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Old Peddler
03-03-2012, 08:42 PM
:1eye: Hey Zombie Builders: I have a tip for those of you who are welding EMT conduit. As you know it is coated with zink and zink makes a messey weld. Here is the cure: Before you weld take your flap wheel and sand of the zink coating in the area that you will be welding. You can tell when you get down through the zink, the metal will get shiny. Also unless your body is zink deficient I would suggest that you ware a mask when you grind on the zink. There are pic's below. :builder2:

http://i908.photobucket.com/albums/ac282/lvanyi/Bicycle/100_0158.jpg

http://i908.photobucket.com/albums/ac282/lvanyi/Bicycle/100_0154.jpg

Odd Man Out
03-03-2012, 11:50 PM
Also,
ZINC
fumes can be deadly...

spinner
03-04-2012, 10:14 AM
Hey Zombie Builders: I have a tip for those of you who are welding EMT conduit. As you know it is coated with zink and zink makes a messey weld. Here is the cure: Before you weld take your flap wheel and sand of the zink coating in the area that you will be welding.

Or, you can dip the ends in muriatic acid. The zinc disappears in a puff of smoke/steam. I dip any part that has even a hint of some coating. I use an industrial strength solution and acid safety during handling is very important. Eye and skin protection!!! And avoid the fumes. You would be amazed at how fast the steel turns shiny. Apparently you can use battery acid as well. I haven't.

Hoochie Papa
03-04-2012, 07:37 PM
Inhaling Fumes from welding on zinc will make you sick. To cure this sickness you have to drink milk or drink milk before welding. However the zinc should be removed prior to welding to avoid the zinc fumes.

savarin
03-04-2012, 10:25 PM
I use the acid trick, easier, cleaner and also does the inside of the tube as well.
I wash in plain water then neutralise the acid with bicarb.
Zinc fumes can also kill if you breathe enough of them in but usually its only casting that gets that bad.

tree
03-04-2012, 11:09 PM
With a bit of practice, you can tell the difference between the zinc and steel when grinding by THE COLOR. Also, zinc doesn't spark when grinding, but the steel does. Grind until you see some sparks, then compare the color of the bare steel with the bit that's still zinced.

Or, you could just weld outside or next to a window w/ box fan sucking out...

Or, you could just fill the garage up with white smoke and hope for the best... (I have heard both sides of the coin on the toxicity of zinc fumes - some say "it'll kill ya!!", some say "drink milk, you'll be alright". I think the truth lies somewhere in between - once in a while probably won't hurt you if you have good ventilation, but welding EMT with no prep every day for 20 years is probably going to have some effect.

Taking too much zinc orally can cause you to lose your sense of smell, so it's probably not a good idea to suck the stuff into your lungs on a daily basis. My philosophy is to play it as safe as you're able, but don't be so afraid of it that you can't weld that electroplated washer into a project.

Old Peddler
03-05-2012, 01:12 AM
I use the acid trick, easier, cleaner and also does the inside of the tube as well.
I wash in plain water then neutralise the acid with bicarb.
Zinc fumes can also kill if you breathe enough of them in but usually its only casting that gets that bad.

Savarin; You must be referring to using muriatic acid? Sulfuric doesn't work!

savarin
03-05-2012, 02:13 AM
Savarin; You must be referring to using muriatic acid? Sulfuric doesn't work!

Hydrochloric acid, HCl.

darnthedog
03-05-2012, 11:15 AM
http://www.sperkoengineering.com/html/articles/WeldingGalvanized.pdf

According to this web link it causes what is called Welders flu and last 48 hours of flu like symptoms if Zinc Oxide is inhaled. I was warned during welding class it was a hazard as well. It also says there is no need to grind it off as the zinc completely vaporizes due to low melting point and does not contaminate the weld in any way.

So I don't know what to believe at this point. I am thinking if I ever use it I will just use good sucking ventilation with a blower as well. It will make the welding tougher as I use a shield gas mig. Guess I'll have to go back to flux core to use it.

tree
03-05-2012, 05:48 PM
Welding with flux core creates dramatically more fumes compared to gas MIG, so while you don't have to worry about losing your shielding gas coverage, you'll end up with a higher concentration of gasses to extract too.

I think you could figure out a way to use gas MIG with a fan in the window, without compromising your shielding gas coverage. I've heard of wind baffles being used around the work in areas that are windy. Another option is just to crank the gas flow higher and keep the tip closer to the work.

That being said, flux core and a strong fan will work great too.
Me and my new gas MIG are still honeymooning though, so I have an odd duty to defend her. :P



So I don't know what to believe at this point. I am thinking if I ever use it I will just use good sucking ventilation with a blower as well. It will make the welding tougher as I use a shield gas mig. Guess I'll have to go back to flux core to use it.

Old Peddler
03-05-2012, 06:22 PM
Atomic Zombies; your dead allready, you just don't know it yet!!!!!

Please Let's not get carried away with this issue. I only meant to give you a tip on getting a good weld and in a healthful way. Remember this just clean off the zink and then you will have no worries. You are only involved with it for a small portion of your build so it is not that you are doing this day in and day out. Let's not get in a panic and start taking my tip as a detrimental outbreak of unavoidable plague. Be Cool !!!!!

savarin
03-05-2012, 10:10 PM
The bit about not contaminating the weld I question.
It will depend upon what process you are using.
O/A and stick wont be a problem, the zinc will boil off.
TIG, dont know as I have no experience welding gal with TIG.
Gas Shielded Mig, It spits and bangs and the molten drops fly everywhere. The resulting bead leaves a bit to be desired along with hydrogen bubble inclusions.
If making a full penetration weld the inside bead also leaves a bit to be desired along with heaps of zinc oxides?? (white powdered masses)
I always clean it off as I detest the pops and bangs and resulting skin burns in obscure places.

tree
03-06-2012, 03:44 AM
Gas Shielded Mig, It spits and bangs and the molten drops fly everywhere. The resulting bead leaves a bit to be desired along with hydrogen bubble inclusions.
Didn't know that! I'll have to pay more attention the next time I try it. Done a couple of washers recently with gas, but the last time I did EMT was with flux.

A bit of friendly back-and-forth always comes up when you talk about zinc. :D Same with aluminum frames... *rolls eyes*

I'll cast my vote for grinding it off too!

Actually, I lied - I did this guy with gas, and I remember the text WAS quite a bit easier to do once the zinc was ground off the base plate.
http://tallbike.org/sites/default/files/styles/4-col/public/cthulhu.jpg (http://tallbike.org/sites/default/files/styles/10-col/public/cthulhu.jpg)
http://tallbike.org/sites/default/files/styles/4-col/public/cthulhu2.jpg (http://tallbike.org/sites/default/files/styles/10-col/public/cthulhu2.jpg)
It was just very difficult to control where the pool started without grinding first.

Odd Man Out
03-06-2012, 09:42 AM
A bit of friendly back-and-forth always comes up when you talk about zinc. :D Same with aluminum frames... *rolls eyes*


Rolls Eyes at the "rolls eyes"............:punk::offtopic::punk: