Using brass pipes for plumbing

Brass pipe is an alloy of copper and zinc. When the proportions are about equal, the pipe tends to corrode in spots, so all good brass pipe now made is 67% to 85% copper and the rest is zinc. The best grade is 85% copper and is called red brass pipe. Water, unless soft or containing ammonia, has little effect on brass pipe.

Galvanized steel and wrought-iron pipe are less expensive than brass but lack several of its advantages. Because it does not rust, you can use a size smaller than steel pipe without losing water volume. Its interior remains smooth and causes less friction. Brass is also easier to thread and bend than steel pipe.


Brass pipe is made in the same sizes as steel pipe, from 1/8" to 12". Extra strong brass pipe is made in all but the largest size. These sizes are: 1/8", 1/4", 3/8", 1/2", 3/4", 1", 1 1/4", 1 1/2", 2", 2 1/2", 3", 3 yr, 4-, 5", 6", 8", and 10".


Brass pipe is used for all plumbing but is particularly good for the hot-water distribution lines. Hot water rusts steel much faster than cold water does. Also, brass pipe on hot-water lines does not colour water red as steel pipe often does. Naturally, it lasts longer.


All fittings for brass pipe should be of heavy cast brass. When iron fittings are used with brass pipe, the contact of the dissimilar metals is conducive to electrolytic decomposition of the iron fittings. A full variety of elbows, Ts, reducers, couplings, unions, and combinations are manufactured, sufficient to provide for any contingency. In addition, many fixtures are nickel-plated or chrome-plated and present a very neat appearance. Exposed brass pipe can also be plated to match fixtures.

How to install

Brass pipe generally comes in 12-foot straight lengths. If stored for any length of time, it should be kept where it will be uniformly supported —on the floor or on a long shelf. It should not be hung over a couple of nails or pegs so that it may sag as it then becomes difficult to straighten and work with.

Like galvanized steel pipe, brass pipe is threaded at each end and screwed into fittings or couplings. Refer to the section on Steel Pipe for the method of installation, as brass pipe is handled the same way except for a few slight differences, discussed below.

Brass pipe is softer than steel or iron pipe and is easily marked or marred by ordinary pipe vises and pipe wrenches, so friction clamps and friction wrenches should be used. Iron-pipe dies should never be used for threading brass pipe. Special brass-. pipe dies should be secured and used. They will insure good, tight screw-thread joints in brass-pipe plumbing.

This necessity for using special tools to insure good work with brass might induce amateur plumbers to avoid using a little brass pipe if the special wrenches and dies cannot be borrowed. If you have to buy several extra tools you will not use often, there is no economy in using brass pipe just because it might prove a little more satisfactory in certain cases. The professional plumber will have all the various tools needed to work with steel pipe, brass pipe, cast iron pipe, lead pipe, and copper tubing, but the amateur had better stick to the one or two kinds his equipment will handle.

Do not forget to ream brass pipe after cutting it. All water pipe should be reamed after it is cut, whether it is brass, wrought-iron, or galvanized steel. It is bad plumbing to install pipes of the proper size and then reduce the bore at some fittings by failure to remove burrs made while cutting some of the pipes.


Clamp the brass pipe in a vise, using friction clamps. Do not let the end of the pipe project more than about 6" from the face of the vise, the easiest working distance.

The less it projects the better, for it makes the pipe stiffer in resisting the strains of threading.

See that the dies are set to the correct gauge mark, so that they will cut a thread to exactly standard size. Fittings are tapped to standard thread, and the thread cut on the end of pipe must match. Scrape or blow out any chips or dirt that might have been left from the last threading operation.

Slip the die on the pipe and start the thread. If the dies are hard to start, jerk a little, but only at the start. After a few revolutions, if the dies have caught, it will become difficult to revolve the stock with one hand. So use both hands and pull slowly at first. The thread will cut steadily, with an even resistance to the pull. If the resistance eases up suddenly, that means the dies have not caught, and the threads have been stripped. You will have to start over.

Lubricate the die while cutting a thread. Use plenty of cutting oil and apply more after every two threads. Reverse the stock occasionally to break the chips. Do not make too many threads. Only so many will screw into the fitting and cutting several more than that merely weakens the pipe beyond the fitting. About 5 to 8 perfect threads are usually enough. Stop cutting threads when the pipe end shows flush with the face of the dies.

Bending brass pipe

Generally it is not advisable to try to bend pipe. To change direction you should insert elbows of different angles. But as brass pipe is softer than iron or steel pipe, there may be cases where it will be satisfactory to bend it. Select a piece of soft pipe. If it is not soft enough, anneal it by heating it to a dull red at the place where the bend is to be made, and then bend it. If a large, easy bend is required, bend it around something large and round like a metal garbage can or a hot-water tank or a large tree. Do not bend over a sharp edge as the edge will kink the pipe. Bend a little at a time and never twice on the same spot. Then you will have an easy bend that is neither seriously flattened nor kinked.

Allowance for expansion

Brass pipe expands more than steel or wrought-iron pipe and therefore more clearance must be allowed, especially as brass pipe is often used for the hot-water supply lines. In private homes it is unlikely that the expansion of brass pipe will cause difficulties. A pipe 10 feet long expands slightly less than 1/4", so a pipe running from the basement to the second floor will not need much clearance. However, on lines longer than that, you should take care that one end is not too securely anchored, so that expansion can take place there when very hot water rushes through a pipe and heats it considerably.

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