GMAW for Structural Members

Date 05-01-2012 18:17 Edited 05-01-2012 19:04

Hello All

The following requirements (A. & D.) are taken from a customer specification for a project I am working on. The project welding spec is AWS D1.1 with the addtional requirements. Our fabrication shop only uses the GMAW process with solid wire, spray transfer on all work including structural. Requirement A. appears to me to be specifying the 4 prequalified processes allowed by D1.1. However requirement D. apperars to be requiring customer approval for GMAW process using solid wire.
Questions:
1. Is requirement A. a poorly written way of saying only the 4 prequalified processes of D1.1 are allowed? Or does it mean, no GMAW with solid wire allowed? Or only FCAW with gas only is allowed?
2. What is the purpose of requirment D. if GMAW is allowed in requirement A.?
3. What do you guys think about using GMAW solid wire spray transfer for use on structural members? I dont see any requirement in D1.1 about this.

A. All welding shall be performed by the manual shielded metal arc, submerge-arc, or gas metal-arc process. A gas metal-arc welding process may be used provided composite (flux-cored) electrodes are used with a shielding gas and operation is performed in the spray transfer range.

D. All applications of solid wire electrodes with a shielding gas are subject to approval by the Purchaser; and in no case will such application be allowed in the fabrication or erection of main structural members.

By welderbrent (*****)

Date 05-01-2012 19:20

I would go straight to the source for some clarification and explain the differences between GMAW (short arc & spray arc) and FCAW (gas shielded & self shielded).

It appears to be poorly written by someone without proper knowledge of the various processes and how they relate to D1.1.

Other than that it would not be wise for us to comment on what EXACTLY they will or will not allow.

Just my two tin pennies worth.

Have a Great Day, Brent

By 99205

Date 05-02-2012 00:54

Pretty much sums it up.

By MBSims

Date 05-02-2012 01:32

I agree with Brent and would interpret the 2 paragraphs as follows:

1. Only SMAW, SAW or FCAW with shielding are permitted.
2. GMAW with solid wire is not permitted unless specifically reviewed and accepted by the Purchaser.

I see no problem with using GMAW spray transfer as long as it really is spray transfer (i.e. droplet size is smaller than the wire diameter, and appropriate shielding gas and current density for spray transfer is used). I see so many vendor procedures submitted for review that are written for "all positions" welding in "spray transfer" mode using 75%Ar25%CO2.

By welderbrent (*****)

Date 05-02-2012 01:38

I did miss one of your questions,

I like GMAW spray arc for many applications on structural welding in the shop. It is smooth, fast, NO clean up, and meets D1.1 just as FCAW or SMAW.

One problem, as AL has pointed out many times, is finding people who can pass a fillet weld test with it. While you can just give them a groove test, that leaves an important flaw in the product. Bottom line is most people can not weld a 1/4" to 5/16" single pass fillet with spray arc and get good penetration.

Also, GMAW spray is limited to flat and horizontal. The highly fluid state does not lend itself to out of position work at all. While most shop structural work is rolled and always down it is not ALWAYS so. There are times you have no choice but to weld vertical or overhead.

Have a Great Day, Brent

By zzzmbrst (*)

Date 05-02-2012 12:42

Thank you all for your replies.

I have now requested a clarification from the customer as to the acceptablility of GMAW.

To Brents comments: I agree with you that spray transfer is only good for flat or horzontal position welding. And sometimes out of position welding is needed. Our only shielding gas is 90% ar 10% co2. I have been pushing for some 80/20 or 82/18 for those situations where out of position welding would be more fitting.