Compression fittings

Don Metzinger · Jan 7, 2007

I recently had to re-use the old ferrules when installing some replacement valves and had trouble getting them to re-seal, finally got them set. Is it adviseable to use eiter teflon tape and or paste over old ferrules? I have never had any problems with new ones. Does anyone use tape or paste with either new or old?? Thanks - Don

Kordts · Jan 7, 2007

Do not use anything on compression fittings, maybe a drop of oil.

Sponsor · 2022-01-29T12:20:58-0800

Don Metzinger · Jan 7, 2007

Thanks, I was told to not use anything and have followed that advise but was wondering why? - Don

Norcal1 · Jan 7, 2007

dmetz said:
Thanks, I was told to not use anything and have followed that advise but was wondering why? - Don

Same reason you shouldn't fix a leak with duct tape.

BTW: I like to use a little plumber's grease on the threads...

Randyj · Jan 8, 2007

Because once the first connection is made to the ferrule it is like a finger print....virtually every fitting is different and the odds of getting the same old one EXACTLY in the original place at the exact same angle is very low odds so you can bet on having a leak. Sometimes you can tighten extra good to stop the leak but you may damage the nut or the fitting/valve... The ferrule is a soft metal but it still is hard to get it to seal once it is deformed by the original compression.

hj · Jan 8, 2007

ferrules

Tell that to the hundreds, and thousands, of ferrules I have reused by just connecting the old nut to the new valve. Tighten them with a 15/16" open end wrench and you will not distort them and will not have to overtighten them.

Randyj · Jan 8, 2007

hj... me too...but the guy wants an explanation... maybe I should edit that post to be a little more liberal... I definitely would not take a ferrule off of a pipe and re-use it on another pipe. Maybe I got up too early this morning.... time to get out to work... I've got to re-key a whole house and run 250' of conduit underground for multiple phone lines.... might be a long day. Too bad I don't get intelligent and stick to just one occupation...but then I don't pass up a buck!

SteveW · Jan 8, 2007

dmetz said:
Thanks, I was told to not use anything and have followed that advise but was wondering why? - Don

The reason is that the seal is actually made by the ferrule mating with the spherical female part of the fixture, and NOT by the threads. Teflon tape or thick pipe dope can interfere with the ability of the nut to fully thread far enough on the male threads to adequately compress the ferrule.

Don Metzinger · Jan 8, 2007

Thanks, I appreciate all the info. - Don

SteveW · Jan 8, 2007

You're welcome! I learned that little fact, along with dozens of others, on this site - great place to check in on regularly.

Mike Swearingen · Jan 8, 2007

I'm not a pro plumber, but I've been DIYing it for more than 50 years.
Who says that you can't use anything on a used ferrule?
I've been smearing used ferrules with a small dab of caulk for years to seal them (with new and old nuts). Works like a charm. No leaks. No problems.
Mike

Compression fittings

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