Science Fair Project Encyclopedia
Types of Pipe
Types of pipes for different plumbing usage may vary, even inside a country, by local building codes and customary usage.
Most modern domestic water piping is now in copper (although plastic has become the material of choice in recent applications). Copper is a good material because it is durable, light and easy to work with. Copper pipes are usually joined with the use of compression fittings or soldered (either by hand or using Yorkshire Fittings).
The use of lead in solders has been subject to the same criticisms as lead pipes, so lead-free solders are now in use. Green residues in bathroom fixtures are indicative of acidic corrosion in copper pipes.
Copper pipes usually mate with plastic pipes (e.g. the feed into a power shower ) with push fit fittings.
Flexible copper tubing is gaining popularity for new or retrofit gas systems because of speed of installation. The joints must be either brazed or flared, and the tubing painted yellow and labelled.
High strength plastic piping is sometimes used for both mains water and gas feeds, its main strengths being its resistance to the corrosive effects of being underground and its light weight.
In domestic plumbing, several types of plastic are used. These include rigid polyvinyl chloride (PVC) for cold water and waste systems, flexible high density polyethylene (HDPE) for cold water, flexible polybutylene (PB) for hot and cold water. Some flexible pipes are braided with stainless steel wire. Domestic plastic pipes with hot water feeds of the CPVC type use a special solvent.
Domestic plastic pipes are generally glued, called solvent welding; however, threaded, push-fit or speed-fit fixings are sometimes used. Compression fittings are common when the plastic must connect with metallic pipes or fixtures.
Usually used to provide drainage to low-lying fields or lawns, it is sometimes used in the portion of the waste systems outside the building. Often called field or drain tile.
Commonly used in older houses and for gas lines. Threaded steel pipes are heavy and prone to rusting and leaking, especially in hot water lines, but continue as the material of choice for domestic small diameter gas lines. However copper pipes are now widely used (in the UK at least) for internal domestic gas. Steel is still widely used for compressed air.
Cast iron pipes are used to provide drainage in homes and businesses. Sometimes it is required by building codes. The advantages are that it provides better protection against noise and heat expansion than plastic pipings, and offers a very long lifespan. Cast iron can be reclaimed from a demolished building and recycled. The drawbacks of cast iron are that it is expensive and very heavy.
Epoxy Pipe Lining
A more recent technology in the plumbing field is epoxy pipe lining. Used mainly to line existing copper piping systems down to half an inch in diameter. The epoxy lining is used to rehabilitate the interior of the pipe. In coating the inside of the pipe, the epoxy resin prevents any future contact between the copper and water thus stopping any further corrosion.
Epoxy is an excellent material because it does not interact with water. Unlike metals which do interact with water, causing the metal to eventually corrode.
Typically the pipes are sand blasted from the inside to profile the interior surface of the pipes, cleaning and roughing up the surface. Then a mixture of epoxy resins is shot into the existing plumbing system with high air pressure, coating the inside of the pipe with a thin layer of epoxy.
- Plumbing drainage venting
- Domestic water system
- Plumbing fixture
- Building construction
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