Welding and Galvanization

Answer NO.. Remove galvenised layer where weld is to go.

hi,

thanks for reply,can you please give me any reference specification.

with regards.

Agreed...no!....now for why (from personal experience):

As you weld, you melt the base metal and add filler right? What happens to that zinc coating? It doesn't all burn off. Most actually is melted along with the base metal and then alloys with it changing the properties local to the weld. In most cases creating a weak boundary at the weld-base metal interface.

The zinc coating that actually does burn off creates highly toxic fumes, that you REALLY don't need to be breathing.

hi,

how can i remove galvanising coating,

with regards

An angle grinder works for me!

Remove by grinding, deburring tool, file or machining.

If you breathe the gases of the burning zinc (even surrounding zinc after removal) you will feel quite ill. If this happens, drink about a liter of milk. I've found it's the only thing that helps a bit.

'If this happens, drink about a liter of milk. I've found it's the only thing that helps a bit.'

This is the 'old school' way of doing things, has anyone got a good medical explanation for this, or is it an urban myth!

Sorry to be 'old school' PlbMak, but it's still a good school. Take a quick look at home treatment on

http://www.nlm.nih.gov/medlineplus/ency/article/002570.htm

I'm not knocking 'old school' at all, I was just wondering if the treatment was genuine, or something like an urban myth. The link backs up the treatment, but still, I'd like to know why?

Yes, You can do welding on galvanised areas as long as it is in open. There will not be much of a health problem. If required use portable exhaust fans.

If required , use cup wire brushe with 4" AG-4 (or) stringer brush with GQ-4 grinding machines ( available at all Industral hardware stores in India) for cleaning.

Use E 6010, E 6013 for SMAW or ER 70S-6 for MAG/Co2 welding Processes. Paint it back ( zinc) after welding. We have done lot of pipes with good results and still ( more than 12 months ) in use .

sridhar

The zinc coating is vaporized if you breathe it in the zinc gets into your bloodstream. You get enough of it in your lungs your lungs can react adversely depending on your sensitivity to the zinc and other by products. Basically it can kill you. I used to arc weld and had a ton of zinc coated scrap metal available. I would hold my breath during the weld and flip my hood up walking away and then breathing. Then chip the slag and put another stick in the handle and start again holding my breath at first arc. Did that safely for years.

Safety got on my case and told me I had to wear a respirator. They gave me the respirator set up with an organic filter. The safety guy didn't understand the differences in filters and set me up with a nearly fatal accident. With an organic filter on it, the mask worked great on the smelly fumes but did not stop the zinc metal gases. I couldn't taste it as I breathed it in. Before long I ended up in the emergency room. Zinc metal in the body has a half life. It takes a very long time for the body to rid the metal from your system. It effects the nerves some. The only real cure is time.

Use HCL acid to clean the zinc out of the base metal. That will solve the problem of toxic fumes ( deburring and other processes will leave some residue but HCL will not leave any)

Naveen

Indianapolis

its ok what about hydrogen in HCL .Heared adout metel embrittlement Can HCl be the reason for embrittlement.

Not clear Pl clearify

"Can HCl be the reason for embrittlement."

In the short amount of time HCl will be in contact with the metal, hydrogen embrittlement should not be a problem. Just rinse well.

As to the gasses produced, most modern galvanized coatings contain cadmium. Cd vapors are much worse than Zn.

Bill Morrow