Air pipe on old lorry?

I have a Horsebox on a 1986 Leyland Road Runner chassis, (7.5 tonner like a modern Daf 45).
The inspection people have just failed it for having a "braze" on the air
line from the compressor to the first reservoir. I havn't had a close look yet, but someone may have replaced a length of the original steel with copper. My local service guy thinks it is OK and an unreasonable fail, but obviously sees it as a rats nest job and doesn't want to touch it. I just need to get it fixed. Pipe is about half inch. I did wonder if it was a soldered repair, which might be more reasonable grounds for failing.
One difficulty is access to the compressor joint (luton stops the cab from tipping). System pressure is about 6 bar. Can't use polymer (like trailer curlies) under the chassis apparently. Does anyone know what materials are permitted, e.g. copper, stainless, other alloys, instead of steel? Obviously it has to have a suitable pressure rating, presumably 12 bar or higher. There is already one compression joint in the line (apart from at the ends). So one strategy might be to cut forward of the braze, remove the brazed section to the compression joint, and make up a new piece from the old compression joint and use a second joint to connect it to the line to the compressor. But that assumes the existing front (copper?) is actually OK. I know about galvanic corrosion with mixed materials.
There's a local branch of Pirtek, and I'm told they can make up just about anything, but I'm not sure if they will know for sure the legal requirements for lorry air lines. I havn't spoken to the local DAF agent yet, but I imagine it's not a stocked spare, so they'd just get a special made anyway.
TIA Steve
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they were saying:

<all left in unsnipped, because cross-post added to uk.rec.cars.maintenance - a few truck drivers there who may well know>

I'd be _gobsmacked_ if they didn't.

You may be surprised. It's gotta be worth a call.
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gurgled happily, sounding much like

We have run several Daf 45's / Road runners.
The airpipes and power steering steel pipes indeed like to rust for fun if not kept coated with grease. Daf use captive gland nuts with the pipes flared at each end, which rust internally. When you try to un-do them, twists the pipe off. :(
I've used hydraulic hose & fittings made up by my local agri parts shop to replace the pipes entirely. Certainly ok for oil, can't see why not for the air compressor.
Can you access the compressor at all with the cab down?
Tim.
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gurgled happily, sounding much

The cab should be able to tilt. A luton I drove many years ago had the floor panel of the luton head loose so it could lift up to enable tilting the cab. Of course many horse boxes are backyard conversions and this may not be the case here.
Just on the off chance that you have a BH postcode, there's an excellent place in Poole called Thread and Pipe, I recommend them.
Steve
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Basically, if they can't tilt the cab, they're going to have all hell on to try and do it.
--
Conor

I only please one person per day. Today is not your day. Tomorrow isn't
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I had wondered if this might be the case, but I suspect not. The luton has "fitted carpet" and it looks to me like the steel framing would get in the way even with the floor out, but it's difficult to be sure without trying. Also, the cab tilt/release mechanism has been disabled in some way that I havn't spotted yet, but while I am grovelling around underneath I will have more of a look around. Apart from the cab issue it looks to be quite a good quality conversion. If the worst comes to the worst, I could always take an angle grinder to the luton because we are not that likely to be sleeping in it.
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Hi "newshound"
I have been working for 10 years as a Mech. engineer in a competitor lorry plant here in Italy, so I express my opinion about you problem:

The pipe has to cope with high temperature of the compressed air (no polymer for the first 2 meter from the compressor) and quite high vibration. So I wouldnt' allow any braze on it, neither I would change the path and the holding position of it ( it is carefully engineered) Its metallic nature also serve as a cooling device for the air going to the following plastic pipes, so don't change it with any polymer, no matter any thick or resistant type you find.

First choice (for fatigue life) is copper, second steel (cheaper)

Usually you use work hardened copper 2mm thick.

May be or may be not, the issue is vibration resonance (It had been broken before, hadn't it ?), so any change may affect it life (expecially if the new coupling is not near an holding bracket).

No problem here with galvanic corrosion.

Let them know what your thinking to do, and follow any advice they give you.
P.S. usually you have in the first meter of the pipes from the compressor a dampening resonator for noise reduction (it depends on you particular vehicle, I dont' know). If it had been fallen with the former pipe section, may be it had noy been restored (judging from the crude repair you were undergone)
Good luck
Paolo
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Paolo
Excellent points, thanks very much. There doesn't seem to be any damper near the front, but half way back the pipe goes through about 10 cm of thick wall rubber tube clamped centrally to a bracket, so that would provide some damping. There's a similar length further back without a bracket, and I wondered if there might be a bracket missing. Thanks to your prompt I will have a much closer look.
Steve
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We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Newshound"

You'd be surprised at the resonant effects on pipes running along chassis, which makes it all the more important to secure them well - firmly and loosely, as appropriate.
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Just had a thought about this. There should be a flexible pipe section somewhere between the last pipe mount on the engine/gearbox, and the first mount on the chassis. If there's no flexi section, then the new pipe will crack quite quickly. It's normally a steel reinforced/braided flexi section.
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newshound wrote:

