Two pipe wrenches opening a union nut in order to remove an old threaded steel pipe

How To Remove An Old Threaded Pipe (Just 4 Steps!)

After your first experience with threaded pipe, you’ll appreciate why this material is all but extinct in new installations. Cutting, threading, and assembling steel pipe requires muscle. Sometimes, when you’re trying to take old pipe apart, you’ll swear it was welded together.

If you home was built before WWII, its supply pipes are likely to be threaded steel. This doesn’t mean you have to use the same pipe for improvements or repairs. Special fittings let you break into a pipe line and add copper or plastic.

Let’s get started.

Here’s All You Need

Here are the basic things you need to successfully remove an old, threaded steel pipe:

  1. Time

    You’ll need about one hour to take apart four or five sections of pipe and fittings.

  2. Skills

    You have the skills to do this job if you can read follow these instructions, use a pipe wrench, and be ready to apply to some brute strength if necessary.

  3. Tools

    Two pipe wrenches, one hacksaw (with metal-cutting blades), and possible a propane torch.

Editor’s Note: This is the first of a 2-part series on threaded steel pipes. The next article in this series is titled, “How to Install a New Threaded Pipe (In 3 Steps!).”

Remove the Old Pipe in 4 Easy Steps

Actually, unless you run into problems with a stubborn joint, you might even have fewer than four steps.

1. Shut Off Your Water

Before you begin any project that involves removing or installing a water pipe, you should first, and always, shut off the main source of water coming into your home.

Start by turning of the main water shutoff valve
More often than not, the main water line shutoff valve will be located inside your home. Look for the wall that’s closest to the street because this is where your water supply usually comes in.

2. Unscrew the Pipe Union

Examine the way your pipe and fitting threads together. You’ll see that you can’t simply begin unscrewing them anywhere. Somewhere in every run of pipe is a union that allows you to unlock and dismantle the piping. See the photo and caption below for a description of a pipe union.

To crack open a union, determine which of the smaller union nuts the ring nut is threaded onto. With a wrench on each nut, turn the ring nut counterclockwise. When unscrewing pipe, use the second wrench to keep the fitting from turning while you unscrew the ring nut.

Once it’s unthreaded, you have the break you need and can start unscrewing the pipes from their fittings.

Three-quarter inch black pipe union - how to remove threaded pipe
This is an example of one type of pipe union. They allow two pipes to be connected together in a way that requires only one pipe to be turned when removing the union. There are 3 parts to a pipe union: (the nut, a female end, a male end).

3. Cut the Pipe if Necessary

If there is no union handy, you’ll need to take a more direct approach. Cut the pipe with a hacksaw fitted with a metal-cutting blade.

Important: Because you have cut the pipe, you will not have a threaded union to attach the pre-threaded nipple onto. The only ways to tie onto a cut steel pipe is to thread it (this is a pain, we’ll admit). A better answer lies in using a compression fitting which goes on the outside.

The pipe will need to be capped off before any water is turned back on.

Remove old threaded steel pipe using hacksaw
Example of a pipe being cut with a handsaw or hacksaw using metal-cutting blade.

4. Try This if the Pipe Doesn’t Budge

Stubborn joints should respond to heating (and loosening) the fitting with a propane torch. Then use a larger pipe wrench, or slip a piece of 1.25″ or 1.5″ pipe onto the handle of your wrench to help you increase its leverage.

A little show of strength and this extra leverage will help you release the joint from the threads.

Propane torch being used on stubborn pipe joint to loosen it
Although this photo shows a copper pipe, a propane torch used on the stubborn joint of an old threaded steel pipe will work just as well to loosen it.

Frequently Asked Questions

Can I replace my threaded steel pipe with a different material?

If you have good water pressure and can find no serious rust, there’s no need to replace your threaded still pipe with another material like copper. But if water pressure is low, aerators fill with rust, and leaks develop, then it’s time for a change.

Can I use penetrating oil to loosen a pipe joint?

Yes, this is a good alternative to using a propane torch on a steel pipe joint. Here are video instructions for using this method on different pipe materials.

How will I know my pipe is made out of steel?

Take a penny and scratch the surface of any suspected pipe. If the scratched area is silver-grey in color, it’s made of steel and a large magnet will stick to it.

Final Thoughts

For those in older, pre-World War II (pre-1940s) homes with steel water pipes, you should take time to give them a good once over. Examine them carefully using a flashlight.

If you see any signs of rust, corrosion, or leaks (it can simply be wet), a change in pipe material is in order. You certainly don’t want those materials invading your water supply. It’s the reason modern homes no longer use this material.

But take head, replacing a bit of threaded steel pipe can be fairly easy. However, if too much of it needs to be replaced, you’re best bet is to get a team of professional plumbers on the job.

Call 1-Tom-Plumber

We can help you repair, remove, or install any type of pipes and fittings. We will also immediately respond to any of your emergency plumbing, drain cleaning and drain clearing, or water damage problems. And we have specialists who excavate, repair, and replace broken sewer lines. Just send us a message or call us at 1-866-758-6237.

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