What You Need To Know About Compression Fittings - Today's Homeowner (2024)

As we wrote this column we were returning home from a remote radio broadcast that had aired from Rockford, Ill. Rockford is a large community (population 145,000 +/-) located about an hour west of Chicago. The radio show was going along pretty much “as usual” until we took a call from an older-sounding gal who phoned in with a special plumbing problem.

Before we could finish welcoming her onto the air she immediately proceeded to bark out several instructions, “Hold on, she said, I need to get the phone closer to the toilet so that you guys can hear the terrible racket that my it makes every time I flush”! Before we could respond she immediately proceeded to do just that. We could feel the silence as America waited anxiously to share in the lady-caller’s toilet-tank-symphony.

The lever dropped and the cycle began. Within moments the phone line transmitted the roaring howl of her troubled flush. After a laugh or two – and with all of the melodrama completely dispensed – we proceed to explain to the lady how easy and inexpensive the repair could be. We went on to describe that it would take a 59-cent washer, a screwdriver and about 30 minutes of her time to do the job.

We continued, “shut off the toilet water supply at the wall valve, flush to empty the tank and unscrew the top of the ball-co*ck valve to expose the culprit, dried-out noise-making washer”. She interrupted, “Wait a second, that’s too confusing for me”.

The point to our story is simple – even the most basic repair can overwhelm some folks. Could you imagine what her response would have been had we told the caller that her repair would involve soldering?

How’s that for a segway into a look at one of plumbing’s more user-friendly connecting devises – the compression fitting. It’s user-friendly alright, but a less than cautious DIY’er could easily end up with a leaky connection. We like to call this one the “don’t move it once everything has been tightened or it might leak” fitting. We’ll tell you why in a moment.

The compression fitting is a three-piece assembly that consists of a cap-shaped nut with female threads, a compression ring (that looks exactly like a simple wedding ring) and a seat section with male threads (usually an integral part of a faucet or fixture of some kind). The cap nut and the seat are screwed together causing the compression ring to squeeze tightly against both and the adjoining pipe. Thus, causing a “compressed or compression” type watertight connection.

Way back when, during our tenure as maintenance guys on the “Ark”, water pipes were all connected with threaded fittings. However, with the advent of copper pipe soldering became the common connecting method. By the way, soldering is not an easy task for even the most astute do-it-yourselfer. In the beginning there must have been quite a bit of resistance to soldering among those who were used to making pipe wrench connections. With the advent of the compression fitting a simple solder-free pipe wrench connection could again be made. No wonder compression fittings became so popular so quickly. Although compression fittings allow for the instant and easy removal and replacement of most household plumbing connections – without the need for a soldering gun or torch – there are a couple of drawbacks.

Once connected, the pipes traveling into and out of compression fittings must not be disturbed. Often, even the slightest movement can cause an otherwise watertight joint to leak as if it had never been properly tightened to begin with. It really is funny to watch a novice install a compression fitting. Then, immediately after tightening the connection, the newcomer will wiggle the newly connected pipe to insure that the joint is solid. This usually results in the instant creation of a leak. The trick with compression fitting connections is to leave them alone once the join has been achieved. Under-sink and other out-of-the-way fixture connections are where such fittings are most secure.

Although we strongly support the use of compression fittings at valves that are directly connected to half- and three-quarter-inch pipe, we take a completely opposite position on compression fittings used for quarter- and eighth-inch tubing – such as water supply connections between the wall valve (angle stop) and the faucet or toilet. Here we recommend the new high-pressure plastic and metal water supply lines. They sport the same threads used by compression fittings and they don’t leak – no matter how much you wiggle them.

Finally, keep in mind that reusing a compression fitting doesn’t always work. We frequently succeed at this endeavor, but the folks who make compression fittings say that each connection creates its own concentric shape and that reusing a compression fitting could result in a leaky connection.

To remove an existing compression fitting remove the cap nut and then use a fine tooth hacksaw to cut the compression ring off the pipe. Caution must be used to prevent slicing up the underlying pipe. And, good luck!

