Molded asbestos covering is also used on hot-water pipes, and is manufactured in pipe covering or in blocks.
Wool felt covering is used mostly on hot-water pipes and makes one of the best coverings. It is lined with asbestos paper and covered with a cloth jacket.
Waterproof paper and wool felt is used on cold-water pipes and is made in 3-foot lengths. The covering is lined with waterproof paper and covered with a cloth jacket.
Cork.—A heavy cork covering is one of the best coverings for ice-water pipes, and a light cork covering is used for cold-water pipes. This covering comes in sections as other coverings, also in blocks and sheets.
Hair felt is used to prevent pipes from freezing. It comes in bales containing 150 to 300 square feet of various thicknesses.
CHAPTER XVI
"Durham" or "Screw Pipe" Work. Pipe and
Fittings
"Durham" or "screw pipe" work is the name used to denote that the job is installed by the use of wrought-iron or steel screw pipe. We speak of a "cast-iron job" meaning that cast-iron pipe was used for the piping. A completely different method of work is used when screw pipe is employed for the wastes and vents. When screw pipe is to be used or considered for use, it is well to know something concerning the various makes of screw pipe. Nothing but galvanized pipe is ever used. The value of steel screw pipe and wrought-iron screw pipe should be studied, and every person interested should, if possible, understand how these different pipes are made and how the material of which they are composed is made. In some places one pipe is better than another and a study of their make-up would enlighten the user and allow him to use the best for his peculiar conditions. The maker's name should always be on the pipe. The following table shows the sizes, weights, and thicknesses of screw pipe: