Installing Steel Pipe

Working with Steel Pipe

New water supply lines are usually copper or plastic, but if you need to repair or extend a galvanized pipe system, it makes sense to use the same material.

Almost all gas lines are black threaded pipe, which is installed the same way as galvanized pipe.

Measure carefully, keeping in mind that 1/2- and 3/4-inch pipe goes about 1/2 inch into each fitting. Then have a home center or hardware store employee cut and thread pieces to these exact measurements.

A more flexible strategy is to estimate your pipe and fitting needs. Then you can buy long pipes as well as a variety of nipples -- short lengths of threaded pipe ranging from 1 to 12 inches. Also buy extra couplings. When you come close to the end of a run, you probably can create the correct length simply by combining nipples and couplings.


About an hour to cut into a line and install several fittings and pipes

Hacksaw or reciprocating saw, two pipe wrenches (14-inch wrenches are a good choice), groove-joint pliers

Careful measuring and planning, firm tightening using a pipe wrench

Shut off water. If there is a nearby union fitting, you may be able to avoid cutting a pipe.

Threaded pipe lengths and nipples, pipe-thread tape or pipe joint compound

Step 1

Shut off water to the line. To tap into the middle of a line when there is no nearby union fitting, cut through a pipe with a reciprocating saw equipped with a metal-cutting blade or with a hacksaw. Unscrew the pipe on both sides of the cut.

Step 2

Before threading a pipe into a fitting, wrap the threads with several windings of pipe-thread tape. With the pipe end facing you, wrap clockwise. Or brush pipe joint compound onto the threads of the pipe end and the inside of the fitting.

Step 3

Twist on a pipe or fitting by hand. If it does not turn easily, the joint is not straight and the threads are crossed. Back up and try again. Then firmly tighten each pipe or fitting using a 14-inch pipe wrench. You may need a second wrench to hold the adjacent piece steady.

Step 4

Once the tee-fitting for the new line is installed, add a nipple and slip on the nut for the union, checking that the threads are toward the joint. Apply tape and install half of the union. Set the second half of the union in place and measure for the final section of pipe.

Step 5

Attach the second half of the union to the final piece and install. The union halves should line up so they can set against each other. Slip the union nut up and hand-tighten. Then fully tighten the nut with a pipe wrench to complete the union.

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