Black Iron Pipe Installation

Initial Step - Cutting and Threading the Pipe

Begin by securely holding the pipe in a pipe vise mounted on a stand, then use a pipe cutter equipped with rotary cutting blades to cut the pipe. Employing a high-quality cutting oil is advisable to preserve the integrity of the pipe cutter.

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After cutting the pipe to the desired length, smoothen or deburr the end to eliminate the sharp ridge formed during cutting. Apply ample cutting oil to avert any damage to the cutter and the threads. Placing a large piece of cardboard or plywood under your cutting area can save cleanup time later. Alternatively, use a bucket with a large screen strainer beneath your cutting area to collect excess oil for reuse.

The threading process is essential for proper connection. You might be fortunate to find a pipe of the required length at a plumbing store. Threading is achieved using a pipe threader. Select the appropriate die for the pipe size. Place the die over the pipe end, and rotate the handle by half turns to cut the thread. Continually apply quality cutting oil to safeguard the die. Continue threading until the die’s width matches the thread. The thread is tapered to ensure a snug fit. Stand the pipe upright to clear any cuttings and wipe the threads clean, being cautious of the sharp threads.

Next Step - Connecting the Pipe Fittings

Connecting black iron pipes necessitates fittings and connectors. For gas line installations, always use Teflon tape or pipe joint compound on the threads to prevent leaks.

If opting for pipe thread sealing tape, wrap it around the threads and insert the pipe into the fitting. Ensure you wrap the Teflon tape clockwise, viewing from the pipe's end. Wrap the threads at least four times but not exceeding six or seven times.

Alternatively, you could use a pipe joint compound, also known as pipe dope, to ensure a tight connection. Apply pipe dope with a brush, a small piece of wood, or a rag. Smear it on the pipe’s threaded end and inside the connection fittings before attaching them. The compound dries and expands slightly to create an airtight seal where applied.

Hand tighten the pipe, then use two pipe wrenches—one on the pipe and the other on the fitting—to secure the connector. If the pipe appears too loose, you might need to re-cut it. Read more.

Essential Black Iron Pipe Fitting Techniques

I often hand tighten the connections before adding a small nipple to the elbow, which I then tighten until I can no longer do so by hand. When connecting longer pipes, ensure to hold the interior with a wrench while tightening the exterior to prevent any movement. Using Pro Dope, I ensure the joints are tightly secured, which helps avoid leaks. Call (713) 812-7070 for home service and repair needs.

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Author: ddbbp (KS)

I had a plumber install some 1/2" black iron pipe for a water heater. I noticed the joints have about five threads showing, while others have fewer. Is there a standard for exposed threads on properly tightened joints? Does 4-5 threads indicate it's not tight enough? (p.s.- there is no odor, and I soaped the joints and found no leaks, but the exposed threads concern me!)

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Author: North Carolina Plumber (NC)

If it were leaking, I would be concerned. Since it's not, I wouldn't worry about it. If he threaded the pipe on site, like I do, some lengths might be slightly different. There might also be mixed fittings from different manufacturers.

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Author: ddbbp (KS)

The material used was pre-threaded nipples, fittings, and pipes from the manufacturer. So is five threads showing too many?

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Author: bernabeu (SC)

I'm not sure if there's a hard rule about exposed threads, but there should be seven threads total into the fitting for pipes sized 1/8" to 2" NPT/IPS. Check inside any threaded fitting to count.

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Author: ddbbp (KS)

So you’re saying that if it's not leaking or smelling, I shouldn't worry about having five threads exposed?

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Author: bernabeu (SC)

There are indeed rules about exposed threads. Your issue is that you can't know how many threads are inside the fitting or how tight the connection is. Typically, it should be four turns by hand, then two turns with a wrench, totaling seven turns. Did an inspector check the installation? If not, why wasn't it inspected?

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Author: ddbbp (KS)

This was installed over a year ago without an inspection because it was part of a water heater replacement, limited to the piping between the shutoff valve and the heater’s gas valve. As long as there are no leaks, should I be concerned?

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Author: hj (AZ)

No, and why did you wait a year before worrying?

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Author: ddbbp (KS)

I just didn’t notice it until recently.

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Author: packy (MA)

You have to consider that gas pressure is only measured in ounces, unlike the PSI pressure of a water main. While a hand-tight joint isn't ideal, it does often make a leak-proof gas joint. During a recent gas piping job, I achieved a 5 PSI test without leaks, even with a hand-tight joint. Don’t be overly concerned about your installation.

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Author: hj (AZ)

The fact that your house is still standing answers whether the joints are safe.

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Author: Pipe runner (AZ)

Post a picture of the work done, and I can tell you if you should be concerned.

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