Commonly used pipes in water supply system are given below.
- Cast Iron (CI) Pipes
- steel pipes
- Galvanized Iron (GI) Pipes
- copper pipes
- plastic or polythene or pvc pipe
- Asbestos Cement (AC) Pipes
- concrete pipe
1. Cast Iron Pipes
These pipes are mainly used in the water distribution system for the following reasons.
- they are cheap in cost
- It has high resistance to corrosion
- it is extremely durable
CI pipes are manufactured by the following 4 methods.
- Horizontally Cast (MC Ware Pipe)
- vertical cast (cast pit in sand molds)
- Centrifugal cast into sand lines, spun type:
- Centrifugally poured into water cooled metal molds
Nowadays horizontally cast CI pipes are not used.
Centrifugally cast pipes have a fine grained dense structure and uniform thickness and are therefore widely used.
During transportation and making connections to these pipes, special care must be taken to prevent damage.
2. steel pipes
The use of steel pipes in a water supply system is suggested when,
- There is a lot of pressure on the pipes (ie above 7 kg/cm2)
- Large diameter pipe required
Steel pipes are used because they are stronger and lighter in weight than CI pipes.
However, these pipes require adequate preventive measures to maintain the adverse atmospheric conditions.
When steel pipes are wrapped in cement mortar or cement concrete, they are called Hume Steel Pipe,
3. Galvanized Iron (GI) Pipes
This type of pipe is used for water supply work inside the building. These pipes are wrought steel pipes which are provided with zinc coating.
They are available in light, medium and heavy grades depending on the thickness of the metal. For 15 mm GI pipe, the thickness is 2.0, 2.65 and 3.25 for light, medium and heavy grades respectively. Generally medium range pipe is used for internal plumbing in the building.
Mostly screw and socket joints are used for GI pipe.
4. copper pipes
These pipes are used in the installation of hot water. They have high tensile strength and therefore can have thin walls and can be bent easily.
Copper pipe is sometimes coated with chromium to enhance its appearance.
5. Plastic or Polythene or PVC Pipes
These pipes are being used these days for cold water supply in external and internal plumbing works.
They are light in weight, non-corrosive, low in cost and require no threading for connection.
There are 3 common types of plastic pipes available in the market, as given below.
- Unplasticized PVC (UPVC) or rigid pipe for use with cold water
- Plasticized PVC pipes that are plasticized with the addition of rubber. It has lower strength and lower working temperature than UPVC pipe.
- Chlorinated PVC (CPVC) pipe that is 120 . can withstand high temperatures of up to0 (used to carry hot water)
For pipes used in soil and wastewater discharge systems, the wall thickness shall be greater than the thickness used for roof drainage.
45. Rigid PVC pipe is used for the distribution of water at temperatures below0C.
At higher temperatures, the strength of the pipe decreases. Similarly, ultraviolet radiation from sunlight and frequent changes in temperature shortens the life of PVC pipe.
These pipes are costlier than AC pipes but cheaper than GI pipes.
6. Asbestos Cement (AC) Pipes
These pipes are also used for drainage and ventilation of rainwater from roofs, soil and waste. They come in two profiles – one with beading around the socket (WB) and the other without beading around the socket (WOB). The latter type is more common than the former.
Pipes come in lengths of 3 metres.
The main drawback of these pipes is that they are heavy and break easily.
These pipes are cheaper than PVC pipes.
7. concrete pipe
Unreinforced pipes of smaller diameter as well as reinforced and prestressed concrete pipes of larger diameter are available for water supply and other uses.
Small non-reinforced concrete pipes are heavily used to drain rainwater.
Large diameter pipes are generally used for major water supply works.