My guess is that the inspector failed your truck because he wasn't sure if the brazed joint was secure, not because he knew for certain that there was something wrong with it. And it's difficult to tell without seeing it. My JCB digger has a good brazed joint in one of the hydraulic pipes. That holds about 120 bar maximum working pressure.
Chris
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Christopher Tidy wrote:

I think Signor Di Marcos reply covers all the bases. Quite the best reponses I have seen here in ages.
I had a brake pipe fatigue on me..just a hydraulic one, off an after design installed brake servo..and it ain't fun.
Don't take chances on brakes.
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We were somewhere around Barstow, on the edge of the desert, when the
saying something like:

Good, wasn't it?
It's the usual bodgy repair done by a backstreet fecker who doesn't know or think about the implications.

Especially pipework and cylinders.
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were saying:

Don't forget that wagon air brakes work the other way round to car hydraulic brakes. Air brakes are held off by the air pressure, and spring- loaded on, whilst hydraulics are normally off and pressed on.
If a hydraulic brake pipe fails, you have no brakes. If an air brake pipe fails, you have full brakes.
A 7.5t wagon full of horse(s) with very firmly applied brakes which can't be released is a right pita, but it's a different kettle of glue to one with no brakes.
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Adrian wrote:

I presume this is why you sometimes see a great long skid mark the width of a lorry tyre? i.e. airline pops off and a wheel on the trailer just locks.
--
Cheers,

John.

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Removal of the pump *is* a bugger and usually (If you have long arms) can be done from underneath IIRC. A pit would be a good way of getting to it and make the job easier. Chat to your local garage to see if they can assist.
Alternatively (And this ain't gona be a quick fix) if you plan on keeping the box you'll have to have the body lifted clear enough to allow cab tilt to remove the tanks for proper repair. Having done this myself in the past it is a long but worthwhile job if you are keeping the box. The only alternative is to have the "Luton" section modified for removal when servicing. Something a friend had done by a "Man that can" and was very professional.
Just be thankful you aren't in a "Congestion Zone" area and have to fork out for a conversion kit at around 3k fitted !
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THis motor will have "air over hydraulic brakes" not pure air.Pipe originally would be Bundy tube.If the main agent can`t get a genuine spare,and I can`t think of a reason why he wouldn`t be able to,he would be able to make a new pipe up with a larger version of the flaring tool they use for car brake pipes.
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Brazing is not deemed a satisfactory repair, in terms of HGV/PCV inspection.
A suitable repair would be either complete renewal of the pipe, or using compression fittings and a new bit pipe to replace the bad section. You can use copper or steel for the replacement. I don't think there is anything in the testing manual about the pipe having to be metal, however rubber/plastic pipes will most likely fail due to heat (it's not unknown for airdriers to go up in flames if the cooling loop is removed on certain vehicles).
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Thanks for all the helpful replies. Also, I got under it today with a decent torch so now have a clearer picture.
DAF agent will just sell the pipe for making up to fit, 50 odd for 3 metres. As someone says, it looks like I can just about get spanners on the compressor from underneath, even without a pit. I think my first port of call will be Pirtek, see if they know what the end fittings need to be and what pipe they suggest. Once I have a replacement in my hands I'm not too nervous about taking the old one off, recognising as someone says that this is likely to be destructive. I'm sure the reason my local repair people don't want to touch it is the possibility that they end up with a vehicle stuck over their pit until they lift the box off. The box seems to be bolted down with about three (accessible) fixings on each chassis leg, so not too daunting to remove, given a suitable crane. Not sure how far it has to lift to let the cab tilt. The rear fitting is right at the back and perhaps it could be pivoted on that. But the cab tilt mechanism has been locked somehow and I can't see where, for the moment.
Useful to hear that copper is permitted. It's fairly obvious from the irregular bends at the front that this is a "home made" repair, quite possibly put in with the cab down. I've already sprayed the joints with WD-40!
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Naaaah, they dont want to touch it cos hoss boxes are a bastard to work on, the trucks engines are made to be serviced from the top and sides, hence the tilting cabs,
then someone goes and builds a luton body over the cab roof and your only access is from the bottom, or if your lucky a few access panels in the cab floor that have been cut to get at components that have failed.
the better hoss boxes have as others have said, a lifting floor in the luton, this will let the cab tilt a little way and is often enough for access to most major components, fit a removeable front panel to the luton, and the cab can be tilted fully and people will want to work on the thing again.
when i was the yts bod at a commercial garage, a hoss box was brought in after suffering an engine fire, had to drop the front axle and take the engine out from below, job took almost 3 months because the mechanics would do everything they could to avoid working on it, most of the work was done by me, as i was skinny back then, so only my arms could reach up between the engine and chassis rails to get at connections on the top.
almost as bad as when i got called out years later to a car transporter with a water pump faliure, middle ofa hot summer, couldent tilt the cab as it was loaded, and couldent run the engine long enough to get all the cars moved back to allow the overcab one to be shifted and that bit of the decking lifted.
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