corrosion prevention in sheet metal joints

[CalculatorDave]

Hello,

My question concerns the prevention of corrosion in the joints of a sheet metal structure.

Our sheet metal structure is made from pre-galvanized steel sheet, and we join the pieces by clinching. The clinching process is relatively slow (about 1 second per clinch), but has the advantage of not damaging the galvanizing layer. However,we are finding that we need to complete our joints more quickly than is possible with clinching.

Spot welding seems to be the fastest sheet metal joining practice around, but the welding heat vaporizes the zinc coating in the region of the weld. Re-coating these regions(with a cold-galvanzing coating) is not an option.

We are re-designing the structure to reduce the number of joints (thus reducing total joining time), but, still, we´d like something that is faster and that can be automated. Any thoughts?

Thank you, SD

 

[Goahead]

Due to the sacrificial corrosion protection provided by zinc plating it seem you would not need any further protection after spot welding except, possibly, for most extreme cases.

http://www.welding-advisers.com/

 

[mshimko]

What environment is the structure intended for? If atmospheric I would probably agree with goahead above.

However, if it's an occasionally wetted environment, or marine environment, or possible immersed, I would have a different opinion.