| 2-inch pipe, | 5/16 inches thick |
| 3 " " | " " " |
| 4 " " | 3/8 " " |
| 5 " " | 7/16 " " |
| 6 " " | 1/2 " " |
Cast-iron pipes are sometimes coated by dipping into hot tar, or by some other process. Tar coating is, however, not allowed in New York, because it conceals the sand holes and other flaws in the pipes.
Joints and Connections.—To facilitate connections of cast-iron pipes, short and convenient forms and fittings are cast. Some of these connections are named according to their shape, such as L, T, Y, etc.
Fig. 16.
DIFFERENT FORMS AND FITTINGS.
Iron Pipe is joined to Iron Pipe by lead-calked joints. These joints are made as follows: the spigot end of one pipe is inserted into the enlarged end, or the "hub," of the next pipe. The space between the spigot and hub is half filled with oakum or dry hemp. The remaining space is filled with hot molten lead, which, on cooling, is well rammed and calked in by special tools made for the purpose. To make a good, gas-tight, lead-calked joint, experience and skill are necessary. The ring of lead joining the two lengths of pipe must be from 1 to 2 inches deep, and from 1/2 to 3/4 of an inch thick; 12 ounces of lead must be used at each joint for each inch in the diameter of the pipe. Iron pipes are sometimes connected by means of so-called rust joints. Instead of lead, the space between the socket and spigot is filled in with an iron cement consisting of 98 parts of cast-iron borings, 1 part of flowers of sulphur, and 1 part of sal ammoniac.
Fig. 17.
All connections between Lead Pipes and between Lead and Brass or Copper pipes must be made by means of "wiped" solder joints. A wiped joint is made by solder being poured on two ends of the two pipes, the solder being worked about the joint, shaped into an oval lump, and wiped around with a cloth, giving the joint a bulbous form.