Nickel plating copper pipe - problems?

I read in Rankine Kennedy 'The Book of the Motor Car' - about 1918 - thus:

Rudge racing experience at Brooklands has proved to them that nickel plated copper pipes invariably fracture, and following that experience they have discontinued plating copper petrol and oil pipes.

I have not come across this problem before, but perhaps you have?

It sounds like embrittlement, of which I have experience with high tensile steel only.

I look forward to learning more from fellow contributors.

Regards, Tim

Hi Tim, have come across something similar to this on motorcycles......

but I fear it was because the pipe was held to tight when it needed a little flex or just too dam loose so vibration was the problem........

this was was on plain and plated pipe's......

where poss I try to use a rubber sleeve under a metal retaining bracket to stop this kinda thing on my repairs........

hope this helps Clogs

I am aware of failure when the pipe run is too tight or too short etc, but this quote refers to curing failure with Ni plating by not plating. The photo with the article (not of a racing machine) clearly shows a pipe with a generous sweep at both ends, and a horizontal loop, as you might expect, but as this is not a Brooklands picture it may not be relevant.

Cheers, Tim

Cunifer (copper, nickel, iron) pipes are very widely used of course in braking systems, so it seems unlikely that embrittlement would be an issue? Different having plating rather than an alloy admittedly but not clear what the suggested mechanism could be if it was in fact a valid explanation for their failures. You have to wonder....

Murray

Could it be that Hydrogen got at the Copper during electroplating? If so better chemistry may have fixed the problem shortly after, which is why we've never heard of it!

Dave

Muzzer - a bit of explanation which might help -

The classic cause of embrittlement when plating (on steel, usually) relies on the electrical process - as well as the protective metal, hydrogen is produced, and can be trapped within the surface of the plated object. Then when the part is put under a tensile load, the hydrogen can seep between the crystals of the metal until failure occurs. With zinc plate on HT bolts, it can take a few minutes after the bolts are tightened normally. Ping, and the heads goes flying across the shop. Quite exciting when it happens to a room full of motorcycles awaiting final packing ...

I hope this helps to explain what might have been the cause of Rudge's problems, but does it happen with copper, or just steel? Come on you metalurgists.

Regards, Tim

Silly old duffer is on my wavelength with his comment about hydrogen.

One further factor in the debate is that modern Nickel plating uses a different array of chemicals to that used in the vintage era. Mainly to produce a bright surface rather than the 'dull nickel' so beloved of vintage restorers.

Tim

I'm aware of hydrogen embrittlement in steel but not heard of it in copper etc.

Wikipedia shows references that appear to claim copper (and others) is immune to embrittlement. The melting point of nickel is 1455C and copper is 1085C, so immersion in liquid nickel seems rather unlikely.

But according to this guy it IS possible - if you get the copper up to 400C so the hydrogen can diffuse at a sufficient rate.

Could something else have sufficiently small molecular mass to be able to diffuse in at the relatively low temperatures encountered during plating? Can't be many candidates. Can't be nickel itself, as it has a molecular mass of 59.

I'm still dubious.

Edited By Muzzer on 04/09/2017 20:42:40

The coating was done at a low temperature, well below boiling point (of water), using electricity and a bath of nickel salts. Hydrogen ions are exceedingly small, not having the clutter of neutrons hanging on. Helium, next larger (and not found in electroplating at all) has a nucleus more than twice the size.

I too am dubious, Muzzer, that is why I asked the question. But I am sure that some model maker, somewhere, has used nickel plated copper pipes ...

Cheers, Tim

May I offer a non-chemical hypothesis Tim ?

The Young's Modulus of Nickel is considerably higher than that of Copper; and it is [I think] also less ductile.

Consider a plated tube assembly [i.e. with end fittings]: This will be stiffer than an uplated one ... until the plating cracks under vibration ... and then 'stress corrosion' rapidly takes over.

My unsubstantiated 'memory' says that the failures were at the stress-raiser, where the pipe enters or exits a fitting.

MichaelG.

Then vibration is the culprit, I have always repaired copper connections with a loop and had no more problems. Occasionally take them down and anneal them. Boat engines are prone to this and of course go pop in the dark.

Clive

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Yes indeed, Clive ... but I'm suggesting that the Nickel plating exacerbates that underlying problem.

MichaelG.

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Edit: a couple of minutes browsing found this:

https://www.copper.org/applications/industrial/DesignGuide/performance/scc03.html

... The designer may also elect to control the environment by plating the spring component with either Sn or Ni. Such protective coatings are effective only when the part is 100% covered and the plating is free of porosity, voids, cracks, and other defects which would impair its integrity. Because of the difficulty of obtaining defect-free plating, invasion by unwanted species is a risk, so alloy selection is the usual method to combat SCC.

... so I may be on the right lines.

Edited By Michael Gilligan on 04/09/2017 23:03:16

I would buy the theory that a stiff plating over a ductile pipe would be vulnerable to cracking, which would then create points of greater flexure leading to work hardening and cracking of the pipe.

Cheers, Neil

My hypothesis is duly upgraded, by peer-review, to a theory

MichaelG.

Chrome plating can start fatigue cracks, stopped being used back in the fifties on m/bike frames and suspensions. Nickel was thought to be safer ! Chrome cracks and starts fatigue cracking. I have seen hot-dipped zinc chassis crack, but the reason may not be the same.

I've had repeated experience over the years of chrome plated metal fuel lines on vintage Harley Fergusons cracking, usually at the beginning of the flare on the end. Both copper and steel tubes have done this when chrome plated. The fuel pipe has an anti-vibration loop in one end, the end end that usually lets go. Unplated or cad plated (when you used to be able to get it) fuel lines don't seem to have the same cracking problem.

I also remember back in the 1960s-70s that specialist UK cafe racer builders Paul Dunstall and the Rickman brothers used nickel plated frames, as chrome was said to induce cracking. Just my .02c worth.

Thanks, everyone, I think you have now confirmed my view that it was the same sort of process as I witnessed with embrittlement of plated steel.

Incidentally, the major problem with chrome plating of motorcycle frames and similar outdoor structures, is that the plating will not cover anywhere which you cannot touch with a golf ball. That means that however good the standard of plating, there will be rust developing below the headstock, and between any of the frame structure where tubes meet at less than about 150 degrees. And of course, as this rust would develop in the guarantee period (*) the manufacturers and dealers were very keen to avoid it. Nickel on its own throws much better (that is the term for it) and so you could get away with it.

*At one stage it was suggested in the Service Dept that the N*rt*n Come & go guarantee should be changed to '500 yards or 5pm, whichever is the sooner'. Oh happy days of yore.

Regards, Tim

Edited By Tim Stevens on 05/09/2017 16:16:39

Or use prohibitally expensive oxygen free copper and embrittlement wouldnt be a problem.