Board logo

Sealing oil pipework
SJ - 7/4/18 at 03:46 PM

I'm about to finally fit my remote filter. Anyone got experience of the best way to avoid leaks in the pipework joints? I have seen recommendations of the use of PTFE tape on the bsp screw fittings. Mine have rubber lipped washers which look like they will seal well but it will be a PITA if they leak.

Any advice welcome!

Thanks

Stu

40inches - 7/4/18 at 03:55 PM

Possibly liquid PTFE, should be available at your local plumbers merchant?

steve m - 7/4/18 at 04:35 PM

BSP are taper threads and thus self sealing, so no additional tapes or threadlock are required

[Edited on 7/4/18 by steve m]

SJ - 7/4/18 at 04:56 PM

Having done a bit of Googling, looks like Dowty washers, which I have are the correct thing to use.

I don't think the threads won't seal on their own, tapered or not. The male to male fittings go all the way in to the take off and filter hosing so if the threads are tapered they don't lock before all the fitting is fully screwed home.

Thanks

Stu

rodgling - 7/4/18 at 07:08 PM

Threadlock does a good job for this.

SJ - 7/4/18 at 07:47 PM

quote:

Threadlock does a good job for this.


Do you mean something like Loctite 243?

rodgling - 7/4/18 at 07:49 PM

quote:
Originally posted by SJ
quote:

Threadlock does a good job for this.


Do you mean something like Loctite 243?


Yes, exactly (or in my case the non-branded equivalent).

SJ - 7/4/18 at 07:51 PM

Thanks - pretty sure I have some in the garage somewhere.

daviep - 7/4/18 at 08:02 PM

BSP are available in both parallel and taper, I would always use a sealant whether tape or paste on tapered fittings. You seem to have identified that you have parallel fittings (they screw in all the way), the dowty washer is a very reliable seal no need for additional sealant. Only thing to check carefully is that the face the dowty seals against on the block is nice and flat and smooth.

Cheers
Davie

SJ - 7/4/18 at 08:11 PM

Thanks Davie

Andybarbet - 7/4/18 at 08:54 PM

+1 For dowty seals.

I'm a hydraulic fitter & use them a lot at really high pressures too.

SteveWalker - 8/4/18 at 01:07 AM

Back in the early '90s, I did the control system design for an industrial compressor for ICI. Their specs were decades out of date. They called for instruments to be fitted with BSP parallel fittings ... with "greased leather washers"

perksy - 8/4/18 at 08:26 AM

Had Dowty seals on my dry sump system and they seemed fine

I'm always weary of using a chemical/threadlock or ptfe on an oil system, a mate had a very expensive XE go bang on the dyno and after stripping it down it was found to be oil starvation caused by a 'lump' of threadlock that had found its way into the oil gallery

SJ - 8/4/18 at 09:01 AM

Thanks guy. Dowry seals it is then.

daviep - 8/4/18 at 09:15 PM

quote:
Originally posted by perksy
Had Dowty seals on my dry sump system and they seemed fine

I'm always weary of using a chemical/threadlock or ptfe on an oil system, a mate had a very expensive XE go bang on the dyno and after stripping it down it was found to be oil starvation caused by a 'lump' of threadlock that had found its way into the oil gallery


You are correct to heed caution but the failure was not caused by threadlock or PTFE, the failure was caused by somebody applying said products incorrectly. There are quite specific methods to apply either PTFE tape or liquid sealants to prevent contamination of the system. Personally I'd stop worrying about said products and start worrying about the competence of the people working on my expensive engine.

Depending on the pressures involved and the materials the parts are made of you may achieve a seal without applying a sealant, but at higher pressures or if the parts are stainless then it is almost impossible without sealant.

Cheers
Davie

rodgling - 8/4/18 at 09:55 PM

quote:
Originally posted by daviep
You are correct to heed caution but the failure was not caused by threadlock or PTFE, the failure was caused by somebody applying said products incorrectly. There are quite specific methods to apply either PTFE tape or liquid sealants to prevent contamination of the system.
Cheers
Davie


What are the specific methods? I've always just used a very small amount, on the part of the thread quite far from the open end - this has worked for me.

[Edited on 8/4/18 by rodgling]

daviep - 9/4/18 at 05:54 AM

That is pretty much spot on for paste type's. For normal white PTFE tape you should be using 3-5 wraps applied clockwise (same way you'd screw on a nut) with good tension so it wraps nice and tight, starting behind the first thread. No tape should overhang the nose of the fitting, if it bunches up as you screw the fitting in then you have too much tape or not applied tightly, clean and start again. As a rough check for tapered fittings they should screw in by hand 3 turns before you put tape or sealant on, a large deviation should raise concerns.

Cheers
Davie