PTFE tape or liquid airline sealant or something else

[123hotchef]

ok I have had enough tonight! cant get the new fittings on my extra air tanks to seal, tried Gas PTFE had at least 4 attempts not having it! never had a problem before with PTFE. Could it be the cheap china fittings? or should I use more tape!

 

[brightspark]

put some jointing paste on threads as well as with the ptfe

 

[123hotchef]

put some jointing paste on threads as well as with the ptfe

like boss white or furnox

 

[Rig Pig]

Are the fittings correct? You're not trying to fit taper and parallel or parallel x parallel together With tape? A lot of problems come from mixing threads, they bottom out or run out of threads before the threads bind and deform to form the seal.

 

[123hotchef]

Are the fittings correct? You're not trying to fit taper and parallel or parallel x parallel together With tape? A lot of problems come from mixing threads, they bottom out or run out of threads before the threads bind and deform to form the seal.

no mate all BSP threads

 

[brightspark]

boss white be ok

 

[123hotchef]

I am sure I have some of that if not I deffinatly have the furnox stuff that stinks in the tin

 

[Rig Pig]

no mate all BSP threads

Yes but BSPP or BSPT?

 

[Bill Edwards]

I'd tend to say that something is wrong if it won't seal with PTFE tape, just a couple of wraps will seal nearly any thread.
Are you sure it's not BSPP or BSPT as asked above, that would be the most obvious problem?

 

[123hotchef]

now you are asking lol well all the fittings are from toolstation they say bsp and the Ts are from china they say BSP too Is BSPT the tappered version?

Sorry I didnt know there was a difference, maybe the china Ts are different

 

[WorkshopChris]

tried Gas PTFE

Is that the thicker one designed for 2 wraps, i dont use it and stick to the traditional thinner original ptfe tape.

 

[Rig Pig]

Yes the taper and the parallel fittings will happily screw together but may never bind to form the seal, it just runs out of threads.

 

[123hotchef]

Is that the thicker one designed for 2 wraps, i dont use it and stick to the traditional thinner original ptfe tape.

yes mate I tried 3 and 4 wraps to no avail! never had a problem with it before the thinner stuff gets messy after a while lol

 

[123hotchef]

Yes the taper and the parallel fittings will happily screw together but may never bind to form the seal, it just runs out of threads.

they are all non tappered just measured them

 

[Rig Pig]

they are all non tappered just measured them

Then they will need a dowty or copper washer to form the seal on the shoulder.

 

[123hotchef]

I have plenty of copper washers no dowty ones that size though it is all 1/2 to 1/4" bsp so the copper washer will sit inside the bush or socket before the thread is screwed into it, funny I have never had a problem before

 

[voipio]

You need to think where it is the seal actually occurs. Putting PTFE or other sealing materials on parallel threads merely shears the material when the joints are screwed together and tightened, tearing up the material and causing leaks. Tapered threads are really the only ones that work with PTFE tape. Parallel threaded pipework normally relies either on some sort of sealing washer, or is used to hold sealing surfaces together e.g. cone joints on oxygen and acetylene gas cylinders.

See e.g: http://www.ralstoninst.com/news/story/the-difference-between-npt-bspp-and-bspt-seals

 

[optima21]

I've used loctite 55 in the past

http://www.loctite.co.uk/pipe-sealing-9886.htm

 

[123hotchef]

are these BSPP OR BSPT? http://www.toolstation.com/shop/Plumbing/d20/Compression/sd2697/Brass+Socket/p24305

 

[Tim.S]

I would try Loctite 55 which is a string like thread seal or Loctite 577 which is a liquid thread seal that sets hard, both are expensive but very good.