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How To Design And Install Plumbing
Joints In Clay And Iron Sewer-Waste And Vent
The plumbing industry does not have as many skills associated with it as do other trades. It consists largely of joining pipe of various kinds and materials, incorporating in the completed system many scientific principles. A plumber must know what kind of joint to use for certain materials and be able to produce it and make it water- and air-tight.
The plumbing installation contains many noxious gases which would be detrimental to good health were they permitted to enter an occupied building through leaking joints. These gases affect the delicate breathing mechanism of the human body and therefore must be controlled.
Imperfect joints allow the liquid content of the waste pipe to escape and, in this event, property damage is likely to result. As a general rule soil and waste lines are concealed in partitions under the floor and, should a joint fail, painted walls and plastered ceiling will be damaged.
A leaking joint on a sewer or drain, installed below the surface of the soil, would allow sewage to enter the subsoil and contamination of drinking water might result. A joint of this kind also might allow soil to enter the drain and thereby cause stoppage of the line. One of the common causes of leakage of underground joints is the entrance of fine fibrous tree roots. Once the roots have gained entrance they spread quickly until the entire area of the sewer is filled. Correction of this difficulty can be accomplished only by digging up the drain and replacing it with new material.
All the joints which make up a plumbing system therefore must be made with care and when finished must represent careful workmanship. There are many kinds of joints that may be used for joining the pipe of a drainage system. The following are those which are used most commonly.
Cement Joint on Vitrified Clay Pipe. Fig. 28 illustrates a joint which is used to join vitrified clay pipe. The bell and spigot ends of the pipe must be cleaned of foreign material. After this has been done the spigot end of the pipe is inserted into the bell of the pipe to be joined. It is necessary to align the pipe and space the joint evenly so the cement mortar can be applied.
The cement mortar consists of equal parts of clean sharp sand and cement to which water is added until it forms a sticky mass. With the aid of a small pointing trowel the cement mixture is squeezed into the bell until it is completely full, then it must be banked on the pipe for about 2 inches and smoothed with the trowel.
