copper degradation/corrosion

[Major Phucup]

can anybody help with the problem of copper corrosion of an ac unit in a high voltage switch room in a sugar refinery.

[Tesla]

The high voltage switch gear would induce / radiate current and voltage to steel / copper on ac unit, this could accelerate corrosion. The heat transfer areas could be filtered to minimise corrosive elements, other exposed metal should be well grounded (earthed) and /or insulated from atmosphere. More info would be helpfull - photo, areas...

[Major Phucup]

i've heard that it may have something to do with ozone? i haven't been to the site yet, but from the engineer who has he's likened it to what you see on the inside when you braze without nitrogen but on the out side of the copper? will get some pics if i can

[Peter_1]

If there's ammonia ion the air, then I've seen it many times (slaughtery, fish shops, ...)

[jinxycat]

here are some pic's of the copper pipe work, it has done the same to some old copper bus bars, and a redundent halon line, also the brass crimps have gone black, not quite corrosion but almost a plating, on the areas that would have had a bit of a sweat it has gone quite powdery/flakey, but on say the discharge line it is like the inside of a non nitro braze, it is leaking on six seperate welds, could it be the ozone oxydising at an accerated rate, there is also almost a sulphur smell to the room but nothing around that contains any sulphur bases

[Peter_1]

Major Phucup and Jinxycat, what's the relation?
There must be something in the air that oxidizes with your copper.
Here in Belgium, I should take some samples and send it to the university of Gent hear nearby. They have a special lab for corrosion with an electron microscope.

But then, if they find the source of your problem, it's up to you to find a solution for it and this can be not that easy.

[Rhew]

I last time i saw that colour on copper was at a brikworks above the kilns it was on a split the condensing unit was ok but the evap had lost all of its fins with just the pipes left and at that same dark colour, they reconed it was the sulpher in the air but it had eaten the fins in about 18 mts, no help to your problem just an observation but will be interested to know what you come up with as to the cause.

[kiwireeferman]

I think your only solution will be to paint all pipe-work and silversolder all joints. I have seen a similar problem on a ship that had a sewage treatment plant in the same area as refrigeration units.
I spray painted all pipe-work with poly eurethane.

[jinxycat]

thanks for all your thoughts on this subject and i will up date as i get any info, we fitted a new unit a couple of weeks ago and yes we "kirby coated" the whole thing prior to the install (kirby coat is a spray on epoxy treatment) and yes we are in the process of getting both copper samples and air samples anaylised, its good to know we are on the same page though

[jinxycat]

Major Phucup and Jinxycat, what's the relation?
There must be something in the air that oxidizes with your copper.
Here in Belgium, I should take some samples and send it to the university of Gent hear nearby. They have a special lab for corrosion with an electron microscope.

But then, if they find the source of your problem, it's up to you to find a solution for it and this can be not that easy.

yes you guessed its the same job, lol. its either oxydisation or sulphation

[Major Phucup]

Nice pic's with the phone mate.

[The MG Pony]

Nice pic's with the phone mate

All the sheep escaped!

[stefs_cruiser]

I have seen black copper like that, and in my experience it is something like methanol in the air.
The coppor won't leak, but it will be the silver joints going porous.

Iether use a better typer of silver, ie higher silver content or implement a physical barrier like a coating of sorts...

[fooboy]

We do a bit of work in Rotorua which the atmos is really sulphurous (is that a real word?). If it's any help we spray all coils and exposed copper with Dinitrol

[jinxycat]

hey all, many thanks for your thoughts on this subject, we got the results of the pipework back today, and the winner is.................drum roll.............sulphur, not just a bit, but like off the scale amounts, so back to the people at the plant who swear blind there isnt anything sulphur or containing sulphur compounds, and as for you the mg pony do you want some canadian jokes eh? lol