02GF74
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| posted on 23/5/08 at 08:18 AM |
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rather interesting SVA fail...
.... I wonder how many inspectors spotted this! 
quote:
Copper brake tube was clipped with the original Cortina bent metal bits on the rear axel - this would fail due to dissimilar metals corroding
the copper tube; glad he spotted this ( original Ford brake tube is steel, so no probs);
but then the end pieces are dissimilar metal too!?!?!?!
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kendo
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| posted on 23/5/08 at 08:46 AM |
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Tosh!!!
What a load of tosh!
It just shows that a little knowledge is a dangerous thing. When galvanic corrosion occurs between dissimilar metals it is the most reactive (anodic)
metal which corrodes.
Steel is more anodic that copper so it is the steel which will corrode.
He obviously didn't listen in his science lessons.
The list below illustrates my point.
Table 1. Standard Galvanic Series Of Common Metals In Sea Water
(Ranked from most corrodible to least corrodible)
Anodic End (most corrodible)
Magnesium
Magnesium Alloys
Zinc
Galvanized Steel
Aluminum 5052H
Aluminum 3004
Aluminum 3003
Aluminum 1100
Aluminum 6053
Alcad Aluminum Alloys
Cadmium
Aluminum 2017
Aluminum 2024
Low-carbon Steel
Wrought Iron
Cast Iron
Ni-Resist
Type 410 Stainless Steel (active)
50Sn-50Pb Solder
Type 304 Stainless Steel (active)
Type 316 Stainless Steel (active)
Lead
Tin
Muntz Metal (C28000)
Manganese Bronze (C67500)
Naval Brass (C46400)
Nickel (active)
Inconel (active)
Cartridge Brass (C26000)
Admiralty Metal (C44300)
Aluminum Bronze (C61400)
Red Brass (C23000)
Copper (C11000)
Silicon Bronze (C65100)
Copper Nickel, 30% (C71500)
Nickel (passive)
Inconel (passive)
Monel
Type 304 Stainless Steel (passive)
Type 316 Stainless Steel (passive)
Brazing Filler Metals (silver-copper-zinc alloys)
Silver
Gold
Platinum
Cathodic End (least corrodible)
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BenB
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| posted on 23/5/08 at 08:58 AM |
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True- worst case scenario would be the clip corroding resulting in a lose pipe.
Being Ford the clip would have rusted away long before galvanic corrosion occured 
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mistergrumpy
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| posted on 23/5/08 at 09:07 AM |
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Wrong. You're all wrong! The SVA man's never wrong and always right, that's his job you know  (Stands back!)
No I gree really, was just looking for a periodic table to prove it but Kendo's well in there.
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wilkingj
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| posted on 23/5/08 at 09:46 AM |
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What the heck, it should have a rubber sleeve, or insulated type P clip holding the brake pipe on. The galvanic corrosion will take much longer to
puncture the pipe than a steel clip rubbing directly onto the copper pipe. (even if it is done up tightly, it will still vibrate)
Thats a much better reason for the fail.
(ducks and runs for cover)
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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Ketchup
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| posted on 23/5/08 at 12:15 PM |
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mine failed on exactly that at sva! just put some split rubber tube around the pipes and that made them happy
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britishtrident
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| posted on 23/5/08 at 12:16 PM |
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Yes MOT failure point -- Rubber sleeve required to prevent chaffing even on a steel bundy pipe. Chaffing causes fretting corrosion.
Copper brake pipes ---- not great idea anyway -- Kunifer is the stuff to use.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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g.gilo
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| posted on 23/5/08 at 01:59 PM |
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brake pipe clips
hi again
from memory"i am a relic" ford used to fit a small rubber sleave on the bundy tube where required.
graham.
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ReMan
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| posted on 23/5/08 at 05:30 PM |
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quote:
Originally posted by BenB
Being Ford the clip would have rusted away long before galvanic corrosion occured
Or is that, the car would have been stolen long before the clip rusted
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MkIndy7
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| posted on 23/5/08 at 05:35 PM |
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When galvanic corrosion occurs between dissimilar metals it is the most reactive (anodic) metal which corrodes.
Steel is more anodic that copper so it is the steel which will corrode.
Are you sure?
I've seen it where copper hot water pipes have been rested on bare angel iron supports and its pin-holed the pipe.. it did take a long time tho,
probably over 40 years.
Unless it was the movement of the pipe or thermal expansion and contraction making it rub on the bracket, but aparently its not un-common for them to
do this and all new steel brackets have rubber pads in them.
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