Compression Joints - how tight and which type of olive?

[compheat]

All compression fittings should be hand tight then one and a half turns.
So mark the fitting then one complete turn and then half turn and thats that.

Thats the correct method has stated by Pegler and Conex.

The use of PTFE is something that as come about due to all the S###e fittings that are on the market.
Ive had olive's that won't even tighten etc.

 

[SaladFingers]

I know it's an old thread, but have been doing some searching and thought I'd post my thoughts on what some have said...

...where some say that PTFE is a 'bodge' or for 'diyers' only, I disagree, as where there are parallel fittings such as potable water expansion vessels, PTFE being wras approved is a good method of getting a seal on course threaded male to threaded female joints. Boss white or hawkwhite isn't wras approved for use on potable water systems, so I only use that on heating water or gas. Jet blue is wras approved, but not suitable for threaded joints alone, it's really only a suppliment to ptfe, hemp or olives.

 

[Axel]

You miss the point. Of course PTFE can be used on THREADED joints; that's what it's for. But it's not meant for use on compression joints, not on the olive or the backnut thread. That is a bodge. PTFE on an olive can lead to a joint that is tight enough to make a seal but not tight enough to grip the pipe presenting a risk of the fitting catastrophically blowing off the pipe.

 

[petit_pablo]

Impressive - dragging up a 2 year old thread to then completely miss the point of it

 

[SaladFingers]

Impressive - dragging up a 2 year old thread to then completely miss the point of it

I think it's you that has missed the point. I'm replying, as I said, to the comments of the general use of PTFE and again, as I already said, I know it's an old thread - I were doing a search and thought I'd leave a comment.

 

[petit_pablo]

The thread wasnt about the general use of PTFE though its asking about PTFE on compression fittings.

 

[SaladFingers]

The thread wasnt about the general use of PTFE though its asking about PTFE on compression fittings.

I know and again, as I've already said, it was in reply to people saying that PTFE is for bodgers or diyers - those who said that didn't say 'oh but apart from parallel threaded joints.

 

[Axel]

When it was said, in this thread, that PTFE was for bodgers, they were specifically referring to its use in compression fittings, not its other uses.

 

[Axel]

Better slightly overtight than undertight, IMO.

http://en.wikipedia.org/wiki/Bodging

 

[Axel]

"They" say that if you can look down the inside of the tube and see any slight indentation from the tightened olive, then it is overtightened. I would argue that a slight indentation is better than the risk that the fitting is not tight enough and may leak of blow off under pressure. The design is quite clever in that if an olive to pipe grip is tight enough to not leak it means that it is physically tight enough, but this effect is negated if PTFE is used.

 

[Terrywookfit]

"They" say that if you can look down the inside of the tube and see any slight indentation from the tightened olive, then it is overtightened. I would argue that a slight indentation is better than the risk that the fitting is not tight enough and may leak of blow off under pressure. The design is quite clever in that if an olive to pipe grip is tight enough to not leak it means that it is physically tight enough, but this effect is negated if PTFE is used.

The ptfe is not between the olive and pipe so it will not affect its grip on the pipe.

 

[Terry lambert]

I wonder if any of you have gone to change a rad valve and someone has murdered the pipe previously, then wrapped a bit of ptfe around the olive and nipped it back up.

I've seen this more times than I can count, and by professionals

 

[Axel]

"They" say that if you can look down the inside of the tube and see any slight indentation from the tightened olive, then it is overtightened. I would argue that a slight indentation is better than the risk that the fitting is not tight enough and may leak of blow off under pressure. The design is quite clever in that if an olive to pipe grip is tight enough to not leak it means that it is physically tight enough, but this effect is negated if PTFE is used.

The ptfe is not between the olive and pipe so it will not affect its grip on the pipe.

No but it is assisting the seal so the cowboy wot tightens it may not tighten it as much as they should - I have come across a few where I can undo the nut with my hand and slide the olive off freely.

 

[Axel]

I wonder if any of you have gone to change a rad valve and someone has murdered the pipe previously, then wrapped a bit of ptfe around the olive and nipped it back up.

I've seen this more times than I can count, and by professionals

Fair dinkum, in times of trouble.....I prefer to renew the pipe end ideally, even sometimes I tell the client that if they don't want the whole heating circuit drained they can have a push fit on the radiator pipe at skirting board level.....

 

[Terry lambert]

My point is, used by a professional, correctly, there isn't a problem, anything used by a novice can lead to heartache, that's the risk of DIY.