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    Pipes used in plumbing


    Depending on the age of the property the plumbing systems will have metal or plastic pipes, although it is not uncommon to find both. In the past all hot water pipes were metal but plastic pipes are now widely used.


    Metal pipes

    Copper pipes are the most popular type as they resist corrosion and are relatively soft, making them easy to work with. However, brass and stainless steel pipes are sometimes used for aesthetic reasons. Metal pipes are joined with soldered capillary joints, compression joints or with push-fit joints.

    Copper pipe

    The most common type of metal pipe in domestic properties is half-hard copper pipe. It can be used for both supplying hot and cold water and to connect the heating system. Copper pipes are available with 15mm (3/8in) and 22mm (3/4in) diameters and sold in 2m and 3m (6ft and 9ft) lengths.


    Chrome-plated copper pipe

    The most common type of metal pipe in domestic properties is half-hard copper pipe. It can be used for both supplying hot and cold water and to connect the heating system. Copper pipes are available with 15mm (3/8in) and 22mm (3/4in) diameters and sold in 2m and 3m (6ft and 9ft) lengths.


    Micro-bore copper pipe

    This small tubing is used in micro-bore heating systems and can be bent by hand. Micro-bore piping is sold in 10m and 25m (30ft and 75ft) lengths and comes in a range of diameters, the most common being 8mm and 10mm.


    Plastic supply pipes

    Originally used just for drainage, plastic pipes can now carry the water supply and connect the heating system. Plastic piping is easier to work with as it does not require soldering and has the added advantage of not being prone to a build up of scale in hard water areas.

    The main disadvantage of plastic piping is that as it is less rigid than copper, long pipe runs will require more support. There may also be a limit to the level of heat it can withstand, so the pipe's specification should always be checked. Also, plastic pipes should not come into close proximity with the boiler. The 300mm (3ft 1in) of piping running from the boiler should always be copper. Remember that plastic pipes should never be used for gas or oil supplies.


    CPVC (chlorinated polyvinyl chloride) pipe

    This rigid plastic pipe can be used for both hot and cold water pipes and for waste systems. However, some local authorities restrict its usage as a supply pipe, so it is important to check before installing.


    PB (polybutylene) pipe

    Also known as Hep2O pipe, this is an extremely flexible pipe used for domestic hot and cold water supplies. This type of pipe is joined using Hep2O push-fit joints or with compression joints (ensure the compression joints have a metal support sleeve). PB pipe is sold in either straight lengths or coils.


    PEX (cross-linked polyethylene) pipe

    Another alternative for carrying hot and cold water indoors is PEX pipe. Once again it is flexible and can be joined with speedfit joints or with compression joints (ensure the compression joint has a metal pipe insert). Today PEX pipe is often used for underfloor heating systems.

    Plastic waste and drainage pipes

    Drainage pipes are larger than the pipes used for carrying hot and cold water throughout the property. Drainage pipes take wastewater from the property to the main drainage system and are usually 32mm (1 ¼ in) or 40mm (1 ¾ in) or 50mm (2in) in diameter.

    Pipes with a 40mm (1 ¾ in) or 50mm (2in) diameter are used for the waste pipes of sinks, baths and shower trays. Washbasins are fitted with a waste pipe with a 32mm (1 ¼ in) diameter. An even smaller pipe with a diameter of 22mm (3/4 in) is recommended for the overflow pipe from cisterns. Pipes for soil stacks are larger with a diameter of 110mm (4 ¼ in).


    ABS (acrylonitrile butadiene styrene) pipe

    One of the first types of rigid plastic pipe used for drainage and soil stacks.

    PVC (polyvinyl chloride) pipe

    Used more widely today than ABS pipe, PVC pipe does the same job.

    Polypropylene pipe

    A more flexible version of ABS and PVC, polypropylene pipe is also used in waste systems. It can only be joined using push-fit or ring-seal joints - it cannot be solvent welded.

    UPVC (unplasticised polyvinyl chloride) pipe

    Brown UPVC pipe with a 110mm (4in) diameter is generally used for underground drainage, whereas grey pipe in the same material and of the same size is used for soil stacks.



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