Does anybody know what is the reason that if you have galvanized pipe, you have to have galvanize free end for welding? Is it a quality of weld or it is cancer gasses that are released while welding?
Both - zinc can adversely affect weld desposit and it will make you sick - forget cancer over the long haul - you will get influenza like symtoms - fever/chills, etc very shortly.
Above is a snippet.
@TheBlacksmith, I think they get the point removal is best, or wear the proper PPE.
From my notes:
-REMOVE ALL GALVANIZING FROM AREAS TO BE WELDED TO PROVIDE 1" MIN BASE METAL AROUND ALL WELDS. WORK SHALL BE DONE IN ACCORD WITH AWS RECOMMENDATION WZC. CLEAN FINISHED WELD AND TOUCH UP WITH TWO COATS OF ZINC RICH PRIMER. PRIMER SHALL OVERLAP EXIST GALVANISING BY 1/2" MIN
Nothing good can come about when welding over HDG. The fumes can make the welder get sick from metal fume fever as some call it. Contrary to what some may say, the effects may go away in about 24-hours, but the sensitivity to the fumes stay with the welder for months if not longer.
Since the thickness of the HDG is not predictable, there is literature that says liquid metal cracking can result if it isn’t removed before welding. Some say zinc can be found in the weld when it is sectioned, polished, etched, and examined.
From my project notes:
WELDING GALVANISED MATERIAL
CONTRACTOR SHALL PROVIDE A WRITTEN WELDING PROCEDURE FOR WELDING GALVANISED MATERIAL WHICH SHALL BE REVIEWED BY THE [OWNER | CONSULTANT | ENGINEER]. PROCEDURE SHALL ADDRESS MITIGATION OF ZINC FUMES FROM WELDING
USE ENOUGH PROPER VENTILATION AND/OR EXHAUST. USE AN APPROVED RESPIRATOR IF SUFFICIENT VENTILATION OR EXHAUST IS UNAVAILABLE
REMOVE GALVANISING FROM WELD AREA BY GRINDING
BURN OFF ALL REMAINING ZINC FROM THE WELD AREA BY TORCH
WORK SHALL BE DONE IN ACCORD WITH AWS RECOMMENDATION WZC
REMOVE ALL GALVANIZING FROM AREAS TO BE WELDED, TOP AND BOT AS REQ’D, TO PROVIDE 1" MIN BASE METAL AROUND ALL WELDS. CLEAN FINISHED WELD AND TOUCH UP WITH TWO COATS OF ZINC RICH PRIMER. PRIMER SHALL OVERLAP EXIST GALVANISING BY 1/2" MIN