ER70S-4 to ER70S-6

Date 10-13-2011 13:24

I think not. (Was your original procedure impact tested but you just want to change the root pass from a non-impacted tested ER70S-4 consumable to ER70S-6 with impact properties?)

By 803056

Date 10-13-2011 15:18

Assuming you are fabricating materials in accordance with ASME, switching from ER70S-4 to ER70S-6 does not involve a change in F number or A number. Both are listed in the same FM specificication, e.g., AWS/ASME A5.18. Therefore the change can be made with an editorial revision per ASME Section IX. However, you need to check the specific construction code, i.e., Section VIII or B31.3, etc., to verify whether additional restrictions have been invoked and check your contract with your customer, they may need to be notified of any changes to the WPS.

Best regards - Al

By nantong (**)

Date 10-13-2011 15:48

Does ASME IX 404.12 not come into play as a supplementary essential variable?

QW-404.12

A change in the filler metal classification within an SFA specification.......

By 803056

Date 10-13-2011 16:43

The supplementary variables only apply when impact toughness is a requirement. This post specifically said impact toughness was not an issue.

Best regards - Al

By nantong (**)

Date 10-13-2011 17:20

Sorry Al but what I see for the original post is that it does.

By 803056

Date 10-13-2011 17:59

You are so right!

A case of reading what you think it says rather than what it actually says. Thank you for finding my mistake.

Open mouth, insert foot! Swallow hard, there goes my self esteem!

Natong is correct, a change in electrode classification is a S.E., so the revised WPS would have to be requalified.

As I've said before, my advice or opinion is only worth what you pay for it. In this case it didn't cost anything and it wasn't worth anything. :red:

By nantong (**)

Date 10-13-2011 18:14

Al, but think about what I said in my first response, is it so critical for the root pass which will not be substantially sampled in a charpy specimen? Technical basis or work ethics?

By 803056

Date 10-14-2011 01:35 Edited 10-14-2011 01:50

All things being equal, the root pass will most likely be welded with the fastest cooling rate; hence it will have a finer grain structure than any of the subsequent weld beads that follow. Since fine grains typically produce the better toughness when compared to slower cooled coarse grains, the toughness of the root pass should be better than the remaining weld (if the books I read have it correct). That being the case, if the Charpy test pieces are taken from the intermediate layers and is found to be acceptable, the root beads should be acceptable as well.

The realities of life paint a different picture. If the welding process is either manual or semi-automatic, the welder is going to vary the travel speed, thus heat input, from one pass to another. Even if the welding parameters are limited to those ranges permitted by the code, there is always some question of whether the toughness of the production weld is really represented by the test weld. Toughness testing is just one of several tools used by the engineer to select the welding parameters that will produce acceptable welds in a consistent manner. This is only true if the welders understand the importance of working within the ranges permitted by the WPS.

As you note, the ER70S-4 is not required to meet notch toughness, but clearly has some acceptable values if it was qualified with impact toughness testing. We are not informed of the actual test values for the ER70S-4. However, just because the ER70S-6 does meet certain toughness requirements (per AWS ASME A5.18) is no guarantee it will meet those same values if heat input is not controlled.

Best regards - Al

By Firefly (*)

Date 10-14-2011 11:07

Thanks for the replies thus far. The original WPS qualified with ER70S-4 was qualified with impact testing and complied. As you have mentioned ER70S-4 does not require impact testing where ER70S-6 does. That's reasoning behind wanting to change the consumable. Comman sense tells me it should be fine to "upgrade" from ER70S-4 to ER70S-6 but I cannot find a clearcut answer in ASME IX. I can understand that "downgrading" from ER70S-6 to ER70S-4 would be frowned upon though.

PS We are working to API 6A which refers back to ASME IX.

Rgds

By js55

Date 10-17-2011 12:07

Going from 4 to 6 is not necessarily an upgrade. Its a change in filler classification. The definition of upgrade is depended upon what the intended service is.
Also, be careful of S-6. Its Mn range falls outside A1 chemistry and so you need to verify you comply with an A1 chemistry as determined by your procedure. Heat control and actuals on MTR's will do it.