They cannot withstand high pressure and are difficult to repair. But they are very heavy and difficult to handle and transport. The surface of these pipes is not affected with the time therefore, the carrying capacity does not reduce. These are not corroded by the water, therefore, have long life, above 75 years. In difficult areas pipes can be constructed at the site by using local materials. Larger diameter pipes are jointed together by means of collar joint with a rubber gasket or fibre filled lead gasket placed between the two ends of the pipes. Normally 1:2:2 concrete mix is used in the manufacture of concrete pipes. Sometimes mesh reinforcement is provided, but pipes with cylinder pipe reinforcement are more water tight and strong. The concrete is placed around the reinforcement by centrifugal process. pipe consists of a welded steel cylinder with high tension wire wound over it. Precast pipes are manufactured in factories and then transported to the site. (ii) Pipes having fabricated reinforcement and cast by centrifugal methods and curing in tanks. Steel pipes are not used in distribution system, owing to the difficulty in making connections. The life of these pipes is 25 to 50 years which is much short as compared with cast iron pipes. These pipes are much affected by corrosion and are costly to maintain. The disadvantage of these pipes is that they cannot withstand external loads, if partial vacuum is created by emptying a pipe rapidly, the pipe may be collapsed or distorted. They are also cheap, easy to construct and can be easily transported than cast iron pipes. Steel pipes are more strong have very light weight and can withstand high pressure than cast iron pipes. The construction of these pipes is similar to wrought iron pipes, it is occasionally used for main lines and at such places where pressures are high and pipe diameter is more. To increase the life of these pipes sometimes these are galvanized with zinc. Wrought iron pipes are joined together by couplings or screwed and socketed joints. These pipes should be used only inside the buildings, where they can be protected from corrosion. If compared with cast iron, these are more lighter, can be easily cut, threaded and worked give neat appearance if used in the interior work.īut it is more costly and less durable than cast iron pipes. Wrought iron pipes are manufactured by rolling the flat plates of the metal to the proper diameter and welding the edges. Table 7.2 gives the test pressure for vertically C.I. 1536-1967 designates their categories as under: Then it is tested under hydrostatic pressure and coated with coal tar as in the case of sand moulding. The pipe is taken out from the mould and sent to another process for annealing. Due to centrifugal force a homogeneous pipe is cast. In this method, the molten metal is poured in water cooled cylindrical metal mould, which is rotated at high speed. ![]() Centrifugal casting is the second method, which is sometimes called as Delov and process. This coal tar coating is done to protect it against corrosion. ![]() In the sand moulding, after casting, the pipe is cleaned, and dipped in a pot of coal tar and oil, after heating to about 300☏. Sometimes in sand moulding pipes are moulded in vertical position, which are called Pit Cast Pipes. Horizontal casted pipes are also called Mcwane Pipes. First method is ordinary sand moulding in which pipes are moulded in horizontal position. Cast-iron pipes are manufactured from best grey pig iron by two methods. These are highly resistant to corrosion therefore have long life-about 100 years. Cast-Iron Pipes:Ĭast-iron pipes are mostly used in water supply schemes. ![]() Following types of pipes are commonly used for conveyance of water: 1.
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