Welding galvanized carbon steel
Welding galvanized carbon steel
(OP)
Is there any reason why a mill galvanized carbon steel assembly can not be welded if the steel is to be used in a very cold environment? I know that normally the galvanizing should be removed prior to welding, but what if it is not removed.





RE: Welding galvanized carbon steel
For maximum strength or structural code welds it is advisable to clean the galvanize off prior to welding. It will still require a "cold galvanize". Stay with 6010 welding electrode. Some of the maintenance consumable manufacturers make a special rod (flux) for welding galvanize on non-critical connections.
Any welding on galvanized should be done it the open or well ventilated (exhausted) area and the welder needs a respirator suitable for metal fumes. You will hear people say that's not necessary it is and is required in some areas.
Metal fume poisoning is very pleasant for anyone and especially to some.
Be careful!
RE: Welding galvanized carbon steel
But one confusion "Metal fume poisoning is very pleasant for anyone and especially to some." ??? pleasant ::typo??? or intended ?
Thanks and regards
Sayee Prasad R
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If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!
RE: Welding galvanized carbon steel
Thanks!
The last 2 sentences should read:
Metal fume poisoning is very unpleasant for anyone and especially to some.
Be Careful!
The "some" was a reference to myself and what is now called an industrial hygienist who had argued with me about the hazards of welding galvanize.
RE: Welding galvanized carbon steel
http://www.hdgasa.org.za/welding.htm
There are some galvanizing paints available that take care of the exposed area's, if the rust is an issue.
RE: Welding galvanized carbon steel
Zinc forms brittle intermetallic compound with iron. Cross section some welds on galvanized steel, polish the surface using kerosne as the lubricate and etch with a Cro3 solution. It is not uncommon to find zinc pipes starting at the root of fillet welds.
As one know along the the is aone can observe the HAZ in the steel. There is aloso a HAZ in the galvanizing. Depending on the galvanizing alloy strange intermettalic compound can form (many very brittle) and could cause solid metal embrittlement of the steel. This is time at temperature dependent, therefore watch interpass temperatures, keep as low as possible.
Commercial galvanizing is generally 98% zinc, 2% of aluminum, tin, bismuth, lead, nickel. Several low melting temperature eutectoids can form that could wet the columnar type grain boundaries in the weld's solidifcation zone.
Because of the galvanize coating common low cost NDE methods to locate discontinuities do not exist, with the exception for the limited use AC Dry Yoke magnet particle inspection. ACFM (AC Field Measurement), though realtively new (ASTM standard approved last year)and fairly expensive can detect dicontinuites beneath coating at realtive quick speeds and provide a permanent record.
RE: Welding galvanized carbon steel
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Welding galvanized carbon steel
Concur on the SMAW 6010...the digging action makes it go better but welding galvanized is a messy, foul proposition especially if you use flux core. Wear an appropriate respirator, stay upwind and make especially sure that your protective clothing is adequate. Use leathers if you have them. Sometimes you will get violent eruptions of molten material while welding.
Good luck,
Weldmedic
RE: Welding galvanized carbon steel
Hg
RE: Welding galvanized carbon steel
The crayons have somewhat of a steep learning curve to obtain a good looking finish. Use lots of ammonium chloride flux and a tool and scotch-brite to finish the repair.