Sealing hydraulic threads

DublinDilbert

Hi all,

Looking for some practical hydraulic connection experience.

Working on a prototype system which has a max of about 30 bar pressure. Am I ok to use regular loctite thread lock on the hydraulic fittings? (3/8 and 1/4)

Hard to find the specific loctite, have lots of the normal thread lock stuff around.

Also I have a mixture of 1/4 bspp and m10 connections, they thread together fine, will I have problems dealing the threads?

Thanks

Dawggone

DublinDilbert wrote: »

Hi all,

Looking for some practical hydraulic connection experience.

Working on a prototype system which has a max of about 30 bar pressure. Am I ok to use regular loctite thread lock on the hydraulic fittings? (3/8 and 1/4)

Hard to find the specific loctite, have lots of the normal thread lock stuff around.

Also I have a mixture of 1/4 bspp and m10 connections, they thread together fine, will I have problems dealing the threads?

Thanks

Do you really need loctite? 30 bar is very low pressure.
Standard hydraulic connections shouldn't need loctite at that pressure.

DublinDilbert

Dawggone wrote: »

Do you really need loctite? 30 bar is very low pressure.
Standard hydraulic connections shouldn't need loctite at that pressure.

Thanks, yea I know it's low pressure, but they are parallel threaded fittings so no o-rings or dowty seals.

Want to just make sure no leaks from the threads

tomwaterford

DublinDilbert wrote: »

Thanks, yea I know it's low pressure, but they are parallel threaded fittings so no o-rings or dowty seals.

Want to just make sure no leaks from the threads

If they are hyd fittings once they match they shouldn't leak

DublinDilbert

tomwaterford wrote: »

If they are hyd fittings once they match they shouldn't leak

That's why i was looking for advice. They are the same parallel BSP threads which would be used in plumbing fittings. So they would definitely need thread sealer on them so they will seal correctly.

Waffletraktor

DublinDilbert wrote: »

That's why i was looking for advice. They are the same parallel BSP threads which would be used in plumbing fittings. So they would definitely need thread sealer on them so they will seal correctly.

Small amount of ptfe tape?

DublinDilbert

Waffletraktor wrote: »

Small amount of ptfe tape?

Yea trying to avoid ptfe as it can mess up valves if a but gets loose.

I know I have regular loctite thread lock and seal down in the garage, just don't want to use if I'll have to clean it off and use something else.

I'm sure one of the places that does hydraulic seals would sell something at the trade counter.

johnny122

DublinDilbert wrote: »

Yea trying to avoid ptfe as it can mess up valves if a but gets loose.

I know I have regular loctite thread lock and seal down in the garage, just don't want to use if I'll have to clean it off and use something else.

I'm sure one of the places that does hydraulic seals would sell something at the trade counter.

If you are using hydraulic fittings they are rated for up to and above 200bar. 30 bar is nothing to them. There should be no need for ptfe or locctite on these if you are using then correctly ( wouldn't be much good at 200bar ) if you have two fittings connecting together then you either have two opposing cones meeting each other in which case a squeeze will seal them or you have a male thread going into a housing of some sort in that case you need a dowty washer to seal it. Ask the lad you bought them off.

patsy_mccabe

30Bar is very low. Are you sure about this? 150bar would be more standard.
As for the fittings, parallel threads are standard on all fittings, but it's not the threads that provides the seal. It what going on inside that does this. Loctite and PTFE should not be used on threads.
The best seal of all is an o-ring. I've seen systems using pressure up to 1200 bar with o-rings.

DublinDilbert

Thanks guys, it is quite low pressure. It's a prototype system to control a hydraulic brake. I have some proper hydraulic fittings that as you say seal on the cones or with dowty washers.

But I needed to get back to m10 fittings similar to brake lines, the hydraulic guys had nothing to help with this. So I got some brass fittings and the whole lot assembles grand. But I need to seal the threads up. Ptfe would probably do, but want to avoid it if possible.

longgonesilver

Are the brass fittings rated for 20 BAR?

Only way to really know about sealing is to set up a trial joint and test it under pressure.

my3cents

If you have to resort to using ptfe then try using the much thicker one wrap ptfe tape used for gas.

gctest50

DublinDilbert wrote: »

Thanks guys, it is quite low pressure. It's a prototype system to control a hydraulic brake.......

You might want to organise it so the hydraulic pressure releases the brake ( for a nod towards fail-safe ) - cut the hose and the brake should come on


Would this sort of thing be better ?

patsy_mccabe

Machine up a manifold, keep the hydraulic fittings at one side and the brake fittings on the other.

fastrac94

Loctite 55 worth a try,seals everything round here and never any comeback..

jmrc

M10 is available to 1/4" BSP in adapters if you call to the correct supplier. needs to be specialised supplier.

dont take risks with brakes... even on a prototype.
Call the boys in Micro hydraulics in citywest, look for Neil, they will help you solve the problem.
As stated above, loctite or PTFE tape can get loose and get caught in the valves...

For the record, I have used Micro in the past, found the lads very helpful. not associated in any other way.

thank you

tomwaterford

DublinDilbert wrote: »

That's why i was looking for advice. They are the same parallel BSP threads which would be used in plumbing fittings. So they would definitely need thread sealer on them so they will seal correctly.

They won't need sealant....as the fittings are set up to sit into one and other and the treads only keep it tight

If your leaking through a male-female connection your connections are wrong

patsy_mccabe

Exactly. You shouldn't use tapered thread fittings either for hydraulic functions.

OP have a look through this link. You might find what you need.
http://www.parker.com/Literature/Tube%20Fittings%20Division/EO_&_EO-2_Metric_Bite_Type_Fittings.pdf