Stop Valve Compression "confusion"

I know I'm making this "MUCH" harder than it is but I again don't understand how much pressure to apply when tightening this fitting. I tested with a piece if 1/2" copper...put the nut on, then ferrule, bottomed the valve out, slid the ferrule close to the valve, then hand tightened the nut, then took a wrench and maybe turned it half turn with a lot of pressure. I even tried to pull valve off pipe - couldn't (I have a fear of water pressure blowing it off) then I unscrewed nut to remove valve and the ferrule slide right off...didn't even looked scratched? I'm baffled!!

If it doesn't turn and doesn't leak, it should be fine.

Do the real connection as you described doing the test, but this time put a few drops of light oil, 3 in 1, sewing machine, or similar on the threads. Don't use pipe dope or tape. If it leaks, tighten it some more.

Gary Swart said:

Do the real connection as you described doing the test, but this time put a few drops of light oil, 3 in 1, sewing machine, or similar on the threads. Don't use pipe dope or tape. If it leaks, tighten it some more.

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You're recommending to put a petroleum product in the potable water supply? WTF? Use pipe dope or tef tape. The compression fitting depends on deforming to make the seal. You should not need to slip the compression ring off. What size wrenches were you using? The amount of torque applied is relative to the person. What seemed like a lot to you might not be enough. Try upsizing your wrenches. You won't hurt the pipe.

I use a dab of plumbers grease when I install compression fittings.

Thanks for the comments. I'm sure it's all about the torque as I will soon find out. I'll nix the tef. tape/pipe dope/ etc. and do this dry but apply more torque.

Thanks again...

You're missing the point! Use Grease! It allows the threads to be lubricated so you get the right torque!

Plumbers grease will certainly be OK. But, yes a few drops of light oil will can also help. Light oil is not poison and the minute amount you would actually get in the water supply would be so diluted by the time it got to a faucet, you would never taste it. Remember, it goes on the threads not inside the pipe.

I agree with Gary and Redwood - this is all about lubing the threads with something that won't get in the way of the nut adequately deforming the ferrule. Teflon tape, and even some thick pipe dopes, can interfere with the nut tightening enough to do the job.

Terry posted info from one of the compression stop manufacturers to use a couple drops of oil on the threads some time ago.

If it makes you feel better, use castor oil ...

Gary Swart said:

Plumbers grease will certainly be OK. But, yes a few drops of light oil will can also help. Light oil is not poison and the minute amount you would actually get in the water supply would be so diluted by the time it got to a faucet, you would never taste it. Remember, it goes on the threads not inside the pipe.

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I just wouldn't want to take that chance.

Mikey said:

If it makes you feel better, use castor oil ...

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It would make me feel better, thanks.

Oil is toxic, caster oil will rot over time. Use plumber's lube, the stuff you put on shower valves to make them work smoothly. It is non-toxic for many years.

lube

If the manufacturers want lube on the compression threads let them put it on when they assemble it.

What about using Dow 111 silicone lube on the threads. One tube lasts a lifetime?
http://www.bigbrandwater.com/dow111.html

I use this for o-ring lube on water filter o-rings.

Jerry

At the rate I'm going, it looks like it will last for several lifetimes. Good stuff.

gear junkie said:

It would make me feel better, thanks.

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I have a hot flash for you. That VALVE...even though it complies with Federal ULTRA LOW LEAD standards, if sold in California, will come with a prop 65 WARNING: CONTAINS PRODUCTS KNOWN TO CAUSE CANCER OR REPRODUCTIVE HARM.


As far as the torque, if you could easily side the ferrule off after, I say you were close but not there. I think if you pulled hard, you might have removed the valve.

I tighten 1/2 or so with about a 10" crescent. When it gets to the point that I can feel it is snug...valve does not turn FREELY...then I go another 1/2 to 3/4 turn. At this point, you should be able to grasp the valve FIRMLY and not turn it.

You do NOT tighten it to a formula, such as "hand tight and a half turn additional". You tighten it until it does not appear that you can turn it any further.

My 2 cents is not about the copper pipe/ stop valve compression fitting (I do believe, as HJ said that you don't have to be too delicate when you tighten this nut) but at the other end... flexible stainless steel supply hose to faucet connection. I think I read on this forum where this nut should not be tightened to much otherwise the rubber gasket could get mangled and ruin the integrity of the seal. Well, a few months ago I installed a new lavatory faucet along with a new 1/4 turn stop valve and new supply hose. I tightened the subject nut, hand tight and about 3/4 turn more with a 10" wrench. Turned on the water and viola, no leaks. Monitored it for a couple of days and I thought I was home free. The night after I last looked at it, the hot water connection started leaking and in the morning when I went to use the bathroom, a plastic tub (holds about 2 gals.) under the stop valves/faucet connections (this is my fail-safe strategy) had overflowed and dumped another couple of quarts of water onto the cabinet base and on the bathroom floor!! I was P.O. to say the least! My critique is that when I used the hot water that night to the extent that it heated up this connection, there was some realignment/shifting in the mating and it started to leak. In my initial test, I neglected to run the hot water long enough (it takes a couple of minutes for the hot water to reach this faucet) to heat up the connection and so it was not a really good test! Live and learn... Oh yeah, I tightened the nut about 1 and 1/2 turns more and so far so good. Plumbing for the diy'er is tough!!