Encasement of pipes


Pipe Classifications and Pressure Ratings

For structural purposes pipes shall be classified into two groups:

Group A: Rigid pipes which do not depend on lateral support from the bedding and trench sides for structural strength.

Pipe materials include:

  • Concrete
  • Clayware
  • Asbestos Cement
  • Pitch Fibre
  • Grey Iron

Group B: Flexible pipes which depend on lateral support from the bedding and trench sides for structural strength and to prevent distortion.

  • Pipe materials include:
  • GRP (Glass Reinforced Plastic)
  • uPVC (unplasticised Polyvinyl Chloride)
  • HDPE (High Density Polyethylene)
  • PP (Polypropylene)

Pressure pipes shall be supplied to the following rated pressure classifications:

  • Asbestos Cement 18 bar
  • GRP 12 bar
  • uPVC 12 bar (12 bar rated uPVC pipes
  • used to allow for
  • Temperature derating).

Joint Requirements and Limitations

Unless pipes are detailed with rigid joints or are specified differently all pipelines shall be jointed with approved mechanical, flexible joints with elastomeric joint rings. The whole joint assembly shall be compatible with the pipe construction and with the specified performance of the completed pipeline.

Flexible Joints

Flexible joints shall be as a separate sleeve coupling and double spigot assembly with two sealing rings.

Elastomeric joint sealing rings shall be manufactured to EN-681-1 from ethylene propylene rubber (EPDM) and shall have a hardness measured in International Rubber Hardness Degrees (IRHD) compatible with the pipe material.

Deflection: The completed joint shall be capable of accepting the following ranges of deformation when subjected to internal pressure without losing its seal at the specified test pressure, without direct contact between spigot and socket/coupling and without inducing stresses or strains in the pipe material beyond the safe working limits.



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