Material Group Number

Date 06-25-2012 18:50

Hello all, I need some assistance on group numbers.

If a group number on a WPS says group 1 to group 1, that means the material located under group 1 can be joined to other group 1 materials. What if A 36 material that is less than 3/4 in thick is welded to material more than 3/4 in thick, then should the WPS read group 1 to group 2? I believe the anwser is yes. I guess what I'm trying to get to is, how should it be worded on a WPS if A 36 material less than 3/4 in. is welded to material that is more than 3/4 in. and then for the same WPS to able to weld group 1 to group 1 and group 2 to group 2 and group 1 to group 2 and vice versa in case af varying thicknesses or same thicknesses.

How would it read on the WPS?

Group 1 to Group 2
Group 1 & 2 to Group 1 & 2

?????

Thanks,

By OBEWAN

Date 06-25-2012 18:58

First of all, what code are you welding to?

And, if I am not mistaken, my experience has been that group numbers are for material chemistry and not size.

By jwright650 (*****)

Date 06-25-2012 19:10

Sounds like D1.1 when someone is referring to A36 and quotes the thickness breaks from Table 3.1.

By jshot

Date 06-25-2012 19:20

Yes jwright, you're correct, D1.1 and table 3.1.

By 803056

Date 06-25-2012 21:08

The thickness limitations come into play with D1.1 and ASTM A-36 due to the need to use low hydrogen electrodes when welding the thicker material (>3/4 inch). The prequalified WPS must have a means of indicating when low hydrogen electrodes must be used or limit the welding to low hydrogen electrodes when using SMAW.

Best regard - Al

By TimGary (****)

Date 06-26-2012 11:05

AWS D1.1 : 2010 separates common carbon steel base metals in groups based on their weldability (matching filler metal and pre-post heat treat requirements).
Table 3.1 lists Prequalified Base Metal - Filler Metal Combinations for Matching Strength (see 3.3).
Table 4.8 lists WPS Base Metal Group Combinations Allowed by PQR (see 4.8.3).
A36 equal to or lkess than 3/4" is listed as Group I.
A36 greater than 3/4" is listed as Group II.
If your PQR is performed on A36 3/4" or below, the WPS can be used on that material grade and thickness or for any other listed group I base metal.
If your PQR is performed on A36 above 3/4", the WPS can be used on any listed Group I or II base metal or combination thereof.

There's more to it than just that, but it's a good start to look where to research the code requirements.

Tim

By jwright650 (*****)

Date 06-26-2012 12:34

If you're using all low hydrogen electrodes....just spell out the electrodes being used and you can weld Group I and Group II combinations on the same WPS.

By jshot

Date 06-27-2012 01:37

Hi jwright, it's GMAW.

By 803056

Date 06-28-2012 03:42

GMAW is considered to be a low hydrogen process. As such, you should have no problems welding any base metal listed in Groups I or II.

Al

By jwright650 (*****)

Date 06-28-2012 11:24

Thanks for adding the additional comments AL...I meant to post back, but got caught up in the rush of inspecting lots of pieces headed for the truck leaving this morning.