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Working with Steel Pipe

PEX, Plumbing - Directory January 25, 2005 Sonia


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Chances are if your home is more than 30 years old, you have some steel piping. This steel piping may be for plumbing supply lines or a gas piping system.

The material of choice for plumbing these days, however, is plastic or copper. Copper, either rigid or tubing, is by far the most popular supply line used in the last three decades in residential systems. Plastic has pretty well replaced iron pipe for residential drain, waste and vent systems.

The traditional gas supply line, downstream of the point of delivery, was supplied with an average pressure of 7 inches water column (1/4 psig) by means of Schedule 40 (“black iron”) steel pipe. Black-iron piping systems are expensive to install due to the number of couplings and fittings needed, as well as the increased labor cost. These days many gas companies are also going to semi-rigid tubing, rather than rigid steel supply lines. And a new flexible stainless steel piping system, called corrugated stainless steel tubing (CSST) is fast gaining favor. This, however, may only be installed by professionals.

You may, however, wish to repair older supply lines in your home with the traditional materials, or extend propane gas or natural gas to new things like exterior kitchens, barbeques or gas logs in the fireplace. CSST can’t be used in contact with the ground, unlike black iron and galvanized steel pipe, which are both readily available at most hardware stores and building supply houses. Both are worked and installed in the same basic manner. One of the advantages is these pipes are available in a range of pre-threaded lengths, along with the fittings needed to join them. Also, many hardware stores will cut the pipe to length and thread the ends. One of the main disadvantages of working with either material is they’re relatively heavy in relation to other materials. And, being rigid, they aren’t as easy to install, as are semi-rigid and flexible tubings. Special tools are also required to work with steel pipes, including a pipe vise, cutter, reamer and threading die to match the size of the pipe. You can, however, often rent the tools needed.

 

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Both black steel and galvanized pipe are available at building supply stores in precut, prethreaded lengths. Some hardware stores will cut and thread to suit.

 

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Both materials are used with cast fittings and couplings to join sectionsor lengths as needed.

Cutting and Threading

If you can’t purchase pre-threaded pieces in the lengths needed, you will need to cut and thread the pipe. It’s extremely important the cut be square and even. First secure the pipe solidly in place in a pipe vise, or solid bench vise. Then use a rotary pipe cutter to cut to length. To use the cutter, position it on the pipe and tighten the knurled handle just until the cutting wheel touches the pipe. Apply a bit of cutting oil, or even light automotive oil and tighten the tool slightly on the pipe. Make a couple of turns around the pipe. Turn the knurled handle to further tighten and make a couple more turns, again lubricating with oil. Continue tightening, turning and lubricating until the pipe is cut through. Use the reamer to smooth the inside cut edge of the pipe.