Galvanic Corosion

[SRE]

I'm NOT a scientist, I nod off at the first sentence so could someone maybe help me out with galvanic corosion when fitting stainless steel hooks to aluminium rails? Our customer is insisting that we use something like copa slip which is fine in theory but I'm worried about voiding the warranty. Wholesaler not particularly interested, too busy sending out panels to all and sundry, have contacted the manufacturer and am waiting for an answer.

I seem to remember a thread about this ages ago but couldn't find it.

 

[goodwilld]

I thought you only got galvanic corosion when aluminium and mild steel came together?????

 

[oxocube]

You can get galvanic action between any two different metals that are not touching each other but have a current passing between them due to an electrolyte. I have seen a situation where buried bare copper migrated to buried steel pipes, they were buried in desert sand that contains salt which acted as the electrolyte.

I can't see any problem with the ss hooks and aluminium because there is no electrolyte.

 

[BruceB]

You need disimilar metals in contact with each other in an electrolyte for it to be a problem. I have thought about it before, but clearly Schuco do not seem to worried or they would not sell stainless fittings that are designed to contact aluminium rails and brackets. Rain is pretty pure normally (unless it is acid rain!) so to my mind does not really fulfil the criterion of being an electrolyte. However near the sea with salt laden mist/rain would be a different matter. As an example, on an aircraft braking system with stainless bolts on aluminium castings I have used stuff like copaslip recently (and its use is the norm).

Copaslip can only help prevent corrosion. It should not make the quarter turn fitting likely to come undone because those all have a threadlock compound on them. But if you want a definitive manufacturer's view I suggest you ask Schuco.

Regards
Bruce

 

[SRE]

Thanks everyone - there is the potential for salt mist but it's very slight. We use K2 roof kit - still waiting for them to come back to me.

 

[daytona600]

you can get sea mist approved solarworld pv modules in stock if required

 

[Graeme Harrold]

Jointing Compound is the best if you are worried about dissimilar metals. SS to Ally shouldnt cause too may problems as long as you are using good quality SS products.