I Don't Trust Compression Fitting Valves

alexjag33 · Oct 4, 2008

Hi all.

I'm about to install a new faucet. The guy at the Home Depot recommended that I use shutoff valves with compresion fittings that fit on 1/2" copper pipe. I have hot and cold copper pipes (1/2") coming out of the wall. So far so good.

I took a test piece of 1/2" pipe and tried to put the valve on to see how the compression fitting works. I was not impressed. The pipe is all loose- I could pull it out easily, even if the nut is tightened.

My test fitting looks much like the diagram here: http://www.naturalhandyman.com/iip/infplumb/infcomp.html

My steps up to this point were:

1. Put the nut and ring on the pipe, with the nut behind the ring.
2. slide the pipe onto the valve
3. Tighten the nut.

Why is the pipe loose? Am I missing something obvious? Can this type of connection be trusted?

Jimbo · Oct 4, 2008

Compression fittings are SUPER reliable.

Use this procedure:

1. bottom the pipe into the socket of the valve
2. slide the ferrule ring up snug against the back of the valve.
3. ensure that (1) & (2) do not move out of place while you
4. bring the nut up, hand tighten, then 1/2 turn with wrench. at this point you should be able to feel that the ferrule is starting to "grab". Make sure the pipe does not pull back. Tighten another 1/2 turn. By this time, the valve will probably stay in postion and not move, but you could turn it on the pipe if grabbed forcefully by hand. Now go about 1/2 more turn and at this point, the valve should not be able to move around by hand. There could be plus or minus 1/2 turn or so variability, but you get the idea.

Naturally, you need to be starting with a fresh, undamaged pipe. If you are reusing a pipe which previously had a compression fitting on it, that brings up some issues, but is USUALLY doable. Sometimes not.

Take it apart and give us a picture of the ferrule on the pipe when you take the valve off.

Sponsor · 2022-01-29T12:20:58-0800

Ian Gills · Oct 4, 2008

I am at London Heathrow Airport on my way to South Africa, Zambia and Malawi and here I am checking the forum. How sad is that?

I prefer to use brass nipples and then screw-on angle stops but compression fittings are fine too as long as they are not used behind a wall.

I always have very slight leaks after I install compression fittings which I normally fix by tightening just a 'little' more. So check for leaks that may happen very slowly.

hj · Oct 4, 2008

compression

You might have chosen a better article to cite. He is completely offbase as to the "ease" of removing a compression valve, as ANYONE who has ever tried to slide the nut and ring off without a special tool will tell you. I do not know why yours was "loose" but the normal thing is that it slides onto the tubing with a fairly snug fit. Then adequate tightening seals the valve "PERMANENTLY", until it is time to remove it. Maybe the "super handyman" who wrote the article has never been taught how to install a compression valve properly. IF so, then a more complicated way of attaching the valves WOULD be the way to prevent leaking.

MaintenanceGuy · Oct 4, 2008

Home depot sells a compression fitting that includes a brass tube you insert into poly tubing to stiffen poly so the fitting is supposed to be okay for both poly tube and copper. On these fittings, the compression ring is captive inside the compression nut and can't be removed. I've never used these on poly but I have used them in a pinch on copper and had a lot of trouble with them.

If you're using these combo fitting from Home Depot, that may be your problem.

hj · Oct 4, 2008

fitting

Those are not fixture compression valves, so it does not apply to this discussion.

Ian Gills · Oct 4, 2008

I am a little concerned that some of our members are posting at 5-9am on a Saturday morning. Go back to bed.

I have an excuse because I am in a different time zone.

Good news about the bailout yesterday though.

hj · Oct 4, 2008

early

So are they. Maybe it is 9:00 p.m. where they are. Now the Wall Street guys have to figure out how to steal 700 billion dollars, but I think they had enough experience the first time that they will be able to do it. A few multimillion dollar bonuses and golden parachutes should help.

Ian Gills · Oct 4, 2008

Well, one consequence of the financial crisis is that I will be using Mighty Putty and Drano for all my plumbing needs now. Now where did I put that flexible rubber P-trap?

Ian Gills · Oct 4, 2008

Here it is:

Oh the joy when I first moved into my first American house and was greeted with one of these under the kitchen sink.

I knew I was in for a ride and have been ever since.

