collapsed compression joints

[Guy King]

The message from "Doctor Drivel" contains these words:

Can't see why it matters whether the threads are sealed or not. They're nothing to do with the hermeticity of the union.

[Chris Bacon]

I don't know why Drivel is recommending using tape *at all*. I would not.

[Doctor Drivel]

Exactly.

[Doctor Drivel]

I didn't. Read the post.

[Dave Plowman (News)]

Pulleeze. I don't shout on newsgroups.

Tightening them 'till they groan' - and any mechanic will know what I mean with clean dry brass - has always worked for me. As has a few turns of PTFE tape round the olive. Others say this causes a leak. Some manage to pull out pipes. Mine are all fine.

If the makers want to be really helpful they should give a torque setting for the various sizes. Finger tight and so many turns is only really applicable to stretch bolts etc used on car cylinder heads etc if some accuracy is needed.

[Dave Plowman (News)]

Yup.

Works for me.

[Doctor Drivel]

It is very different to sealing compound.

[George Tingsley]

Look Drivel I will type this very very slowly since you have pro reading difficulties I have repeatedly said that you should not use ptfe on the Olive of a compression fitting as your mate DP has suggested I even included this web page with pictures to show

you should not and why you should not over tighten and that it is the olive alone that forms the water-gas seal

I have never on this subject said or implied that the use of ptfe on the threads of a compression fitting would make a better seal or stop a leak The manufactures are not claming that this helps make a better seal its Recommended use on compression fitting threads is for its thread lubricating and anti-seize properties at least your mate plowman seems to understand the simple principle of brass to brass contact but then wraps the olive in ptfe instead of the threads

[George Tingsley]

I don't think so given the full quote Use proper open ended spanners and tighten them till they groan. You won't over tighten them unless using something silly like large Stilson.

do you accept that over-tightening compression fittings should be avoided do you accept the general recommendation that from finger tight it is somewhere between 2/3 and 1-1/4 turns to make an effective seal do you do any plumbing if so try an experiment wrap the -olive- but not the threads in ptfe tape as DP would now tighten fitting till it groans or squeaks how many turns did this take and what condition was the pipe and olive in afterwards

[Doctor Drivel]

Idiotic bodger, read what I wrote,. Read it 5 times. Whatever you don't understand get back to me.

The senile one is not my mate, and debating with a such an obvious senile person is futile.

We all know you don't overtighten compression fitting, the senile one doesn't.

You put silicon grease on the threads not PTFE for anti-seize.

[Chris Bacon]

Yes - you're preaching to the converted. I have never used PTFE, bath caulk, "instant gasket", Hermetite red or golden or blue or anything else on compression joints.

Sometimes...

it won't work since the tape will lubricate the joint

(theoretically) lots

(theoretically) both shagged.

[Dave Plowman (News)]

FFS. Get a life.

Which gives a vastly different number of turns after finger tight for a

1/2 inch fitting than you recommended in a post.

Make up your mind. Either Calor is correct or not.

[Dave Plowman (News)]

Then you think wrong. It's *exactly* what I meant.

And I stand by that too. The correct open ended spanners are of a length that will prevent overtightening.

Somewhere between? Very exact that. And could represent more than a doubling of the pressure on the seals.

Err, how are you going to know what condition they should be in? The acid test is if they leak or pull apart. Nothing else really matters.

[Dave Plowman (News)]

No - it's the threads that groan as well.

[Chris Bacon]

So everyone should stop moaning at Drivel? The think is, G.T. is right, and knows it.

[Chris Bacon]

You can't rely on this technique at all, though.

Individuals can apply more or less turning force on the fitting with the same spanner, so that does not work either!

[Chris Bacon]

*BUT THE ATTRIBUTIONS WERE MUNGED YET AGAIN*

Anyone relying on making consistently good compression joints by "tightening them till they groan" is doomed to failure.

Making a compression joint is not the same as doing up an exhaust manifold.

[Dave Plowman (News)]

I can and do. What you do is up to you.

As they can with anything. It just requires a 'feel' for such things. And the day I get a leaking compression fitting I'll worry about my technique.

[Dave Plowman (News)]

Strangely I'm not. Not had a failure I can remember. Perhaps it's down to the PTFE round the olive? ;-)

I use a torque wrench were necessary. But would happily tighten such things as manifold nuts without. It's called experience, I'd guess.

[George Tingsley]

.

Thank you Drivel case proven I think