SG2 Vs SG3 wire on weld procedures

[craigthewelder]

I am currently getting prepared for our next 1090 surveillance visit. I have ordered some spools of mig wire and they are SG3, now all our weld procedures were done with SG2 wire, will this be a problem? I would imagine that the heat inputs wouldn't change to much between the two wires, or am i wrong?

 

[Dimitri De Spiegeleer]

What is the denomination according to (BS) EN ISO 14341 of both wires ?
If they are an exact match, then there is no problem.
If not, then your WPQR's (with the SG2) are not valid for the SG3 wire. But I doubt an assessor would fall over such a thing.
If you're only welding steel S235 and/ or S275 but NOT S355, a wpqr is made in a matter of seconds if you use a template for it, and it's completely free.

 

[craigthewelder]

The SG2 is - EN ISO 14341:2008-A-GS3Si1 / AWS A5.18-01:ER70S-6
The SG3 is - EN ISO 14341:2008-A-G42 3 M21 3Si1 / AWS A5.18-01:ER70S-6

On our WPQR it does say SG2 or equivalents, so i'm guessing that would cover us?

 

[Dimitri De Spiegeleer]

EN codes only look at other EN codes, AWS is of no interest here.

But to answer your question: no, 'or equivalent' has no legal grounds, it has to be an exact match.

 

[TechnicAl]

SG3 has higher Mn / Si so its higher strength. In my opinion its different so your SG2 prcedures would be invalid if tensile testing is included.

The SG2 / SG3 designations are basically obsolete (old DIN specs) they are now G3Si1 and G4Si1.........just to confuse everyone I think

The AWS ER70S-6 just about spans both SG2 and SG3 specs in terms of Mn/Si composition limits
Mn limits SG2 1.3-1.6 SG3 1.6-1.9 ER70S6 1.4-1.85......if my memory serves me well.