Advice needed regarding compression fitting

[dave22]

I hope to finish fitting an outside bib tap soon, and would like a little advice as plumbing is not something I have any experience with at all...

All the pipework inside and out was already done as I am essentially replacing an old tap which was never much good (an ancient thing that didn't fit well onto the garden hose). The outside pipe burst near the old tap last winter (forgot to drain it...), so I have carefully cut off the bad end with a proper tube cutter, and deburred the new exposed end with steel wool.

The one thing that worries me most is fitting the tap plate to the pipe. The plate is a standard elbow connection which screws into the wall: 15mm compression end to pipe and 1/2 inch screw+PTFE end to tap.

I know I must not overtighten the nut, and that I need to use a wrench to hold the plate still (although it will be screwed to the wall) while tightening the nut. Here are my questions:

1) Is there a danger that the pipe itself will try to turn as I tighten the nut? Could this put strain on the connections inside the house?

2) Once the nut is hand tight, how much extra should I expect to have to turn it with the spanner? Different websites say different things - anything from 1/2 turn to 1&1/4 turns. Do I start with 1/2 turn, test it, then gradually tighten until it doesn't leak, but stopping and abandoning after 1&1/4 turns so as not to overtighten?

3) If it doesn't work, is it simply a matter of removing the plate, replacing the olive, and trying again? Or will the end of the pipe be too squashed after the first attempt...? (If the latter, how do I proceed without cutting off the squashed part of the pipe? This would mean drilling new holes in the wall to move the plate along )

Any tips much appreciated,
Dave

 

[dextrous]

No worries of it trying to turn the pipe and causing strain within the house.

Don't bother with wrench to hold the wallplate steady - just screw the new tap in a few turns until it's horizontal, thus enabling you to have a useful handle which doesn't get in the way of the spanner.

Tighten the nut hand tight (don't put ptfe on the olive compression part- it's not necessary), then about 1/2 turn more with the spanner. PTFE up the tap thread and hand tighten this - not too tight . Turn the ater on to see if the compression joint leaks - if it does just keep on tweaking it until it stops, that a little tweak for luck.

 

[dave22]

Thanks for the reply and reassurance. But what about (3)?

If, by bad luck, the olive gets mangled and I need to start again, can I simply remove the plate and olive, and put on a new olive? Or has the pipe had it at that stage?

(Don't mean to sound pessimistic, but being a total novice at this I'd like to know what my options would be at that stage.)

Thanks,
Dave

 

[doitall]

I always have and always will use a jointing compound on the olive, or wrap a couple of turns of ptfe around the olive, anything is better than a dry joint.

To tighten the nut, get a 6" adjustable, and when it won't go any further it's tight enough.

Forget 3 it won't happen.

 

[dave22]

Well, I put a little jointing compound (from Wickes) around the olive, and tightened up hand-tight, then nearly half a turn with the wrench, at which point it "squeaked".

Turned on the stopcock, and the joint was clearly weeping. After 4 more squeaky nudges with the wrench, the nut is now a little over 1/2 turn from hand-tight (say 190 degrees), and the weeping is very minimal, but still there - a small drop is visible every 5-10 minutes.

I am a little nervous to keep tightening, as the last two nudges made no difference to the rate of weeping. How many more nudges do you think I can get away with before the point of no return? I really don't want to have to dismantle the whole thing to replace the olive, but nor do I want to b*gg*r up the pipe/nut/plate by overtightening.

Dave

 

[dextrous]

Just a bit more - you've a way to go before it's a gonner

In spite of what the maestro doitall says ( ), there really wasn't any need for tape or compound, but not to worry, you've not done it any harm.

Yoe have to be a complete idiot to mess up the joint, which I don't think you are. If by some complete freak accident act of god, it does go awry, undo the nut and cut through the olive carefully with a hacksaw. This, answers your point 3/. I believe.

Final edit - check this out http://www.youtube.com/watch?v=-9c5LWFI_M4

 

[Tipper]

In spite of what the maestro doitall says ( ), there really wasn't any need for tape or compound, but not to worry, you've not done it any harm.

I've been making compression joints for over 35 years and I always use a smear of compound such as Boss White or the more modern equivalents. This ensures a leak proof joint without any strain on the pipe or fittings from over tightening.

PTFE on compression joint olives is a no no as far as I'm concerned but I've come across it in various houses I have owned and am amazed that professionals use it as it is designed as a replacement for 'hemp and compound' of days of yore for threaded joints which it does very well.

 

[dextrous]

In spite of what the maestro doitall says ( ), there really wasn't any need for tape or compound, but not to worry, you've not done it any harm.

I've been making compression joints for over 35 years and I always use a smear of compound such as Boss White or the more modern equivalents. This ensures a leak proof joint without any strain on the pipe or fittings from over tightening.

Slow learner eh?

 

[doitall]

And since we're trying to educate the uneducated, run the nut back, with the water turned off and put some jointing compound around the thread, and it will lubricate the thread and stop it squeaking.

And next time buy Conex fittings and not cheap european rubbish.

 

[dextrous]

And since we're trying to educate the uneducated, run the nut back, with the water turned off and put some jointing compound around the thread, and it will lubricate the thread and stop it squeaking.

And next time buy Conex fittings and not cheap european rubbish.

Thank you, oh font of all wisdom

 

[dave22]

Thanks for all your advice so far.

After 3 more small creaks, the weeping has virtually stopped. After one hour or so, although I can't see any droplet with the naked eye, the smallest amount of moisture can be detected with a piece of tissue paper where the nut meets the pipe. I don't think it's residual moisture from earlier, as I've removed the moisture a couple of times already, waiting another hour each time.

I'm going to leave it overnight and check again in the morning.

Looking at other compression joints already in my house, I notice that about half of them have like a turquoise fur around the nut where it meets the pipe. Is this the result of ever-so-slight weeping which evaporates, leaving behind some residue over many months?

Dave