Trying to weld galvanized steel tubing

Date 10-30-2008 06:29

Hello Orlando, there are a number of different ways you can approach this. One of the better ways is to remove the galvanized coating before trying to weld on it. If you do this you will still want to have plenty of ventilation while you are welding as you won't be able to remove the internal coating on the tubing and it will still burn and smoke a bunch. If you decide not to remove the galvanizing and still wish to weld it, I would suggest using the self-shielded flux-cored wire that can be run on your machine, probably the .030 diameter stuff. Here again be sure to use plenty of ventilation as well as some form of a respirator if at all possible.
If you decide to grind the coating I would suggest spraying some WD40 on the grinding wheel to keep it from loading up with the zinc coating while you are grinding. You could use the solid wire with a shielding gas if you decide to remove the zinc coating, but if you leave it on you may see the non-sticking issue that you are talking about, this is due to the zinc and other components of the coating interfering with the weldability of the metal. Hope this has possibly answered some of the questions that you have on this. Best regards, aevald

By tazmannusa (**)

Date 10-30-2008 15:08

Not sure if your 110 will do it but usualy crank up the volts a bit and weld slow with a bit of weave to burn through the galvanizing, nasty stuff
Tom

By hogan

Date 10-30-2008 15:26

Please don't follow taxmannusa's recommendation. You will have poor quality welds and the fumes will be hazardous to your health.

By tazmannusa (**)

Date 10-30-2008 23:49

Is it a taboo to weld galvanized now days? My preferd menthod is 6011 stick or (1109) to some. it can and is done with mig flux or solid.
If you cant weld through galvanizing and make a good weld then I would not recomend getting a welding job in dairy construction.
Tom

By Jeffrey Grady (***)

Date 10-30-2008 15:38

ORLANDO,
Please listen to aevald and hogan on this. Grind that galv. off! If you grind it off you will see that it will be possible to weld the tubing with your machine. You will also save yourself some respiratory damage, and a world of headache from trying to burn through that galv. Just My opinion on the matter.
Jeffrey

By swnorris (****)

Date 10-30-2008 16:26

Also, there's issues with weld porosity and cracks in the welds if the galvanized coating is not removed prior to welding. And, if the galvanized coating is not uniform, cracking may occur to a varying degree associated with the varying coating thickness.

By cnd_weldeng Date 10-30-2008 17:21

The self shielding fluxcored wire will usually solve your problem with the porosity issue when welding galvanized coated steel. The reason being is the zinc in the galvanized coating will begin to boil at the point the the steel become "molten", thus the out gasing of the zinc will cause your porosity. Even though many people weld galvanized coated steels with solid wire, throw it under an xray and you will most likely see subsurface porosity.

Just my two cents, the above posts really hit your question home!

By Lawrence (*****)

Date 10-30-2008 17:48

True enough.

Self shielded FCAW (remember DCEN) is the best way to run when welding things that have been galvanized with a 110 unit.

Even when you remove the coating (which is still recommended with FCAW) there is almost always residue and the FCAW is a better option.

If you insist on solid wire.
ER70S-6 tends to crack when welding things that have been zinc plated

ER70S-3 is a better solid wire choice

By sickytwisted (*)

Date 10-30-2008 19:28

You guys are awesome. I'm a rookie welder. THANKS

By MDG Custom Weld (***)

Date 10-30-2008 19:44

You guys beat me to it. I read this earlier but did not have time to respond, but I planned on stating that FCAW would be the way to go (other than removing the coating).

By sickytwisted (*)

Date 10-30-2008 21:54

What is DCEN? You can also tell me what DCEP is. I looked it up and found the two terms but no deffinitions.

By mountainman (***)

Date 10-30-2008 21:58

direct current electrode negative.......direct current electrode positive.

By aevald

Date 10-30-2008 23:23

Hello Orlando, mountainman gave you the definitions for those acronyms. If you don't quite understand here is a slightly expanded definition. The DCEP(direct current electrode positive) means that your welding gun is attached to the +(positive) terminal and your ground is attached to the -(negative) terminal. In the case of DCEN(direct current electrode negative) the welding gun is attached to the -(negative) terminal and the ground is attached to the +(positive) terminal of the welding machine. When you open the side cover of the machine where the wire spool is located you will probably see a couple of terminals with wingnuts on them that attach the cable that leads to the feeder mechanism and the other cable will go through the front of the case and attach to the ground clamp. By switching these you will be able to set the machine to the correct polarity.
If you are using the self-shielded wire you will need to be sure that the machine is set-up for DCEN. If you are using the solid wire with a shielding gas the machine needs to be set up for DCEP. Hope this explains it more specifically and I only included these additional instructions in case you weren't quite familiar with this. Best regards and best of luck on your project. aevald

By jwright650 (*****)

Date 10-30-2008 23:35

Good post guys. A simple mistake is to forget to switch the polarity when switching from FCAW(cored wire) to GMAW (solid wire) or visa versa. Well covered.

By sickytwisted (*)

Date 10-31-2008 06:44

Muchas Gracias