Quick question regarding compression fittings on copper water supply lines.
Case #1) A few months ago I had to replace a shut-off valve under the sink that would no longer shut off completely. The previous fitting (1/2″) was a compression type so that’s what I replaced it with. There was a very small leak – like one drip every 30 seconds or so – and tightening didn’t make it go away, especially since the package expressly forbids over-tightening. I left it for the time being and noticed that the drips became less frequent. After about 3 days they stopped entirely.
Case #2) I just did an emergency replacement of our hot water heater and replaced the rigid connections with flex connections that included 3/4″ compression fittings. Upon testing, one of the two fittings had a small “ooze” leak. I tweaked it a little tighter and it made no difference. But it, too, simply went away after about 30 minutes.
So my question is; Is this SOP for compression fittings? Did I do anything wrong? Should I lay awake at night wondering if the fittings that now seem fine will suddenly start leaking again when I’m away? This DIY’er would like a little peace of mind. Thank you.
Replies
First I find that just a small dab of joint compound on the threads on the body and on the furle ring. That seems to help lubricate them so that they will tighten up.
If they weep using an 1/8 turn will stop that.
And I have replaced a number of stop valves that where installed with compression fittings. I have not tried to remove the old ring so I reuse that and nut.
But I have found that on some of them there is too much pipe stickying out and I need to trim that off a little.
William the Geezer, the sequel to Billy the Kid - Shoe
I use "gel" toothpaste (that has no grit at all), to lube the ferrule and threads. Any extra just washes thru the pipes and is not harmful if you drink it.
The gel is also good to lube the o-ring on a whole-house type water filter housing. Makes tightening and losening much easier.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
The valve under the sink has fine threads that usually do not need teflon tape. If the supply line goes in fairly straight the compression sleeve should stop water here. At the hot water heater the threads are coarse and need two wraps of teflon tape or pipe dope.It is possible you have a poor fitting or flex connection, try the teflon tape first before returning the fittings.
mike
A true compression stop has compression 1/2" supply side input and usually a 3/8 compression on out to fixture. As you said neither use tape, the ferule is the seal on input side and if using pex/copper or similar the plastic/brass ferule is the seal on output side.
If using one of the made-up stainless or flex lines (risers) it has an internal cone part that accomplishes the seal. Normally overtightening any of these is a bad thing.For those who have fought for it Freedom has a flavor the protected will never know.
I ALWAYS squirt WD-40 on the ferrule - otherwise you get that SQUEEEK on the last turn that lets you know the brass is galling and won't seal.
Plus I like the taste
Forrest
Fish oil is soo tasty...
and healthy, too.
When reusing the ferrul/nut, I find it best to wrap the ferrul with teflon tape to stop the squeak and fill the gaps.
The original plumber on this house loved to cut the line just high enough to install the comp fitting... bastidge... can't even flame a hard fitting to change it out.
I hate compression fittings because the replacement is always suspect.A La Carte Government funding... the real democracy.
Never had much fun with compression fitting until I used some pipe dope, after that no more problems.
But you should check the fitting when you get a chance to make sure it is not dripping because it will make a mess of the cabinet in no time!
I second the use pipe dope. I just replaced our water heater and the stainless steel flex lines had rubber-like washers, not really compression fitings. The instructions called for hand tight and then 1/4 turn. Just did not seem right, so honked down and leaked.
At around midnight I broke the cardinal rule of plumbing work, do not screw with it if the plumbing stores are closed unless you stock at least two of everything possible in the plumbing aisle. After cleaning connections, relubing with the pipe dope and not overtightening it was fine.
The fittings with the washer are much different from standard iron pipe and compression. A liberal application of Teflon tape can prevent proper seal, honking down can deform the washer beyond proper sealing. This washer differs from the compression ring in how it works (actually more like hose bibb fitting with washer).
Hope that helps.
Thanks all for the suggestions, especially when it comes to pipe dope. Now, just to clarify, by "pipe dope" you are refering to the creamy stuff that you also use on NG fittings & black pipe threads, correct? or is that something different?Any explination for why the micro-leaks just fade away? What's going on there? Is the brass morphing into a better "seat" or is the micro leak filling with micro crud and sealing itself?Curious....
I use a yellow version from True Value, White Seal, and Rector Seal. The Rector Seal has powdered Teflon. All three are good and I am sure there are others. But yes it is the stugg you described. Sometimes a weeping joint will "heal" by calcification of the water coming through. I hate to count on that.
I am not a plumber but do a lot of repair and remodelling. So the advice is pretty much on a money back basis. (;-)
I could in theory see a hot water line "morphing" through expansion and contraction developing a tighter leakfree fit. But what the heck do I know, wisdom seems to come pretty easy after a couple of martinis.For those who have fought for it Freedom has a flavor the protected will never know.
Speaking of braided stainless steel water heater supply lines...
