3/4" olives that don't seal....

[GRC]

I needed to put in a 15mm branch from 3/4" pipe, and conventional wisdom is that a 22mm fitting with a 3/4" olive would provide a satisfactory seal.

Having laid out all the requisite pieces (22/22/15 tee from B&Q; 3/4" olives also from B&Q, tools etc), I noted that the olives from the tee and the 3/4" substitutes had a different profile; the 22mm ones with the fitting had an outer oval profile, the 3/4 had a flat-topped profile.

Double checked that the 3/4 olives were a snugger fit on the pipe than the 22mm, and assembled and tightened. Turned the water on, and got weeping from both 22mm ends, but watertight on the 15mm branch. Tightened up a bit more, with no more success. Tightened as much as I dared (holding the fitting body steady), using a 12in wrench, and on close inspection there was still a slight weep, apparently from the inside of the olive (the edge of which was visible through the fitting nut).

Tried some PTFE tape over the fitting thread and olive, with same result.

Decided to try fresh fitting and olives, opened a second pack, taking scrupulous care (as I did the first time) to keep them clean, and not get any muck on the surfaces. Took out a little more pipe, and in went another 22/22/15 fitting (in case the first one was faulty), a short section of 22mm pipe, and a 22mm straight coupler. 3/4 olives on the outer joints, 22mm olives on the inside ones between the 22/22/15 and the straight coupler. Result? Slight weep from the 3/4 joints, sound joints with no problems on the 22mm.

Possible conclusions;

The flat-profile 3/4 olives aren't compatible with the fitting, which originally had rounded profile 22mm olives?

The pipe isn't quite 3/4 inches?

I just didn't tighten them enough? (but the 22mm were tightened to the same degree and were sound, though.......)

I'd welcome any other suggestions or tales of similar experiences....

Oh, and forgot to mention - I'm going to try setting up a test rig in the workshop as soon as I get a chance, see if I can pin down a definite cause; all suggestions gratefully received in the meantime.....

Regards, Graham
__________________________________
Moderator please note 10a

 

[ArtfulBodger]

Never had any problems with imperial to metric myself, but you could always try wacking a load of sealing compound on the joint before assembling. The PTFE on the threads won't achieve anything btw. You're sure you're not overtightening them are you?

 

[corgiman]

22m Diameter is NOT 3/4 mate

you can get away with it with 15mm but not 22mm you gonna need some imperial olives.

failing that you MAY get away with copper 22mm olives

sorry

 

[Porker]

corgiman - having read the original post it appears that GRC knows about this difference but is still having problems. Have to say in my experience 3/4" olives with a 22mm fitting have worked well (after finding out the hard way). I have also noticed the difference in profiles of the olives and wondered whether the fittings need to be matched but again have mixed and matched without any problems.
I have just fixed a leak in my bathroom (behind tiles) where the fitting threads had cracked a hairline through the fitting wall. As you have replace the fitting itself it would appear not to be this.

Have just been recommended Fernox LS-X for sealing which may help you. I have used it on threaded joints.

 

[PEDANTICVINDICTIVEMAN]

Test rig in the shed, sad very sad, put some jointing paste on EVERYTHING and tighten the bloody thing till it screams in agony, they never leak when I do it, test rig jeez wish I had the time to fanny around.

 

[GRC]

Test rig in the shed, sad very sad, put some jointing paste on EVERYTHING and tighten the blooddy thing till it screams in agony, they never leak when I do it, test rig jeez wish I had the time to fannyy around.

GRC - Wot, no hobbies? Making model shower cabinets from matchsticks, boiler replicas from cardboard, that sorta thing? No?

Regards, Graham

 

[shaggy]

No need to overtighten them, a smear of silicone is ok on the olive.

 

[trooper]

Q..... when u the first lot leaked were u able to slide the olives off the pipe,
is so then scrap the happy shopper olives and get some from a merchants!!
If not joint ing compound all round the olive has gotta do the trick.

 

[GRC]

Q..... when u the first lot leaked were u able to slide the olives off the pipe,
is so then scrap the happy shopper olives and get some from a merchants!!
If not joint ing compound all round the olive has gotta do the trick.

GRC - Nope. They were on there solid. If I could've got them off I would've tried the second fitting and olives with the pipe as was, rather than cutting more away and putting the 22mm pipe and straight coupler in.....

Jointing compound - on the inside and outside of the olive?

Regards, Graham

 

[GRC]

No need to overtighten them, a smear of silicone is ok on the olive.

GRC - Standard kitchen/bathroom silicone sealant, as used on tiling/bath/basin joints? Both inside and outside of the olive?

Regards, Graham

 

[doitall]

fernox LS-X is much better

 

[kevplumb]

Test rig in the shed, sad very sad, put some jointing paste on EVERYTHING and tighten the b****y thing till it screams in agony, they never leak when I do it, test rig jeez wish I had the time to **** around.

old man always said hit it till it screams for mercy

mind he was a brickie

 

[ChrisR]

Were the 3/4 olives copper? They don't stand overtightening. I hates them.

 

[shaggy]

Graham, the olive should seal on the fitting without any sealant. If you've got a problem then the leak is not between the olive and pipe, it's where the olive touches the chamfer on the fitting, so this is where a smear of silicone is needed. LSX is a fine product but it is still a silicone rubber sealant. It's expensive and has a shorter shelf-life than bathroom silicone, which is what I say is ok.

 

[GRC]

Were the 3/4 olives copper? They don't stand overtightening. I hates them.

GRC - Yup.

Regards, Graham