Fuel tank / pipe compression fitting

[Adrian Saunders]

Has anyone experienced difficulty in getting the olive to grip properly onto copper tubing? I’ve tried two types of olive and neither are secure. When the pipe is removed, the olive will move slightly when twisted by fingers. Don’t get me wrong, it wouldn’t pull off but, it just doesn’t feel right. 

[Adrian Cooper]

Hello Adrian,

Forgive me if this is a silly question but are you using 1/4 inch tubing and compression fitting not 6mm? The fitting in the tank will be expecting an imperial olive and pipe which is just a tiny bit bigger than 6mm and so may not grip properly on the smaller bore.

I redid all my fuel line recently and didn't have any problems with the actual fitting of the unions once I had found the correct parts online (which was a mission in itself)

I did use ptfe tape on all the threads and olives just to be sure of a really good joint.

Adrian

[Adrian Saunders]

Hi Adrian, no, 5/16” (not 8 mm) tank outlet size. Compression fittings only require the metal parts and never ptfe tape to seal. Please don’t use ptfe tape on compression fittings, it shouldn’t be used. They are designed to be used as is. Strip down and remove the ptfe tape, if it leaks without, there’s something wrong. Correct ASAP. 

[Adrian Cooper]

Hi Adrian,

Thank you for your concern. I did a lot of research on this very question and there are many who share your opinion on using ptfe tape on compression fittings. However, there are just as many who advise its use and I chose to go with that camp as their opinions seemed to be based more on first hand, practical experience. 

I hope you manage to solve your problem.

Adrian

[Guest]

Ideally you should use Swan Seal Jointing Compound which is specifically formulated for dealing with liquids on compression joints.

It is a PTFE paste for joint compounds and is recommended for 99% of liquids including petrol, jet fuel, diesel and ethylene glycol.

You only need a dab from the tin so it will last several generations of Triumph owners before requiring a replacement. All decent plumbers merchants stock it.

Regards.

Richard.

[PeteH]

Hi

I`m in the "do not use" camp. As an apprentice we where taught that a properly made Joint without any sealing compound will not leak. (and we got a right "roasting" if caught!). If it does, something is not correct, Either the Nut thread is binding, not allowing it to pull up fully or the wrong pipe/nipple/olive combination. "cross threading" especially on fine threads can also be an issue. I can still make a gas-tight joint from scratch!. Another fail point can be the face of the Female inlet being distorted or damaged.

[68vitesse]

Have usedcLoctite 55, looks like dental floss.

Regards

Paul

[Guest]

Odd that plumbers across the nation use this, so it's reasonable to accept they know what they are doing day-in-day-out.

 

[PeteH]

Maybe I should add that My apprenticeship was over 50 years ago!. When you could still get a "good slap" for not making a "job" of it!.

[Guest]

16 minutes ago, PeteH said:

When you could still get a "good slap" for not making a "job" of it!.

Oh for those days to return, Pete !!

[Colin Lindsay]

43 minutes ago, classiclife said:

Odd that plumbers across the nation use this, so it's reasonable to accept they know what they are doing day-in-day-out.

 

There might be a difference between petrol and water, though - is it fuel-resistant?.... plus: even with plumbers there are some who use none, some who use a bit, and some who use tons to cover shoddy workmanship...

I suppose it's the same as with gasket sealer, many of us use gaskets alone while others use sealant as well.

[Guest]

 Hello Colin,

Sorry to hear about your "little" incident - glad you are okay and hopefully so will the TR6 in due course.

---------

Re suitability, this should help as flagged earlier:

Use for lines carrying acids (diluted), caustic alkali (diluted), hydraulic oil, natural gas, ammonia, diesel, inert gas, nitrogen, ethylene glycol, jet fuel, petroleum solvent, brine, gasoline, LP gases, steam, compressed air, heating oils, water, castor oils, helium. 

Regards.

Richard.

[Adrian Saunders]

Anyone know the torque for the nut? I tested a small section tonight and from nipped through to  (probably) over-tight, the olive doesn’t feel right. There are perfect looking, concentric, all around areas on the olive where it’s been compressed into the tube but, it just isn’t tight. It will turn a few degrees clock/anti-clockwise, though not all around. Should it remain tight even after disassembly? 

PS: If there’s products out there now that are suitable for sealing faces, great, I’ll use them. But, will they work with a loose olive? Sounds like something Popeye would say! 