God Bless America! The Land of the Rubber P Trap.

alexjag33 · Oct 4, 2008

Threads

Do the threads on the valve need pipe joint compund or tape? I read different articles, and some say to do it, and some say to avoid it. Who is right?

I also read somewhere else that says that the ring itself should have some compound, and not the threads. What about this?

This is why we newbies are always so confused!

Terry · Oct 4, 2008

Do the threads on the valve need pipe joint compund or tape? I read different articles, and some say to do it, and some say to avoid it. Who is right?

You haven't asked me yet.
The answer is on the box.
A little light oil can go on the threads.

Here's the kicker though. They are manufactured with a little light oil on the threads already.

We just slid them on, and tighten them up. We replace maybe a dozen every week. But then we are plumbers, and not handymen.

I've been doing it this way for over 34 years. It's not that hard.

alexjag33 · Oct 4, 2008

!

Ian Gills said:
I am a little concerned that some of our members are posting at 5-9am on a Saturday morning. Go back to bed.

HA... Saturday's when we (who are neither plumbers nor handymen) have a whole day to make mistakes and try new stuff. For me, it's a basement remodel. After 2 years of Saturdays of making mistakes, I'm now in the final stretch!

alexjag33 · Oct 4, 2008

Terry said:
You haven't asked me yet.
The answer is on the box.
A little light oil can go on the threads.

Have you ever put pipe joint compound on the ring itself, Terry?

Jimbo · Oct 4, 2008

I may be in a minority of one, but I tend to put a very light brushing of tefon paste on both the threads and the ferrule. I have take apart some that I knew I did 10 years ago, and they came apart easily, which is the point. The drop of oil does the same thing, and is probably the recommended way to do it.

Terry · Oct 4, 2008

Have you ever put pipe joint compound on the ring itself, Terry?

Of the hundreds we do, thousands maybe? I did try it once.
Compression works well though.
I don't see the point of introducing something messy.
If it ain't broke, why fix it?

I do use pipe dope on tapered threads,
that would be like a pipe nipple in the top of a water heater, a shower arm on the wall side, or a pipe nipple between a galvanized 90 in the wall and a FIP angle stop.

I don't use tape or dope on water heater flex, flexible connectors, washing machine hoses, garden hoses or compression fittings.

Master Plumber Mark · Oct 4, 2008

Grease it up with pipe dope

Terry said:
Of the hundreds we do, thousands maybe? I did try it once.
Compression works well though.
I don't see the point of introducing something messy.
If it ain't broke, why fix it?

I do use pipe dope on tapered threads,
that would be like a pipe nipple in the top of a water heater, a shower arm on the wall side, or a pipe nipple between a galvanized 90 in the wall and a FIP angle stop.

I don't use tape or dope on water heater flex, flexible connectors, washing machine hoses, garden hoses or compression fittings.

Terry, I beg to differ here...

The compression stops are the best.....
but I prefer useing the pipe dope on them..

I do no tlike hearing that pipe and nut squeak or make a squelching sound when I tighten it down..

that sound literally makes me wince......

I would much prefer adding my Oatey pipe dope to the
equation becasue I know I will not be called back out to that job becasue of a leak on that ferrul..

a little bit of pipe dope dont hurt nothing. and I have notices with the pipe dope that the fitting seems to compress down further than with out it......

My motto is .....

Grease it all up and then let god decide wether it is supposed to leak or not....

...

hj · Oct 5, 2008

compression

My routine for the past 55+ years. Open the box. Remove the valve from the box. Slide the valve onto the copper tube which has be cut to the right length. Tighten the compression nut. Fill out the invoice after verifying that it is not leaking. Leave the job.

Sandpiper Plumbing · Oct 19, 2008

I too dope the outside of the ring and put a spot of dope on the threads because I don't like the squeek when tightening. I was taught "dope all unions" and a compression joint is just another union (not technically but, you get the point). I've had dry compression joint leaks but I've never had a leak on one that I've doped.
Hercules Megalock by the way is our dope of choice...good stuff.

Bill Arden · Oct 19, 2008

I Don't Trust Compression Fittings

They always seem to loosen up after several years as the pipe compresses from vibrations and movement.

I like those braided stainless steel hoses with the pre-made rubber washer ends.
They are flexible enough to form a loop.

I Don't Trust Compression Fitting Valves

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