Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / General Welding Discussion / Mig gas preference
- - By PipeIt (**) Date 03-18-2009 19:36
We use 75 - 25 I am hearing some buzz that 95 -5 is a better choice, lets you run hotter and less spatter.

What do you all think on that one?

A little history he got a bad run of 75-25 one time and ended up with a whole bunch of tear drop leaks on a job.

We had checked everything from wind/drafts and determined the gases were more like 28%  to 29% CO.

We found out by purchasing one of our gas suppliers competitors gases and had them tested. They paid for the repairs and made it right with us, we now receive certified gas.
But I always worry about the guys using up the bottom, that gas is typically bad, we started putting alarms on but they aren't loud enough.

If we do decide to go with 95 - 5 this would me much more preventable in my view?
Parent - - By ctacker (****) Date 03-18-2009 19:54
What does your WPS call for?
Parent - By PipeIt (**) Date 03-18-2009 20:19
WPS gives you a check to pick one or the other.
Parent - - By hogan (****) Date 03-18-2009 19:58
pipeit,
It would help if you could list what material you are going to be welding. 75-25 is fine for short circuiting. Even at 28-29% it should be fine. 98-2 is a better choice if your going to be making cjp welds, and higher deposition rates.
I do have one question what is meant by "But I always worry about the guys using up the bottom, that gas is typically bad, we started putting alarms on but they aren't loud enough."?

Also, what is meant by this line "If we do decide to go with 95 - 5 this would me much more preventable in my view?" ?
Parent - - By PipeIt (**) Date 03-18-2009 20:19
OK I figured this question would be asked, if the bottles get lower then 200# we sometimes get visible porosity, so we don't take chances and usually change them out when they get that low. 

Next if we went with the 95-5 or 98-2 we would not risk the tear drop leaks caused from to much CO2 you are saying your fine at those levels 28% or greater, are you welding pressure pipe or structural? We are welding carbon steel pipe.

it should be fine. 98-2 is a better choice if your going to be making cjp welds, and higher deposition rates.       What does cjp mean?

Thanks Hogan
Parent - - By OBrien (***) Date 03-18-2009 20:53
cjp=complete joint penetration.
Parent - By PipeIt (**) Date 03-19-2009 11:19
Got it Thanks
Parent - - By hogan (****) Date 03-18-2009 21:19
pipeit,
The teardrop defect that you are talking about, it seems like this is a technique issue. Maybe I'm not understanding what is happening. Could you explain in more detail the tear drop leaks you are seeing? Maybe a picture? We frequently weld pipe and structural carbon steel with 98-2.
Parent - By PipeIt (**) Date 03-19-2009 11:18
We haven't had the tear drop problem in years its hard to describe and get a picture of but basically you can have a welded joint that looks like a wedding band and yet you can see these tiny and slow leaks develop from the weld caps, the time it did happen it was traced  back to the higher then 25% CO.
Parent - - By Kix (****) Date 03-19-2009 12:22 Edited 03-19-2009 12:28
Too much Co2???  You can MIG weld fine with pure Co2.  It is actually the gas of choice for most places because it is so cheap and does a really decent job. Your so called tear drop leaks are from operator error my friend.  Sounds like your guys need to work on the setting up of the machine a little bit.
Parent - By PipeIt (**) Date 03-19-2009 15:35 Edited 03-19-2009 15:38
I learn everyday and will never loose sight of that, our welds pass x-ray and I still maintain we had dirty gas, maybe not too much CO2 as you point out.

When we switched bottles the problem went away that's all I can say, that happened about 10 years ago and it was a one time event.

so called tear drop leak I made that up thats what the leaks looked liked they developed slow almost like a bead of sweat.

So called "bead of sweat leaks! : )

The bottom line is I am going to get away from the 75 25 and go towards the higher Argon mixtures.

Thanks!
Parent - - By DaveBoyer (*****) Date 03-19-2009 00:56
You should look at WeldReality.com. This is Ed Craig's website, and He is the shielding gas Guru. By the way, He is not a big fan of 75-25.
Parent - By Milton Gravitt (***) Date 03-19-2009 12:28
  Dave we started using 90% argon and 10% co2 because you can spray arc and short arc with it and far as looks it does a great job.
   

                             M.G.
Parent - - By PipeIt (**) Date 03-19-2009 12:39
Wow expert is an under statement listen to one of Ed's quotes on the subject!

" Mig Gas Fact: "Any global weld shop that uses  the 75% - 25% mix, is  a weld shop without weld management or weld process expertise"

OUCH!
Parent - - By Lawrence (*****) Date 03-19-2009 14:17
Ed may be a bit rough around the edges

But I bet he has the highest batting average in the majors....  The guy is brilliant and makes few mistakes.
Parent - - By bozaktwo1 (***) Date 03-19-2009 17:01
I'm a big fan of Ed's site, and often go there when I need aluminum data before qualifying a procedure.  That guy really knows his stuff.

PipeIt, I use 92-8 in all my steel machines.  It allows a full range of transfer mode, and in spray it's smooth as glass.  I have been here for two years; the company has been using the mix for about 4 years now.  They went through an extensive (and grueling) trial process, and came away liking the 92-8 best.  For what we do here, it is the best choice.  You may need something a little different, depending upon your normal operating values.  If you stay in spray transfer 100% of the time, you need a very high argon content.  Like those before me, I think you definitely want to look at your operators; cleaning, fit-up, manipulation, and machine settings.  Good luck.
Parent - By PipeIt (**) Date 03-19-2009 18:00
Thanks we are trying out some 85 15 and the guys really like it.
Parent - - By hogan (****) Date 03-19-2009 18:30
bozaktwo1,
Good advise. Once you have your base-metal, filler, gas, and amp/volt all set where you want there is typically only one variable left. That is mill scale. When working with GMAW solid wire (spray) the mill scale seems to have more of an impact than anything. There are fillers available that deal with this better than others. But there is nothing better than totally removing it from the weld joint. Time and time again mill scale has caused a process that is running great to go into the toilet. In my shop I have all CJP welds, other than static, that are made with GMAW to be blasted prior to fit up. Maybe it is as little over kill but it has cut down on not only NDT reject but minor discontinuities as well.
Parent - - By Lawrence (*****) Date 03-19-2009 18:32
Progressive quality

I would like to work for you Hogan
Parent - By hogan (****) Date 03-19-2009 18:35
Anytime, I think I would learn a lot from the experience.
Up Topic Welding Industry / General Welding Discussion / Mig gas preference

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill