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Post by Deleted on Mar 16, 2015 12:22:24 GMT
Apologies if this is being discussed elsewhere.
The last few weeks on the Vic Line I have noticed paint bubbling just below the window seals on the doors, looking very much like corrosion of the material under the paint. Car 12090 exhibits such signs, one of two I saw in the same day (3 march).
Anyone else noticed?
Presumably these vehicles are still under warranty. Rather alarming for such new trains, and ones that spend most of their time underground...
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Post by John Tuthill on Mar 16, 2015 12:44:35 GMT
Apologies if this is being discussed elsewhere. The last few weeks on the Vic Line I have noticed paint bubbling just below the window seals on the doors, looking very much like corrosion of the material under the paint. Car 12090 exhibits such signs, one of two I saw in the same day (3 march). Anyone else noticed? Presumably these vehicles are still under warranty. Rather alarming for such new trains, and ones that spend most of their time underground... Presumably they go thru' a trainwash? How abrasive are the cleaning agents and the brushes? (Just a thought) |
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Post by Deleted on Mar 16, 2015 18:30:02 GMT
D stock have this, how does Aluminium corrode under the paint?
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Post by Deleted on Mar 16, 2015 19:35:09 GMT
Certainly one train has gone back to Derby for "engineering mods". Whether this includes any corrosion repair work I don't know, nor do I know what the "engineering mods" are. But I am sure the fleet will have go back in turn.
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Post by marri260 on Mar 16, 2015 20:07:13 GMT
I was informed that the reason that they are going back is to recieve the software for 'intelligent sensitive edge', but I could be wrong.
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Post by bigvern on Mar 16, 2015 20:13:45 GMT
Some early trains are at a slightly different build configuration and these are being corrected, with some underframe components being standardised as well.
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Post by John Tuthill on Mar 17, 2015 9:50:39 GMT
D stock have this, how does Aluminium corrode under the paint? Aluminium doesn't corrode, it's a non-ferrous metal. However there will be a 'reaction' chemical or electrical, I can't remember. Ask anybody who has worked on a Land Rover, where you have aluminium body panels bolted to a steel chassis. |
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Post by Deleted on Mar 17, 2015 10:39:11 GMT
D stock were refurbished mid 2000s, and are 35 years old.
09 Stock have just been built. Should they be suffering such issues so soon? OK so they go through a train wash, I would have thought the design spec ensured the trains would be resistant to the effect of washing plants.
Also are the doors aluminium, or some sort of honeycomb/composite? Aluminium/Steel interfaces suffer I believe electrical corrosion. The surface of aluminium forms a tough oxide layer (hence unpainted Aluminium stock turned whitish with age).
Either way, why are blisters showing under the paint of nearly brand new trains...!??
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Post by norbitonflyer on Mar 17, 2015 10:50:41 GMT
Either way, why are blisters showing under the paint of nearly brand new trains...!?? Could it be the paint isn't bonding to the aluminium substrate? |
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Post by orienteer on Mar 19, 2015 15:21:29 GMT
When we restore old buses at the London Bus Museum, we are always careful to apply etch primer to bare aluminium before painting to avoid this.
Let's hope this wasn't skimped on the 09 stock!
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Post by seaeagle on Mar 19, 2015 19:37:14 GMT
Let's hope this wasn't skimped on the 09 stock! Wouldn't surprise me if it was, they were built on the cheap. |
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Post by Deleted on Mar 20, 2015 10:58:04 GMT
Being an engineering apprentice of the 1970's one the first things I was taught about was "dissimilar metals" - Dissimilar metal corrosion is as natural as aging. Simply put, it is an electrochemical process that destroys metal, reducing its thickness and strength. This kind of metal corrosion is also strongly linked to cracking paint; either condition may precipitate the other.
Unfortunately in the modern World of box ticking, reporting, statistics and surveys, basic engineering principles are often not covered and old issues raise their heads again! I remember seeing a near brand new Class 67 showing signs of this type of corresion at Reading and was amazed that basic engineering principles had been ignored.
XF
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Post by Dmitri on Mar 20, 2015 18:51:43 GMT
Aluminium doesn't corrode, it's a non-ferrous metal. The term " corrosion" is not specific to the ferrous metals  . However there will be a 'reaction' chemical or electrical, I can't remember It is called galvanic corrosion. The surface of aluminium forms a tough oxide layer Yes indeed  . Aluminium is in fact pretty active metal. |
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Post by John Tuthill on Mar 20, 2015 20:32:04 GMT
Aluminium doesn't corrode, it's a non-ferrous metal. The term " corrosion" is not specific to the ferrous metals . However there will be a 'reaction' chemical or electrical, I can't remember It is called galvanic corrosion. The surface of aluminium forms a tough oxide layer Yes indeed . Aluminium is in fact pretty active metal. Takes me back to my 'O' level physics!  |
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. Aluminium is in fact pretty active metal.
