Note.—Cast iron was formerly entirely employed for steam pipe, but now it is never used for high pressures.
While lead and iron pipe have taken the place of the old log pipes of former days for carrying water and sundry purposes, there are still uses for which wooden pipe is better adapted than any of the metal pipes; a new kind of wire wound wooden pipe has been made. Each length is built up of staves, wound with galvanized steel wire under tension. The sizes are made 2 to 8 inches internal diameter. The staves are kiln-dried, 7⁄8 inch to 11⁄2 inch thick. Joints are made with a male and female socket on the small sizes, and a sleeve and butt joint on the larger sizes, 8-inch pipe of this type, wound with No. 4 copper wire, has been tried, where acid water rapidly destroys ordinary pipes, with excellent results. This pipe has been tested to 500 pounds pressure, it is lighter to handle and is not so liable to burst as cast iron.
The proper anchoring and supporting of large steam mains is important. It is preferable to allow the system to expand in the proper direction without stress and at the same time avoiding vibration. The illustrations will give an idea of the method used in supporting pipes and allowing for expansion. Fig. [657] shows a wall bracket upon which the rollers supporting the pipe and allowing for the expansion and contraction are attached. Fig. [655] shows a bracket with an adjustable single roll, which may be adjusted to suit the pitch of the pipe at the same time allow the pipe to expand.
Fig. [655] shows a bracket with one adjustable roll designed for main steam pipes. This is an elaborate device but would be appreciated in buildings where everything is wanted to make up a strictly first class line of details.
Fig. [657] represents an extension of the same idea in which one bracket is made to carry two lines of pipe smaller than the one shown in the preceding illustration. Fig. [656] is a support made of one inch round iron and answers every purpose where all of these designs of pipe hangers permit of free expansion and contraction of the pipes.
It is bad practice to support the main steam pipes over boilers by hangers from the building as the building may settle in a different degree from the boiler hence the steam pipes are not properly supported, i.e., they are either strained unnecessarily by the strain upon the hangers or they are permitted to support themselves; it is better to support them by iron props underneath, made by screwing a flange upon the end of a piece of pipe of proper length and having a wrought iron crotch with thread and nut for adjustment inserted in the upper end.
The flange on the prop rests upon the boiler walls while the crotch fits the pipe and by means of the nut any desirable elevation of the steam pipe may be secured. For when the boilers settle as they will the pipes and connections all settle together.
Figs. 658-666.