Further Reading

  • How to Replace a Kitchen Faucet
  • The Toilet Dilemma: Wax or No Wax?
  • Leaky Shower Door Repair
What You Need To Know About Compression Fittings - Today's Homeowner (2024)

FAQs

What are the basics of compression fittings? ›

Brass is the most common material for compression fittings because it provides strength and corrosion resistance without increasing costs. Compression fittings are made up of three basic elements: a compression nut or screw, the sleeve/ferrule, and the compression fitting body.

How do I know what size compression fitting to get? ›

1) To measure a threaded fitting measure the thread diameter at the widest point across the threads. For a non-threaded fitting measure actual insert opening diameter or tube being inserted. 2) Compare your pipe measurements to chart below to determine correct size compression fitting.

What are the pros and cons of compression fittings? ›

Because they don't require soldering, they make replacing connections quick and easy without worrying about hot work permits or fire watches. The only disadvantage of compression fittings is that they require manual tightening, and if they're too tight or loose, they can leak.

Do professional plumbers use compression fittings? ›

As a plumber, you are going to need to make compression fittings your best friend.

How tight do I tighten compression fittings? ›

Step 6: SECURING THE FITTING

Once that's done, go ahead and start tightening it. Your cue for knowing when they are tight enough is when you start to hear a squeaking noise as you are tightening, this is caused by the rotational friction between all the parts inside.

What is the most common cause of leaking compression fittings? ›

Improper installation

This will help establish a fully sealed and secure connection to the water supply. If the fitting isn't positioned correctly, you're guaranteed to have a future leak on your hands. You should also make sure not to overtighten a compression fitting as this can also cause leaks.

How many PSI is a compression fitting good for? ›

Compression Fittings Features

Working Pressure: 1/8, 3/16: 400 psi. 1/4, 5/16: 300 psi. 3/8, 1/2: 200 psi.

How do I know what compression I need? ›

A good rule of thumb to follow is: 15-20 mmHg: Great for daily wear, travel, and sports. They help improve circulation without being too tight. 20-30 mmHg: Great for sports recovery, daily wear, medical recovery, and to manage mild symptoms of varicose and spider veins.

What are the most common compression fittings? ›

Most compression fittings are made from brass and copper because these metals combine strength and resistance to corrosion without high costs. Plastic and stainless steel models are also available. Both brass and copper fittings make an excellent tool for joining copper pipes and plastic tubing.

What do you use to seal compression fittings? ›

Use pipe dope or plumber's grease when replacing the compression fitting. It's advisable not to use Teflon tape on compression fittings as it can keep the compression nut from screwing down enough to form a waterproof seal successfully.

How many times can you use a compression fitting? ›

Disassembly and Re-Assembly

It is important to note however, that compression fittings can only be disassembled and reassembled a few times before either the ferrules and/or the fitting body should be replaced, to ensure a leak-tight seal.

Should I use plumbers tape on compression fittings? ›

No, you definitely should not.

Can you trust compression fittings? ›

Absolutely. Compression fittings have stood the test of time. They are a proven and reliable method for connecting pipes, particularly in applications where it's not practical or possible to solder the pipes together. They're commonly used in both domestic and commercial plumbing installations.

Are sharkbites as good as solder? ›

Installing a sharkbite fitting is a convenient and quick-fix solution. But if you opt for a long-term solution, soldering is the best option due to its credibility and result. Copper pipes may last 50 to 70 years as long as it is installed properly and well-maintained.

What are the basics of compression? ›

Compression is a music production tool used to control the dynamic range of a sound: to decrease the difference in volume between its loudest and softest parts. This can be done by making the loudest parts quieter (downward compression) or the quietest sounds louder (upward compression).

What are the three main parts of a compression fitting? ›

Compression fittings are simple to install but require a wrench in most cases. They consist of three components: the sleeve, nut, and fitting body. All components work together to create a watertight seal.

What is the difference between Type A and B compression fittings? ›

There are two types of compression fitting, standard (British type-A/non-manipulative) and flare fittings (British type-B/manipulative). Standard fittings require no modifications to the tubing. Flare fittings require modification of the tubing with a special tool.

Do compression fittings need to be flared? ›

A flareless fitting, also referred to as a compression fitting, uses a single ferrule and a nut to make a connection, eliminating the need for flaring.

References

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