JOINTS IN SEWER

Bell and Spigot Joint The plain end of the pipe is known as spigot end and the expanded end is known as bell end. The Yarn is wound round the spigot end and a rubber gasket is placed tightly over the Yarn. The spigot end is now inserted into the bell end in such a way that it is properly set in position. Then the gap of the joint is filled up with molten lead by suitable pouring device. The lead shrinks on cooling. Then it is tightened by means of chalking tool and hammer.

Collar Joint Collar joint is recommended for joining the R.C.C. pipes and asbestos ce-ment pipes. Grooves are provided at both ends of these pipes. Before join-ing, the pipes are brought face to face and at the same level. A gasket or hemp is placed between the grooves of the pipes and a collar (made of concrete) is placed properly at the joint. The position of the collar is checked so that it may have same lap on both the pipes. Then the space between the pipes and the collar is filled up with cement mortar(I:1) and the surface is finished at an angle of 45°.

Expansion Joint The expansion joint is recommended for places where the elongation or shortening of the pipe may happen due to the change of atmospheric temperature. Here, the bell end is projected vertically to some extent for coupling with the flanged ring by nuts and bolts. Before starting the joint, the flanged ring and a rubber gasket is placed in position on the spigot end. Then the spigot end is inserted into the bell end and held in position by checking the level. Then the rubber gasket is pressed tightly between the annular space, by means of nuts and bolts to make the joint water tight. The rubber gasket will absorb the variation of length if caused due to the change of temperature.

Flanged Joint This type of joint is recommended for temporary work where the pipe line may be dismantled after work or it may be shifted. For this joint, the ends of the pipes should be provided with wide flange with several holes for nuts and bolts. While joining the pipes, a rubber gasket is inserted between the flanges and the nuts are tightened to make the joint watertight. This joint is not suitable in places where vibration or deflection is suspected.

Flexible Joint This type of joint is recommended for the places where the settlement of the pipe line may occur. For this joint, one pipe has spigot end with a beat and the other pipe

has socket end with spherical shape and it consists of several holes for nuts and bolts. During assembling, the spigot end of one pipe is inserted into the socket end of other pipe. A retainer ring is pushed to touch the beat. Then a rubber ring is also pushed to touch the retainer ring. A cast iron gland ring is placed in position and a cast iron follower ring is fixed with the socket end by nuts and bolts.

Threaded Joint This type of joints are recommended for connecting the G.I. pipes. Here, the ends of the pipes are plain with threads on outside. The joints require sockets which are threaded on inside. To make the joint waier-tight, either zinc point or hemp yarn applied on the threads. Then the socket is tightened so that the pipes are held firmly in position