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SteveDel 07-27-2009 05:01 PM

Small leak in compression fitting
Hey everyone. My plumbing under my kitchen sink was super corroded and figured I'd sleep better at night knowing it was fixed so I set out to do my first plumbing job since I bought my house.
I just finished replacing everything under the sink and it looks great. My only concern is one of the compression fittings that connects the copper piping coming from the faucet to the flexible faucet hose is leaking. It's not a big leak (I have to wait a minute or so for a drop to appear). I've tightened up the fitting quite a bit to get it to this point and am worried that I might bust something if I try to tighten it up any more.
Is it worth trying to get another 1/4 turn on it or will a leak like this stop leaking after a bit??
Thanks for your help!

kok328 07-27-2009 05:39 PM

With compression fittings, there is such a thing as "too tight". When this occurs, replacement is the only option. You'll have to cut back the portion of pipe where the compression ring (ferrel) bit into the pipe. Of course this may leave the pipe too short and replacement of the entire length is now in order. However, it won't hurt anything to give a bit more tight to see if this will stop the leak, just make sure you don't break the connection while attempting this.

SteveDel 07-27-2009 05:45 PM

Sounds like a plan. I made sure to leave a little extra length of pipe just in case I messed things up so I'll tighten it up and see how things go.

Nestor_Kelebay 07-27-2009 06:33 PM


Originally Posted by SteveDel (Post 32685)
so I'll tighten it up and see how things go.


Trust me when I say this as I have absolutely no reason to lie:
Before you do any more plumbing, learn to solder.

Buy yourself a length of 1/2 inch copper pipe, some cheap fittings, a GOOD quality torch that mixes the fuel with air in a short tube before igniting the mixture, and some lead free solder. Follow the basic directions in any DIY Plumbing book, and by the time you end up going through those $100 of materials, you'll be proficient at soldering.

I say that because a soldered joint is the only plumbing connection I would trust inside a wall where I can't see that connection to know if it's the source of a leak. That's cuz it's an extremely rare thing to have a soldered joint leak if it didn't leak the first time it saw any water pressure.

You're already starting to do your own plumbing, and the more compression fittings you install, the more you'll regret not having learned to solder first. That's because you'll be wanting to go back and redo all that plumbing with soldered joints.

Most newbies are kinda scared of soldering, so it's an important milepost to achieve, and it's better to do that before you have all kinds of compression fittings in your house that you'll subsequently wish were all soldered joints.

SteveDel 07-27-2009 07:01 PM

Nestor that sounds like great advice. I've read enough to know that you never put a compression joint inside a wall. I planned on getting a length of copper pipe and soldering away till I was confident enough to do it for real but there were a few issues. The pipe coming out of the wall is very short. I had to take off the old fittings with a torch since there wasn't enough room to cut the pipe. I figured that soldering this joint would be pretty difficult for a noob. Another thing that kinda frustrated me was the lack of selection for copper fittings at Lowes. I probably need to find a local plumbing supply store.

I will take your advice and buy myself a length of pipe and some fittings and get comfortable with soldering. Hopefully I'll be able to replacing my work under the sink in the near future with a more permanent solution.

Thanks again!

Nestor_Kelebay 07-27-2009 10:58 PM


Originally Posted by SteveDel (Post 32691)
Hopefully I'll be able to replacing my work under the sink in the near future with a more permanent solution.

Gawd I hate to tell you this, but that's the kick in the A$$ with compression fittings. When you tighten a compression fitting onto a copper pipe, you actually crimp a brass sleeve (called a "ferrule") onto that pipe with a compression nut behind that brass sleeve. So, I kinda doubt you're gonna be able to get that brass ferrule off without cutting it off. Like, I mean, cutting the pipe behind the ferrule to remove that ferrule so you can solder a coupling onto that pipe and extend it a bit further. Do you even have room to do that?

Does anyone in here know if it's possible to cut a brass compression fitting ferrule along it's length and then pry it off the copper pipe? What tool would a person use to cut the ferrule without mucking up the pipe?

I have heard people say that you can remove a brass ferrule from a copper pipe, but how it's done, I have no clue. The force with which you've crimped that brass ferrule onto that short piece of pipe may make removing it a pipe dream.

If push comes to shove to fix that leak, undo that compression fitting, wrap some soft teflon tape around that ferrule as best you can to make a water tight seal between the ferrule and the fitting and put the compression fitting back on, but don't tighten the bygeezus out of it. Just a bit more than snug should be OK.

Watch this Plumbing forum for a post on basic instructions on how to solder. I will also explain why each step is done. If you know what you're doing and why, you'll have much more confidence doing it.

Does anyone else have any idea of what to do here if Steve can't stop that leak without busting something?

inspectorD 07-28-2009 06:08 AM

You really need to cut the pipe at the fitting. I have never been able to get one to work properly after it leaks, and I have replaced many kitchens.
Your other option is to buy a longer flexible line and another fitting if you are short on distance. Just make sure you have access to where the fitting connects.
I had this issue with my own dishwasher. I just gave up on the copper line with compression fittings and switched to a braided stainless steel flex worries.:D

Absolutely learn how to sweat pipe...todays tools have made it easier, just be careful where you point the flame.

majakdragon 07-28-2009 11:52 AM

Most compression fittings leak due to the pipe not being pushed all the way into the fitting. This prevents the ferrule from properly seating. Old Plumbers trick for some compression fitting leaks is to run a piece of heavy string through a candle a few times. Then cut off enough to wrap around the pipe once or twice, above the ferrule, than reconnect the nut and tighten.

travelover 07-28-2009 06:10 PM


Originally Posted by inspectorD (Post 32703)
...<snip>.....I had this issue with my own dishwasher. I just gave up on the copper line with compression fittings and switched to a braided stainless steel flex worries.:D......<snip>....

Me, too and I've never figured out exactly where I was going wrong with the compression fittings. :confused:

SteveDel 07-29-2009 05:11 PM

Well I cut off the compression fitting and put in another one, tightened it up, and it's working fine. I did have a couple of questions for the future though.

First, about the short pipe coming out of the back of my kitchen cabinet. I'm guessing if I cut out the back of the cabinet and the drywall I would find a supply pipe coming up from the floor to a 90 degree fitting to the short pipe. I could use the torch to get the short pipe off of the 90 and solder in a new longer pipe, correct?

Second, my original problem was with connecting the braided flexible pipe coming from the shutoff valve to the 3/8" copper pipe going to the faucet. I had to use a 3/8" compression to 1/2" threaded connector. If I was going to go the soldering route in the future, how would things change? I guess I'm wondering what my other options would be going from the shutoff to the 3/8" pipe at the faucet?

Thank you all once again for the help.

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