[Guest]

21 hours ago, Adrian Saunders said:

no, 5/16” (not 8 mm)

Have you got the correct olive for the job ??

All olives when slipped on to a pipe will turn with minimal resistance they do not just sit rigid, it is the tightening of the compression joint that reshapes the olive to form a tight seal.

I have used 5/16" pipe with 8mm olive and never had an issue - in fact it is the perfect fit when fully tightened.

[Guest]

I do not think there is a torque setting for such, you just do it until it is tight and you can feel the nut biting fully.

Once you have tightened your compression joint properly you should not be able to remove the olive on the pipe when the nut is dismantled; as it will now have reshaped to the pipes circumference.

Is it possible that the pipe you are using is the problem, if you are experiencing the above issues ??

Have you actually tried to confirm that the joint may be fully tight and doing its job and by this I mean connecting the pipe and testing for fluid tightness ??

 

[Adrian Saunders]

Hi Classiclife, I tested with a tightened nut, from nipped to (probably) over tightened. Olives: I’ve tried two types, stepped that were in the kit and barrel that I swapped to after discovering a barrel type at the fuel pump. Def 5/16”, not 8 mm. After tightening I experience the loose olive. 

[PeteH]

Hi

Not wishing to decry anyone's ability. so please take this in the manner intended. Are you SURE it is a 5/16" olive? (7.9375mm) and not an 8mm masquerading as 5/16?. SOME suppliers will provide 8mm and tell you it will "take up". All it then needs is for the pipe to be at the lower end of it`s tolerance, which could be 5%? undersize. and you have the issue you describe.

[Guest]

10 hours ago, classiclife said:

Have you got the correct olive for the job ??

 

10 hours ago, classiclife said:

Is it possible that the pipe you are using is the problem,

Well, it has to be one or the other.

Good luck.

[Pete Lewis]

soft pipes will collapse and leave you a loose olive,  ive found this pretty common on fuel and plumbing  over the years  its not that unusual problem

on production to permanently seal threaded and seated pipes we used loctite 572  this takes time to clure and sets firmly  solve many small air leaks, we had a ultrasonic kit that picked up an ant farting at 50 paces ,but a jam jar of soft soap showed bubbles  it coud not detect

as for apprenticeships i started a topic way back back which died   here's me .. on the left  .the good looking one at our Commer apprentice school 3rd year looking after newbies.  clock in or face the music   and £2 9  3d  a week in 3rd year it was around £7 week and i ran my first side valve hairy Minx on that 

set of new India dunlop tyres £12  insurance £6 per year   those were the days 

Quote

 

 

 

[68vitesse]

So a years insurance was about a weeks wages, I would think it is less than that now.

Regards

Paul

[Colin Lindsay]

It all depends on who you insure, and in what vehicle.....

That you in the white coat, Pete?

Re olives: what kind is Adrian using? Some suppliers will send different shapes, but the only ones I find anyway suitable out of the selection in the photo (all supplied by Triumph suppliers!) are the symmetrical bottom left ones, which are a very tight fit on the pipes and usually require some kind of gentle warming to make them expand before they'll slide on. Once in place and cooled down they'll grip the pipe very tightly and nothing moves that isn't meant to.

 

[Adrian Saunders]

I was supplied top left, I switched to bottom left as that was what was on the short section out of the fuel pump. They collapse into the pipe which yields to the olive to, but is still loose. 

[Guest]

Safe to say that piece of pipe is history.

Are you using 100% copper or Kunifer pipe of which that is 90% copper and 10% Nickel - it is more resilient than copper and is preferable than using copper. If using copper where did you get it ?? Personally I have never seen copper pipe crumple under olive compression pressure like that.

I have to say that I am running out of suggestions at the moment; perhaps you can upload a few photos of what is going where to give a better idea - no matter how simple the task is. The olive bottom left is pretty much standard design, so it is a tried and tested design.

[Pete Lewis]

Colin the white coat was Ron the supervisor  im on the left , this was preparing a Commer TS3 for sectioning for the commecial show 

Its currently in coventry transport museum somewhere, last seen the  drive motor had failed

And  as for Olive im  feeling the soft pipe is the culprit  .

Pete

 

[Adrian Saunders]

Hmm. Indeed. It’s C106 copper which is 99.9% copper according to many suppliers. Can you bend Kunifer with a hand-held tool? I have this one.