Plumbing pipe made from galvanized or bare steel can be threaded to mate with other threaded pipe via fittings. Specialized tools are available for cutting and threading these materials, and should be used for these jobs. The exception is that steel pipe can be cut with a reciprocating saw or hacksaw, however, a tool called the Ferrous Pipe Cutter works best. Other tools for this job are a pipe vise, pipe reamer, ratchet threader, and a machine called a mule.
Ferrous Pipe Cutter: This tool is designed specifically for making clean fast cuts in lengths of steel pipe. It looks like a heavy duty c-clamp, with rollers in one jaw and a cutting wheel in the other jaw. The cutting wheel side is attached to the end of a screw that adjusts to your piping diameter.
The bigger the diameter pipe, the harder it is to cut. Most home steel pipe plumbing will be less than two inches in diameter, but if you have to cut anything bigger than that, it is best to send it to a specialist shop, where they have industrial strength equipment. Ridgid and Reed are the two most common brands of pipe cutters.
Pipe Vise: A regular machinist’s or woodworker’s vise cannot easily accommodate round pipe stock, so for holding pipe, specialized pipe vises are available. They have either arced jaws or a chain to grip the pipe and hold it in place for cutting or threading. They are designed to open and close quickly and can be seen mounted on the back bumper of many a plumber’s pick-up truck.
Ratchet Threader: This tool has a ratcheted head holding an interchangeable cutting die, attached to a long handle for creating the torque necessary for making threads in a pipe. The dies are different diameter sizes to accommodate various pipe sizes, usually from ½ inch up to 2 inch diameter. You’ll also need some thread-cutting oil, for getting a smooth cut and protecting your dies from wear and tear. Some plumbers who use virgin olive oil as thread cutting oil swear it works better than commercially available cutting oil. One thing that definitely cannot be used is automotive engine oil, so don’t try that, you’ll just make a mess.
Pipe Reamer: After cutting threads in a pipe end, a reamer is used to remove any sharp edges and burrs. There are a few different types of reamer used. The one most used is a bevel cutter that can be fitted into a ratchet threader’s die head in place of the thread die. Another type is a hand reamer, which can be mounted in a brace drill. Either way, three or four rotations of the reamer should be enough to clear the pipe end of ridges and burrs.
Mule: This is a heavy duty threading and cutting machine used by professionals who specialize in working with steel pipe. It’s usually mounted in a truck, as it is much too bulky and heavy to be lifted by one man. It’s basically a big steel box with a big sliced chuck on one end and a tube opening at the other end into which the pipe to be cut is slid. Once the pipe is in place, the chuck is closed on it and a threading die is attached to it. The mule also has a built in pipe cutter and oiling mechanism.
Tripod: Another expensive tool for professionals, the tripod is a portable pipe cutting and threading work station sitting on three folding legs. The big, flat work surface can hold a pipe vise and other tools can be hung from it’s underside. One of the three legs has an integral rotational motor for the threading operation. Tripods can be rented by the day, which makes more sense for the average do-it-yourselfer.
Galvanized steel pipe has been mostly replaced by copper in residential construction, but it is still used as main water supply line piping between the water meter and the building, particularly if the line is near the surface, as plastic pipe will not withstand pressure from aboveground traffic as well.
A big downside of the material is that it will corrode and scale within five years if used in an area with high mineral content water. It is also hard to work with assembling fittings and threaded pipe in tight access areas inside of buildings where pipe wrenches are unwieldy. After working with steel pipe inside a house for any length of time, you will see why copper pipe is so widely used.