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How To Design And Install Plumbing
Calk Joint on Cast Iron Water Main. Cast-iron water main is joined by means of molten lead, which is substantially calked after it has been allowed to cool. The joint usually is made in a horizontal position, although vertical joints are not uncommon.
Horizontal Calk Joint. The first step in the process of making a horizontal calk joint on water main is to dry the hub thoroughly and wipe it clean of foreign substances. It is also advisable because of the thickness of the metal, to heat the hub and bell ends of the pipe in cold weather, using a plumber's furnace for the purpose or igniting a small amount of hemp which has been placed in the end of the pipe. Moisture and cold material are liable to cause the molten lead to sputter and may cause an imperfect run of the lead.
The pipe must be laid in place and aligned properly so the joint will be evenly spaced. A single ring of twisted or braided hemp must then be yarned into the bell to prevent the lead from running into the pipe. After the hemp has been inserted and packed thoroughly, a pour rope of asbestos, or a roll made of plastic clay is applied to the face of the bell and must be provided with an exceptionally large well to allow the molten lead to enter the joint as rapidly as possible. The joint must be made in one continuous pour and requires a large amount of lead, and it is well for the mechanic to have a surplus amount of metal in the pouring pot in case difficulty is experienced.
After the joint has cooled sufficiently the pour rope may be removed and the joint can be calked. Inside and outside calking irons and a heavy hammer are used for this purpose. The inside of the joint must always be calked first so the ridge left by the pouring rope can be calked into the bell. The outside edge is also calked to complete the joint. The surplus metal, accumulated as a result of pouring the well, must not be removed—it is well to calk it and in this way drive it into the joint. It is difficult to crack the bell of the water main, and the mechanic doing the calking need not restrain the blow on the calking iron. After the joint has been completed it should be inspected for defect and then be tested with water pressure.
Vertical Calk Joint. A vertical calk joint on water main is made in practically the same manner as a vertical joint on cast-iron soil pipe except that only a single ring of hemp is yarned into the bell and the molten lead is poured in one complete run. The joint must be substantially calked to be effective.
