Advice wanted on dealing with leaking compression fitting

[Sluggo]

I'm a pretty experienced DIY plumber. Six months ago I installed 1/2" copper piping for a new powder room, with a pair of standard shutoff valves under the sink. After a couple of weeks I noticed a very slow leak from the compression fitting nut on one of the valves, so I cranked it down another quarter turn with a pair of wrenches and that seemed to stop it. It's been fine for months, but last week I just happened to look under the sink and found the same valve leaking again, but even more slightly (only about one drop an hour). However, I had to really crank down to stop the leak originally and am not sure I want to try to tighten it any more (and possibly distort the copper tubing). So, I'm thinking of removing the valve, using a compression ring puller to get the old ring off, and then installing a new valve. However, the working space is really tight because the leaking valve is about an inch away from the side of the cabinet under the sink, so I want to do the easiest thing that fixes this for once and for all.

I see three options:
1) Leave the old valve in place and try to tighten the nut some more (can you screw up the copper tubing by over tightening or make it impossible to get the old ring off?)
2) Take the old valve off, leave the existing compression ring in place, and just install the new valve
3) Do a complete install of a new valve as described above

I'd like to hear opinions on how you would approach this. Thanks.

 

[hj]

1. YES to both questions
2. THe ring is probably the problem
3. your best bet.

 

[Sponsor]

 

[Sluggo]

1. YES to both questions
2. THe ring is probably the problem
3. your best bet.

hj-
Thanks, I sort of thought that option 3 would be best, but it's always good to get a confirmation from you that I'm going in the right direction.

 

[Dj2]

After you successfully remove the old valve, the old sleeve and the old compression nut, INSPECT the nipple. If out of shape, you may want to repair it, if needed and use a different type of angle stop and not another compression type.

 

[Sluggo]

dj2-
Thanks for your thoughts, too.

 

[BazMan25]

I agree with hj. I would probably just get a new ferrule, throw it on, and see if that works. If that fails, whole new compression fitting.

 

[PlumbSolve]

Couldn't you just try put some glazing putty into the nut. When you tighten it it squeezes through all the gaps and it never hardens. In my country this is standard practice. If we can move the fitting another option is to wind some ptfe on the ferrule and re tighten.

 

[Terry]

Couldn't you just try put some glazing putty into the nut. When you tighten it it squeezes through all the gaps and it never hardens. In my country this is standard practice. If we can move the fitting another option is to wind some ptfe on the ferrule and re tighten.

I have sometimes used a bit of pipe dope on ferrule and threads. Rarely though. I don't use tape on compression. Most of the time I'm stripping that stuff off to fix a leak.

I like to remove the backing nut and ferrule and start over with a new shutoff.

 

[PlumbSolve]

Sorry what is pipe dope.?We find recently alot of companies are making compression fittings. They are much lighter in weight and you can hear them schreeching sometimes when you tighten them. A well made compression fitting will have a bigger angle on the fitting and a slightly smaller angle on the nut.the idea here is that when it is torqued the pipe will have more surface area in the fitting and not on the nut. This prevents the pipe from turning as you tighten it.The give away of a poorly made fitting is when the pipe starts turning in the fitting while you are trying to tighten it up. I find a bit of tape on the ferrule sorts out alot of difficult fittings but I prefer using putty. (The manufacturers recommend nothing But habits die hard.) I never bother to use tape on the threads as its not doing any work except to tighten the fitting.

 

[Reach4]

Sorry what is pipe dope.?

Pipe compound/sealant, such as Rectorseal #5. It both lubricates plus fills small gaps.

If using putty on plumbing here, we would use plumber's putty rather than glazing putty (glazing compound). Glazing compound sets harder I think. There was probably a time where the same putty was used for both jobs.

I used Rectorseal #5 on a compression fitting that had leaked, but I also used a lot more force in tightening. It worked, but the greater torque was probably the more important part. I had been afraid of crushing the tubing the first time.

 

[Terry]

Maybe some oil on the threads, but normally I tighten without adding any. It's just for lubrication of the threads. The seal isn't there anyway.

 

[Dj2]

I wondered if you solved your situation.