Compression fittings - simple question


Postby prbaxter » Wed Jan 16, 2008 11:08 am

Could anyone please clarify what should be used to seal a compression fitting - if anything.

Should I PTFE the thread at all?
Should I silicone grease the thread?

Or should I leave it as it is and let the olive do the work?

How tight should they be? Is it possible to overtighten and dig the olive right in to the pipework?

Just fitted a shower, didnt use anything and it seems fine.
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Postby thedoctor » Wed Jan 16, 2008 1:05 pm

See our project on copper compression fitttings. It will not hurt to use PTFE or Boss white/green paste and yes, you can overtighten. Have a practice on a fitting and a piece of pipe first, it will save you worry in the long run.
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Postby prbaxter » Wed Jan 16, 2008 1:14 pm

thanks thats most helpful.

Might it be worth adding a note on there about wrapping PTFE in the direction of the thread (otherwise it comes off when you screw it in)?

Thanks again, tape and paste it will be as i'm plumbing in the wall.
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Postby simpleton » Wed Jan 16, 2008 3:54 pm

i always use ptfe. you shouldnt put anything on the thread cos your just making it difficult to tighten. 4 or 5 wraps halfway around the olive and the pipe so that it fits snuggly into the fitting as this is where leaks can spring from. thats my pennys worth
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Postby htg engineer » Wed Jan 16, 2008 4:46 pm

If you're using new pipe and new fittings you don't need any jointing compound or PTFE tape.

If you're pipes are going to be sunk into the wall it would be best to use soldered fittings - or preferably and if possible - no fittings at all.
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Postby marrtin » Wed Jan 16, 2008 10:42 pm

Tighten until the olive just grips the pipe, then tighten again about 1/3 to 2/3 turn. Test for leaks before covering. No need to use ptfe or joint compound.
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Postby frogger » Wed Jan 16, 2008 10:48 pm

It is best pratice to not make dry fittings. Use boss white you can not go wrong.
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Postby rosebery » Thu Jan 17, 2008 12:24 am

"4 or 5 wraps halfway around the olive"

I would say that you are then relying on the PTFE to provide the seal rather than letting the olive do it's job.

Cheers
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Postby rosebery » Thu Jan 17, 2008 12:29 am

"If you're using new pipe and new fittings you don't need any jointing compound or PTFE tape.

If you're pipes are going to be sunk into the wall it would be best to use soldered fittings - or preferably and if possible - no fittings at all."

Yup and also if the pipe is in the wall then wrap it well before plastering. Otherwise there is the possibility of corrosion in the future. Insulating the pipe also allows for thermal expansion.

Cheers
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Postby marrtin » Thu Jan 17, 2008 10:23 pm

There you are prbaxter. Clear as mud eh? Lol

Now i'm confused.
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Postby prbaxter » Fri Mar 14, 2008 10:47 pm

yes - all very confusing now.

the piping will be inside a stud wall, so plaster contact will not be a problem.
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Postby dcc » Fri Mar 14, 2008 11:07 pm

also, dont use PTFE tape and paste together. they react with each other which will [b]eventually[/b] cause a leak.
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Postby prbaxter » Sat Mar 15, 2008 10:09 am

would it not just be easier to use plastic pipe and pushfit fittings?
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Postby MB » Sat Mar 15, 2008 2:30 pm

Might be worth bearing in mind that you shouldn't use boss white on a cold feed. You should use boss green if its on a cold feed.
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