WWD P Trap Landing

Terminal Manhole Connection / P-Trap

Typically referred to as a P-trap, this is a fabricated polyethylene equivalent to a traditional cast iron P-trap. It shares similar dimensions as traditional Cast Iron P-Traps and meets the DSD requirements.

P-traps are installed at the base of terminal manholes to prevent sewer gas (H2SO4) and odours escaping from the manhole within confined areas such as inside the basements in buildings. The expected service life of a PE100 P-Trap is 100 years. Cast Iron P-Traps need to be replaced after 15-20 years of service due to internal corrosion. Polyethylene P-Traps have a 100 year maintenance free life.

When PE is cast into concrete there is no adhesion between PE and cement. Due to thermal expansion during curing there is a small gap between the PE and the cured concrete after cooling, this gap allows wastewater to leak past the PE fitting. Hydrophilic seals are fitted where the PE meets and exist the concrete, these expand up to 600% when wet and seal around the PE and the concrete chamber walls.

If you are connecting PE pipes to an existing Cast Iron P-Trap click here

Polyethylene P-trap installation

With a PE P-Trap, no anchoring is required, the M90SE PE pipe is electro fused directly to the spigot of the Polyethylene P-Trap, which is cast into the manhole chamber. This is the lowest cost option and provides a 100 year maintenance free drainage system.  

PE P Trap Connection

Polyethylene P-Trap Manufacturing

All Mill-Pro P-Traps are manufactured using only Butt Welding techniques in accordance with BS ISO 21307, including on the rodding connection. No extrusion welding is used in any Mill-Pro drainage fitting manufacture. Extrusion welding is structural weak and is banned under DSD Appendix 5A, Clause 5.4.