Thread: Metallurgical Questions

Hello Technical Types,

I asked a couple of metallurgical questions in another thread however it has remained unanswered. It is about what metal/alloy sheeting to place on top of galvanised pipe as a canopy cover. Also what type of rivet and whether to use rubber strip or material type webbing between the pipe and the sheet....

Please click on the link below ...

Fibreglass or Alloy Canopy for Steel-sided Tray back Series III

Kind Regards
Lionel

Lionel
Your not really going to get much galvanic reaction between gal pipe and stainless (either 304 or 316) it's more an academic discussion. I've seen plenty of work benches with this construction, in older food processing facilities, last decades and they are constantly wet. In terms of rivets, stainless or steel will be OK, you should cold gal the steel rivets heads and bottoms after or they will be the first to go. The gal on the pipe will give the rivets some protection though, if you don't. In terms of isolating the connection, once you have established an electrical connection (ie the first rivet) then you've got a galvanic connection, the increase in area isn't really going to increase the galvanic issue (not that you've really got one).
At the joint, any water trapped in the small spaces sets up it's own corrosion environment, keeping the water out of this will be a good thing so the stickaflex as mentioned in the joint will look after this. I would consider ensuring that your joints don't move as the mechanical rubbing off of the gal may be your biggest problem.

Cheers Glen