TIG on galvanized?

You can weld it easily without removing the galvanizing, but its going to put off some nasty white smoke that you need to avoid.

Also the finish around the weld will look pretty bad, the heat makes it turn crusty white, somewhat like aluminum corrosion. I guess you can sand it and try painting it silver, but its going to be obvious that it was refinished in the welded areas.

If you're doing a lot of this you better make the customer pay for the right kind of respirator for this, it can be pretty bad for you.

The other way to go is to acid dip the ends before welding. Get some muriatic acid from a hardware store and put a bucket of it out in the middle of an open space outside. This is also nasty stuff so be very careful with it. With a face protector and gloves on, dip the ends in the bucket. They will bubble fiercely for about a minute, when that stops the galvanization is gone and the acid is now working on the steel so take it out. Rinse well in hot water. Avoid the fumes from this operation, they are also nasty. Have a box of baking soda ready to neutralize the acid when you're done. Don't store the acid in your shop, the fumes from it are very corrosive.

Good luck-

Paul T.

Nope.

You need clean, shiny steel to get a decent TIG weld.

Grind off the zinc, or dunk it in muriatic acid then weld it up.

There are "cold galvanizing" paints that you can use to touch up the area.

Or you could weld it up from mild tubing and then have the whole thing hot-dip galvanized if that is available near you. This is far more durable than the thin coating on EMT.

Jeff Dantzler

Your best option is to TIG braze-weld using silicon bronze filler. Keep your heat as low as you can and the bronze will flow right through the zinc with very little burn off.

To TIG weld you would need to remove the zinc from the weld area.

What are you building?

Best practice is to remove 1" coating from all joint ends, inside and outside surface areas. I measure back one inch, tape off coated area to protect, then remove coating evenly with scotch bright preparation disk. Remove tape, weld, clean with preparation disk & wire wheel. Tape protected area again then coat weld area evenly with cold zinc galvanized spray coating.

Clean and prep areas per cold zinc galvanizing spray directions. After all coated areas are dry remove tape. You will have uniform areas around all welds that look clean and evenly coated.

The alternative is hot dipping completed project that can be a lot more costly, require more surface preparation and drilling of drain hole in tubing. Removal of coating from the inside weld areas is recommended. Hot dip galvanizing is charged by finish weight. The coating will cover outside and inside surface areas this adds additional weight and cost to your project.

The trade between cold & hot finish is cost, time, transportation of project, and added weight. Hot dip galvanized coating will be the more durable finish.

Remove zinc, weld, refinish. Several folk have suggested cold galvanizing but, while it works well for protection, I have never seen any that looks quite like the original coating. You can get the neccessary stuff to brush electroplate zinc from Caswell: