Attaching high pressure braided hose to metal pipe

Attaching high pressure braided hose to metal pipe

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Discussion

Sensibleboy

Original Poster:

1,141 posts

124 months

Monday 23rd February 2015
quotequote all
I've fitted an electro hydraulic power steering pump from a Citroen Saxo to my car and it's currently plumbed in using a compression fitting (on the high pressure side) between pump and the original pipe that goes under the engine to the rack. The problem is I'm not totally confident that the compression fitting on the flexi hose is the best way of plumbing it all together.



A screw in fitting is available to easily fit a braided hose directly to the pump but how could this be connected properly to the metal pipe under the sump? It's not obvious to me how this could be done and what sort of fittings are available to do this. Could the metal pipe be swaged somehow to allow the hose to be fitted?



Any ideas?




griff 200

509 posts

192 months

Monday 23rd February 2015
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If it's a steel pipe I would just bronze weld a fitting on the pipe ! You may need to cut a fitting in half drill out to make pipe fit inside before welding.

Sensibleboy

Original Poster:

1,141 posts

124 months

Monday 23rd February 2015
quotequote all
Now that's a great idea. Weld on AN-06 adaptors are easy to get hold of. That would do the job perfectly as well. It's obvious when I think about it. Cheap too ! I just hope my mechanic can weld small items!

anonymous-user

53 months

Monday 23rd February 2015
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Make sure you use proper double (or triple) braided hydraulic hose, and not just generic "braided motorsports" hose! Pressure spikes of 200 to 300 bar are possible when the rack hits the end stops!

stevieturbo

17,229 posts

246 months

Tuesday 24th February 2015
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Just weld or machine something from steel or stainless.

A friend did use a normal compression olive before on one car, and it has never failed....but it scares me !

PAS fluid is flammable, so dont muck about.

andyiley

9,102 posts

151 months

Tuesday 24th February 2015
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In the first instance compression fittings (assuming they are proper high pressure compression fittings) are MORE than capable of the pressures in a power steering systems.

In your other question, without seeing closer the other fittings, it is virtually impossible to come up with alternatives.

In answer to another suggestion above, one thing I would NOT be doing is welding a fitting onto a high pressure hydraulic system in an engine bay!

One more thing, if I am seeing your first pic correctly, you have fitted the union on the solid pipe FAR too close to the bend to give a 100% reliable connection.

Edited by andyiley on Tuesday 24th February 08:03

BritishRacinGrin

24,602 posts

159 months

Tuesday 24th February 2015
quotequote all
andyiley said:
In the first instance compression fittings are MORE than capable of the pressures in a power steering systems.

In your other question, without seeing closer the other fittings, it is virtually impossible to come up with alternatives.

In answer to another suggestion above, one thing I would NOT be doing is welding a fitting onto a high pressure hydraulic system in an engine bay!

One more thing, if I am seeing your first pic correctly, you have fitted the union on the solid pipe FAR too close to the bend to give a 100% reliable connection.
I agree with all of this, I'd want to know exactly what the pipe is made of before making any attempt to weld something onto it. There is no cause to suggest that compression fittings aren't up to it, OEMs use crimped fittings all the time.

Sensibleboy

Original Poster:

1,141 posts

124 months

Tuesday 24th February 2015
quotequote all
andyiley said:
In answer to another suggestion above, one thing I would NOT be doing is welding a fitting onto a high pressure hydraulic system in an engine bay!

Edited by andyiley on Tuesday 24th February 08:03
Do you mean physically welding the pipe while it's still attached to the car (it would be removed to do any work on it) or do you mean I shouldn't even considering using such a fitting?

andyiley

9,102 posts

151 months

Tuesday 24th February 2015
quotequote all
No, I mean welding anything into a system that will contain high pressure hydraulics.

To EVEN attempt it I would need to see the qualifications and training records of the "coded welder" who was going to attempt it, I would then insist on a 200% pressure test and an x-ray inspection of 100% of the weld, otherwise FORGET IT.

You are going to put high pressure hydraulic fluid (that is explosive when in a high pressure mist) through it in an engine bay remember!

anonymous-user

53 months

Tuesday 24th February 2015
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I suspect a few people might be slightly over estimating the performance of that little Saxo PAS pump (actually a std HPIcanada "powerpack")!

If we assume that pipe is 10mm ID, with 100bar on it (saxo pump can only manage about 80bar steady state) that's just 785N trying to rip the fitting off, (~80Kg for normal people). And so whilst, Yes, it does need to be welded or brazed properly, it's certainly not beyond the remit of a decent "hobby" welder.

annodomini2

6,860 posts

250 months

Tuesday 24th February 2015
quotequote all
Max_Torque said:
Make sure you use proper double (or triple) braided hydraulic hose, and not just generic "braided motorsports" hose! Pressure spikes of 200 to 300 bar are possible when the rack hits the end stops!
Probably higher for a few ms.

stevieturbo

17,229 posts

246 months

Tuesday 24th February 2015
quotequote all
BritishRacinGrin said:
I agree with all of this, I'd want to know exactly what the pipe is made of before making any attempt to weld something onto it. There is no cause to suggest that compression fittings aren't up to it, OEMs use crimped fittings all the time.
A proper crimped hydraulic hose is slightly different than a DIY compression fitting.

stevieturbo

17,229 posts

246 months

Tuesday 24th February 2015
quotequote all
andyiley said:
No, I mean welding anything into a system that will contain high pressure hydraulics.

To EVEN attempt it I would need to see the qualifications and training records of the "coded welder" who was going to attempt it, I would then insist on a 200% pressure test and an x-ray inspection of 100% of the weld, otherwise FORGET IT.

You are going to put high pressure hydraulic fluid (that is explosive when in a high pressure mist) through it in an engine bay remember!
bks, even a fool could weld something up....as I've proven many times

The steel hoses would burst before even my welds !

andyiley

9,102 posts

151 months

Tuesday 24th February 2015
quotequote all
You go for it then Steve.

griff 200

509 posts

192 months

Tuesday 24th February 2015
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if you are going to bronze weld there may well be coating on the fitting and the pipe so file down to get down to clean steel. Fitting as pic. As you have around 1700psi you properly only need single wire hose compression fitting should be fine but really depends if the steel pipe is designed for them ie correct size and wall thickness any way good luck. Richard

stevieturbo

17,229 posts

246 months

Tuesday 24th February 2015
quotequote all
andyiley said:
You go for it then Steve.
As said, Ive done it plenty of times, and my own car has been running welded fittings for over 10 years.

Disco_Biscuit

837 posts

193 months

Wednesday 25th February 2015
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Just go to Pirtek and get correct hose made

Sensibleboy

Original Poster:

1,141 posts

124 months

Wednesday 25th February 2015
quotequote all
Pirtek supplied the hose that's currently fitted.

andyiley

9,102 posts

151 months

Wednesday 25th February 2015
quotequote all
stevieturbo said:
even a fool could weld something up....as I've proven many times
I should remember that precise wording if I were you, it may just come back to haunt you!

one eyed mick

1,189 posts

160 months

Wednesday 25th February 2015
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Re weld/ braze hyd fittings I have seen many flange fittings and threaded fittings simply brazed or welded the secret is proper prep to ensure zero inclusions in the joint . The stuff I'm talking about was on heavy excavation or lifting gear with pressures up to 450 bar never saw one fail in 20 years or so but saw many crimped or swaged hoes blow