of high density black polyethylene, radiation cross-linked,
  • high mechanical strength of cross-linked material ensures resistance to tearing and abrasion,
  • the use of appropriate sealing in the sleeve protects the joint area in difficult conditions,
  • the small number of elements forming the muff reduces the assembly time to minimum, and thus increases the assembly efficiency of the muffs and reduces the cost of the joint, the muffs are resistant to corrosive chemical agents and UV radiation.

Selection of radiation crosslinked knee heat shrinkable joints with PUR foam for pre-insulated heating networks.

Type of bend joint Joint dimesions [mm]
Inside diameter
Total length
Length of straight
Diameter of
foaming part
Gauge of foaming
Approx. length of
MK90MW 110 840 220 20 535 400
MK110MW 135 895 220 20 590 455
MK125MW 151 925 220 20 610 485
MK140MW 166 930 220 20 610 490
MK160MW 187 930 220 20 610 490
MK200MW 225 1055 220 20 775 615
MK225-250MW 275 1190 220 20 890 790

As standard, the bend joints are produced with butyl rubber (MK..MW).
On special request the bend joints are available in other sealing variants.

Content of the joint set

  • Heat shrink joint radiation crosslinked with factory made holes
  • 2 venting plugs
  • 2 welding plugs
  • 2 cleaning tissues
  • Mounting instruction

Extra accessories for bend joints

In order to install the heat shrink bend joint properly one should use steel bend of matched dimensions and radius. The steel bends are supplied for request.
Each steel bend by RADPOL is supplied with a ring spacer. Non-standard steel bends are supplied for requests.

Steel bend dimensions

Type steel bend Type of bend joint
Inner diameter
DN [mm]
DZ [mm]
Wall thickness
Bend radius
20 26,9 2,3 125 MK90MW
25 33,7 2,6 125 MK90MW
32 42,4 2,6 150 MK110MW
40 48,3 2,6 150 MK110MW
50 60,3 2,9 170 MK140MW
65 76,1 2,9 180 MK160MW
80 88,9 3,2 200 MK200MW
100 114,3 3,6 240 MK200MW
125 139,7 3,6 310 MK225-250MW
150 168,3 4,0 310 MK225-250MW