OVERHEAD WELDING OF GALVANIZED PIPE TO FLANGE

[quiry13]

I have to weld a new galvanized slip on flange to an existing galvanized pipe. The pipe is vertical. The new flange will slip on from above and be welded around the bottom edge. What would be the best method of repairing the galvanizing?

 

[dik]

If the assembly is 'ordinary', it's a matter of grinding away the zinc from the area to be welded. The zinc produces fumes as well as causing 'spattering'.

Once the weld has been completed and the flux/slag removed (assuming stick), wirebrush the surface and apply a coat of inorganic zinc rich primer. For greater protection, a coat of aluminum polyurethane and a suitable topcoat.

If greater cleaning is required, you might consider a portable sandblaster with 'low dust' grit.

If a more specialized means of protection is required then the system goes up from here. What is the reason for the galvanized piping in the first place?