Galv Mall M&F Union-257G 3/4

Commercial plumbing covers pipe systems, fittings and valves for larger buildings, plant rooms and industrial services. The range includes stainless steel press and weld fittings, PVC-U, ABS and PP-R plastic systems, polyethylene for buried supplies, flanges, unions, pressure reducing valves and drain taps.

Systems and how they join

• Stainless steel press: fittings crimped onto the pipe with a pressing tool. Gas fittings are a separate range from water fittings, so use the version made for the service.
• PVC-U and ABS: solvent welded. Each plastic needs its own cement, as the cements are not interchangeable.
• PP-R: polypropylene pipe for hot and cold water, covered by BS EN ISO 15874. It is joined by heat fusion: socket fusion on a heated welding tool, electrofusion fittings, or butt welding on larger sizes.
• Polyethylene: PE pipe for water supply to BS EN 12201, joined with electrofusion couplers and tapping saddles after the pipe surface has been scraped clean.

Sizes, ratings and flanges

Plastic systems are sized by the pipe's outside diameter in millimetres, while many metal fittings and valves use inch thread sizes or DN nominal sizes, so check how each part is sized before mixing systems. A PN figure is the nominal pressure in bar at 20°C, and the safe working pressure falls as temperature rises. Steel flanges are made to BS EN 1092-1, with dimensions set by both the DN size and the PN rating, so match both when joining a flanged valve to pipework.

Regulations

Pipes and fittings on drinking water must be suitable under the Water Supply (Water Fittings) Regulations 1999. Work on gas pipework must only be carried out by a Gas Safe registered engineer.

For standard domestic sizes, see pipe systems and fittings or browse valves.