Fig. 2458.
Rust joints are employed upon very uneven surfaces, and for pipes for mains to go under ground. In former times this class of joints was much used in engine and boiler work, but of late years it has been to a great extent abandoned. In [Fig. 2458] is shown the method of construction for a rust joint for what are known as spigot and socket joints for pipe work. s is the spigot and p the socket. r r is a metal ring, bound over with either dry hemp fibre or tarred twine or rope. The remainder of the space between the pipes at a a being filled with a cement composed of
| Sifted cast-iron borings | 100 | lbs. |
| Sal-ammoniac | 1⁄2 | lb. |
| Sulphur | 1⁄2 | lb. |
but when required to set quickly, 1 lb. sal-ammoniac may be used. These ingredients are thoroughly mixed with water immediately before being used, and just covered with water when used intermittently. The cement is put into the space a a, in quantities sufficient to fill up about 3⁄4 inch in length of the annular space a a, and then caulked by being driven in with the tool shown in [Fig. 2459]. Cement is then again put in and the caulking repeated, the process being continued until the whole space is filled.
Fig. 2459.
In some cases (as in gas mains) the space a a is filled with melted lead, and when cold caulked with the tool described.