Shielding gas

Date 03-06-2010 07:17 Edited 03-06-2010 07:21

really it will only apply to the code your welding to...or your engineering standards applied to that job. As long as you fall within those your golden. I think that method will work on all but some ASME standards (guessing from memory)...but other then that from the hip I believe you will shoot ok. As far as AWS C5.10/5 I do not think that will be a blanket for you ....unless the reference is specific on the job callout. Ok time for me to shut up and let the real experts splain it, refute it, or what have you. I am in the way here...but could not help chimimg in.

By Lawrence (*****)

Date 03-06-2010 13:12

Short circuiting transfer for stainless should be a thing in the history books.

There are better ways to join stainless of that thickness.

Traditional spray transfer, GMAWP, or one if the pipes are open root full peneration joints than Lincoln STT, Miller RMD or Feronius CMT would be better choices.

Being a tight-wad with welding gasses is just about the biggest mistake in process control you can make.

Stainless won't shortcircuit well with 98/2, this gas works well for spray transfer.

The helium mixes do best for short circuiting of stainless but your material thickness 3/16 is certainly in the range that can be accopmlished with Spray/Pulsed-Spray or Pulsed/Short-Circuit (STT)

If your welding to a code and you change gasses you will need to run new PQR's anyhow... These will show you exactly the limits of the application :)

Manual welding? Automated welding? What position? Joint design? Square groove or bevel? Root opening? Tell us more J. E.

By Flash Date 04-03-2010 04:42

HI JE
SG-AC-98/2 is fine for your application and is used extensively in Aust. with conventional GMAW
SG-AO-98/1.5 is another common mix
I agree with others that say there is better technology out there to use for your application, but I also come up against plenty of organisations that can not justify the purchase of specialised equipment (even if the ROI warrants it)
your gas will leave the weld slightly dark but should do the job fine
I would be cautious of going vertical down with conventional GMAW on thicknesses above 2 or 3mm
as for your question what are the limited applications - 300 series up to about 6mm thick would be my response
hope this is of some value
Good luck
R
Flash

By j e beckhusen (*)

Date 03-08-2010 04:24

Just a little more to add about the S/G mixture.Most of the vertical & horizontal stright welds are made with a Smart-SPT. Doing a fairly good job but can hold the variables and parameters close compaired to manual. Need CJP, using fiberglass tape ER-0.45 304L and SG-AC-98/2. The problem we are having is trying to get CJP manual welding part. These are the setting we are using, 0.090-0.125 square groove butt root.the same backing tape, The robot welds at a 0 torch angle 0-5 degree travel angle. We are welding from 0-90 degree on both sides then rotating 180 degrees. The reason is all the elbows and transisions are done manually GMAW-S . It seems the bigger the root opening the better. 0.15625-0.1875 is good for me using a STT but still does not short-circuit well ! with SG-AC,98/2. These are large tubes 75-375in. circumfrence but need CJP. I was told we are using the D.1.1., Don,t know how that is that we are not using D.1.6. One more thing it is all V-Down !, using 18-22v-180-220amps. Nobody wants to use the STT,Am I on the right track?

By Lawrence (*****)

Date 03-08-2010 06:34

STT was designed to do just what your doing... Who cares if nobody wants it... Off track,, Drag in your Lincoln rep, he will have those simple joints welded in very little time. He may turn your open roots back to vert-up.

D1.1 is a code for steel... If you are using it you cannot possibly be in compliance... Off track.

If you are running short circuit did you run procedure qualifications..?

If you are running vertical down did you run procedure quaifications?

I don't understand the whole "nobody wants to use STT" part... Who is in charge? Do you have procedures?

This whole thing sounds out of control or at least there appears to be great confusion the more you tell us about it.

By j e beckhusen (*)

Date 03-09-2010 04:59

You hit the nail on the head! We are out of control with no procedures,certs any thing of any kind. I have no one to talk to. I have been at this for 42 years, I have certs = CWI-CWE-ASMT no. of years of collage training. The thing is I like my job! We are a small shop in a small town, (but very high tech.) lazers waterjets ect: except when it comes down to GMAW. Everything we did was GTAW untill a few years ago (95%) Now we are getting in to some very high profile jobs. I really like a challange but don,t know what to do? How about some feed back on welding S/S with FCAW-G, GMAW-S is prequalified welding v-down but you need a min. of 80% he.(7ga max.) Thanks for all your help!

By Lawrence (*****)

Date 03-09-2010 07:02

Gas shielded stainless FCAW is pretty awsome... For fillets and fill passes... I think it would be a can of worms for open root groove welds.

You said:
"GMAW-S is prequalified welding v-down but you need a min. of 80% he.(7ga max.) "

Not if your trying to use D1.1 for stainless :)

By Lawrence (*****)

Date 03-10-2010 19:38

8% C02 for a tri-mix on solid wire GMAW stainless ?

That's a whole bunch of active gas.

Seems a bit high... Not saying it shouldn't be done but its unorthodox to my thinking.

http://www.thefabricator.com/article/consumables/simplifying-shielding-gas-selection

By Metarinka (****)

Date 03-10-2010 23:20

I agree with lawrence. on stainless that's a good amount of carbon to throw into the metal. I htought for this reason co2 was supposed to be limited to under 5% off the top of my head.
Really becomes an issue when you are using low carbon filler such as 316L (as you noted) because you will pick up carbon from the disassociated CO2. good way to cause carbide precipitation.