Hynds Hylock Joint Restraint System

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The Hylock Joint Restraint System for concrete pipes has been developed by Hynds to mitigate excessive joint flexure and extension as a result of significant movement in a seismic event or through differential bedding movement.
The Hylock Joint Restraint System is covered by New Zealand Patent 615291


  • Strong, resilient, flexible, versatile
  • Provides a continuous connection of a series of concrete pipes
  • Chain link effect allows controlled movement at the joints
  • Will break at pre-determined range of loads in the event of excess joint movement
  • Easy to determine the load capacity of the restraint joint
  • Incorporates rubber seismic shock absorber mushrooms around the joint that help protect the surrounding concrete at the joints
  • Modified collar to provide 20 mm nominal joint gap which allows for greater movement at the joint
  • Suitable for spigot and socket RJ pipes DN900–1800 mm and DN1950–2100 mm in-wall jointed pipes
  • Suitable for butt jointed jacking pipes
  • Can be used to connect to end structures such as manholes and pump stations
  • Restraint assembly easy to connect after pipe is laid
  • Restraint assembly may be replaced after failure
  • Visual inspection possible after a seismic event

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