Pipe Classifications and Pressure RatingsFor 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:
- 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
- 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 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.