SEQ Water Supply Code - Part 1 (Planning and Design), Clause 7.9
Generally, a fully restrained PE pipe system does not require the use of anchorage. The restrained system may be provided through welded joints, restrained couplings or flanges. Designers shall assess the needs for anchorage i.e. ends of mains or transition between different pipe materials. The transition areas shall be restrained with concrete thrust restraints.
Pipework that is subject to thrust forces must have appropriate thrust restraints (e.g. thrust blocks). For example, PE pipework must have a ductile iron thrust connector with in-line thrust restraint where it transitions to non-PE pipe material.
The purpose is to restrain unbalanced forces and prevent joint separation caused by internal pressure and shortening/lengthening due to temperature changes and Poissons effect.
Refer to the Code
Thrust block design
Thrust blocks must be designed for a minimum test pressure of 1200kPa. Refer to standard drawings SEQ-WAT-1104-1 (Detail A: In-line connection), 1205-1, 1206-1, 1207-1, 1208-1.
Note: The standard drawings do not apply in soils with less than 50kPa bearing capacity. A geotechnical assessment and individual design is required for these soils.
Design drawings must show the thrust force and direction (refer SEQ-WAT-1101-2).
Important consideration: Where excavation is proposed in the vicinity of existing live pipelines, the effect of removing soil behind unrestrained fittings/thrust blocks must be considered. Alternative thrust restraint must be implemented (or the live pipelines temporarily shut-down) to ensure work health and safety risks are addressed.