I had loads of black scale coming out of the tub spout and nowhere else. Turned out to be the rubber deteriorating inside the 3 year old stainless flex. The high rate of flow to the tub dislodged the crud.
Replaced with copper flex. I don't use stainless any more.
OB
Ya got me thinking ( always a bad thing) I wonder about why we don't have quick connects like air hoses and compressers use seen as potable supply lines and stuff?
Seems like a good idea on the surface.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
A lot of widespread faucets use a type of them now for connecting the faucet to the handles. Besides that, I don't know that it's really worth it, it's a slightly weaker fitting, and the frequency in which you remove the things probably wouldn't be worth the convenience.
The stainless ones I used are not the braided, they are the bendable "armadillo looking" ones. The ones I took off were similar copper ones. They had some weeping leaks over time and had some corrosion build-up. We have a lot of acid here in our ground water and a lot of copper gets eaten up. {clarification: the leaks were at the fittings, not the pipe}
For those who have fought for it Freedom has a flavor the protected will never know.
Edited 12/25/2008 12:32 pm ET by rasconc
A number of years ago I instead a Perless (Delta) kitchen faucet in my house.Years later the hot water dropped to a trickle.Took the ball out and the seals on springs on under then on the hot side was piece of rubber.I grabbed it with needle nose pliers and worked and worked finally got it pulled through.It was an 1" or so long tube with a flange on one end and the other end closed, but with a slit in it.Could not figure out where it came from or how it could have gotten through the 3/8" tubing that are on the faucet stub outs.Called customer support and they had not ideas what it was or where it came from.But the thing worked fine after I got it pulled out.Several years later I was going through the kitchen drawer that had all of the manuals for all of the appliacnes and found the instructions for that faucet.Those where check valves that went in the end of the tubes and the flange was part of the seal to the supply lines. Appartenly I cranked them down hard enough that pusht the flange out and into the tube.But the connection never leaked..
William the Geezer, the sequel to Billy the Kid - Shoe
I just put a compression ball valve in my basement a couple weeks ago. did the same thing. Very slow drip for a couple of hours, then dry. I've had this happen before, so far I haven't seen a leak reappear once it stops.
i have found compression fittings especially on old copper like to leak so i sand the copper same as for soldering and have had no problem since
I think shutoff valves are a joke. by the time you need them they don't work and need to be replaced. Then you have to shutoff the water to the whole house anyway.
I've been installing the 1/4 turn shutoffs for years now but haven't had to use one yet. I hope the ball valve in them lasts longer.
OB
Waiting for the 17 and 20 year olds to wake up and open some gifts.
My guess when I've seen it close up has always been that either the metal is slightly deforming, especially on the hot side, or more likely all the minerals and other #### in the lines plugs up the pin holes. Straight up guess there though.
I replaced my dishwasher a few weeks ago
I had installed the old dishwasher five years ago and used a braided stainless steel water supply line
I decided to save $10 and not replace the water line
I installed the dishwasher and when I tightened the old water line on the new dishwasher it didn't feel right
I turned on the water and it was dripping
After messing with it for a couple of days, I got a new stainless steel water supply line and installed it and wala no more leaks.
The built in rubber washer had hardened quite a bit in five years and resulted in the leak.
That's my story
I just replaced 2 basin faucets in a 40 YO house. I think that most if not all was orginal.None of the 4 shutoff valves would turn.So I replaced then all. They where compression fit.With all 4 of them I could pull the old ferrules right off. And there was no sign of any leakage around them over the years.So, unlike my usual practice, I replaced them all with new nuts and ferrules. And none of them leaked even the slightest amount of moisture. Usually I would expect at least one to weep a drop before I tightened up just a bit more.And I had to replace on of them because their was a wrong size shutoff in the box. And that did not weep either..
William the Geezer, the sequel to Billy the Kid - Shoe
Heck, I lay awake at night worrying about compression fittings I installed ten years ago -- the things are that untrustworthy. But usually once the fittings are sealed tight they don't begin to leak, so long as they're not disturbed.
(There are a couple of tricks to getting a good compression connection: First, don't push the pipe tightly into the fitting, but leave about 1/32" expansion room at the end of the pipe, before it bottoms out in the fitting. Second, apply a tiny dab of some sort of lube to the ferrule before installing.)
Undersink, where appearance isn't a problem, I avoid using brass/copper risers (and their compression fittings) and use the braided steel hoses instead. They're much less of a hassle.
BTW, after installing any compression fittings, always go back 2-3 days later and check for leaks.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
I dont know if someone already said this, but push the pipe all the way into the fitting and then back it out maybe 1/8" When you tighten it all up, the pipe buried in the fitting while tightening the fitting is a push-me-pull-you scenario and makes for potential problems. (I learned that the hard way) and also use pipe dope.
I had same issues till I applied the above 2 things and then no more.
Re. dripping stopping, my guess is debris in the pipe or hard water just filled the small leak.