Part 16 (1/2)
CHAPTER XV
INSULATION OF PIPING TO ELIMINATE CONDUCTION, RADIATION, FREEZING, AND NOISE
PIPE COVERING.--Pipe covering is another important branch of plumbing. A few years ago heating pipes were the only pipes that it was thought necessary to cover. The ever-increasing demands made by the public keep the wideawake plumber continually solving problems.
The water running down a waste pipe, for instance, will annoy some people, and provision must be made to avoid this noise or to silence it. This is one of the many problems that the plumber must solve by the use of pipe covering.
PIPES THAT NEED COVERING.--First of all, the covering must be put on properly to be of high service. _Hot-water circulating pipes_ need covering to reduce the amount of heat loss. If the pipes and the tank are not covered, considerable more fuel will be needed to supply the necessary amount of hot water than if the pipes and tank were covered with a good covering. _Cold-water pipes_ need covering in places to keep them from freezing. They also need covering under some conditions to keep them from sweating. They are covered also to prevent the material which surrounds them from coming into direct contact with the pipe. _Waste pipes_ need covering to prevent them from freezing and to silence the noise caused by the rush of water through them. _Ice-water pipes_ are covered to prevent the water from rising in temperature and to prevent any condensation forming on the pipe. There is need for such a variety of covering that I have listed below some of them and the methods employed for putting them on the pipe.
Magnesia, asbestos air cell, molded asbestos, wool felt, waterproof paper and wool felt, cork, hair felt. These coverings come in the form of pipe covering with a cloth jacket. They also come in the shape of fittings as well as in blocks and rolls of paper, and in powdered form. Any thickness that is desired may be had. The pipe covering is readily put on the pipe. The cloth jacket is pulled back a short distance and the covering will open like a book. It can then be clamped on the pipe and the jacket pulled back and pasted into place. Bra.s.s bands, 1 inch wide, come with the pipe covering. These are put on and the pipe covering is then held securely in place. Practically all the coverings are applied in this manner and are made up in 3-foot lengths to fit any size pipe.
To cover the fittings and valves, the same kind of sectional covering can be obtained and applied in the same manner as the pipe covering. Plastic covering is often applied to the fittings and molded into the shape of the fitting. The plastic covering comes in bags and is dry. It is mixed with warm water to the consistency of thick cement and applied with a trowel. When the covering is put on the pipes and fittings, it should be done thoroughly to get satisfactory results. Each section of the covering has on one end an extra length of the jacket. This is to allow a lap over on the next section to make a tight joint. If the sections need fitting, a saw can be used and the covering cut to any desired length.
_Magnesia_ covering is employed mostly on steam pipes, especially high-pressure. This material can be had in the shape of pipe covering, in blocks, or cement.
_Asbestos air cell_ covering is employed to cover hot-water circulating pipes. It is constructed of corrugated asbestos paper. This material is manufactured in the sectional pipe covering or in corrugated paper form.
_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:
-------+-----------+------------- Size | Thickness | No. threads | | per inch -------+-----------+------------- 1-1/4 | 0.140 | 11-1/2 1-1/2 | 0.145 | 11-1/2 2 | 0.154 | 11-1/2 2-1/2 | 0.204 | 8 3 | 0.217 | 8 3-1/2 | 0.226 | 8 4 | 0.237 | 8 5 | 0.259 | 8 6 | 0.280 | 8 -------+-----------+-------------
Screw pipe work came into common use with the advance of modern steel structures. Some difficulty had been experienced in getting the cast-iron pipe joints tight and to keep the pipe so anch.o.r.ed that it would not crack. The screw pipe was found to answer all of the requirements of modern structures and therefore has been used extensively. The life of screw pipe is not as long as extra heavy cast-iron pipe. This is the only serious objection to screw pipe, which must be renewed after a term of years, while extra heavy cast iron lasts indefinitely. Screw pipe is never used underground. When piping is required underground, extra heavy cast-iron pipe is used.
PIPING
The pipe used in Durham work is galvanized extra heavy, or standard wrought-iron, or steel pipe. It is almost impossible to recognize wrought-iron from steel pipe without the aid of a chemical or a magnifying gla.s.s. To test the pipe to distinguish its base, take a sharp file and file through the surface of the pipe that is to be tested. If the pipe is steel, under a magnifying gla.s.s the texture of the filed surface will appear to be smooth and have small irregular-shaped grains, and there will also be an appearance of compactness. If the pipe is iron, the texture will have the appearance of being ragged and will show streaks of slag or black.
When screw pipe is cut there is always left a large burr on the inside of the pipe. This burr greatly reduces the bore of the pipe and is a source of stoppage in waste pipes. After the pipe is cut this burr should be reamed out thoroughly. One of the strong points of screw pipe is the strength of each joint. Care should therefore be taken to see that perfect threads are cut on the pipe and that the threads of the fittings are perfect. The dies should be set right and not varied on each joint. There should be plenty of oil used when threads are cut so that the thread will be clean and sharp. The follower or guide on stocks should be the same size as the pipe that is being threaded, otherwise a crooked thread will result. If a pipe-threading machine is used, the pipe is set squarely between the jaws of the vise that holds the pipe in place.
When cutting a thread on a long length of pipe, the end sticking out from the machine must be supported firmly so that no strain will come on the machine as the pipe turns. It is necessary to cut crooked threads sometimes on the pipe to allow the pipe pitch for drainage or to bring the pipe into alignment where fitting would take up too much room. To cut a crooked thread on a piece of pipe, simply leave the follower out of the stock or put in the size larger. The dies not having a guide will cut a crooked thread.
Piping should be run with as few threads as possible. With a thorough knowledge of and the intelligent use of fittings, a minimum number of threads will result.
The pipes in a building are run in compact parallel lines in chases designed especially for them. The tendency is to confine the pipes to certain localities as much as possible. This makes a very neat job and in case repairs are needed, the work and trouble incurred will be confined to one section.