Asme 9 and AWS D1.1: Mixed group welding & equivalent grouping

[ddlmodes]

We used a lot of S355J2, St52.3, & EH36 for main structure. We also used A36 & SS400 for non-critical structure which are welded to the main structure. Out of curiosity, I checked into these two welding codes. Only SA36 & EH36 (AWS D1.1) are 'officially' listed in these code.

1) We have WPS for S355J2 to S355J2. In order to avoid multiple qualification/WPS, how to justify that St52.3 & EH36 belong to the same group 2 in AWS D1.1 (& same P-no:1 Group:2 for ASME9)?

2) We might have WPS for S235 also. Same question arise for the similar grade A36 & SS400. These should be in Group 1 of AWS and P-no:1 Group:1 for ASME9, but how to officially put it into that Group?

3) Finally, both of these steel belong to different strength grade of 220+Mpa to 355+Mpa but will be welded together also.
If we go by AWS D1.1, welding it using the WPS of S235 (weld rod maybe under-match but these are non-critical weld) is allowed?
If we go by ASME 9, we will have to re-qualify a new WPS for this mixed group welding if the previous two WPS do not have the exact same parameters?

For my current application (for subsea but non-primary structure application) the welding code is not that strict, but what is the normal acceptable limit for all these ‘stretching’ to avoid multiple qualification?

In mechanical design point of view, all these are acceptable since the tensile/impact properties are sufficient. Chemical wise, the CEV value is very near also.
In welding code wise, I am quite blur, please enlighten me. Thanks

 

[Kiwi2671]

ddlmodes,
If the materials you intend to weld are not listed in AWS D1.1 Table 3.1 or ASME IX W 422 (eg.JIS SS400) they are classified as an unassigned material and you must have a qualified WPS to support welding of those materials.
Strongly suggest you get someone involved with a knowledge of these two codes to assist you as it is very easy to get bitten on the ass. I will try and find the thread where somewhere had previously completed a major structural project with the same issues you have only to find the client refused to accept due to not complying with AWS D1.1,
Regards,
Kiwi

 

[Kiwi2671]

ddlmodes,

http://www.eng-tips.com/viewthread.cfm?qid=335158

If this does not work as a link go to the AWS section and look for a post on Equivalent Steels on 07/12/12

Hope that helps,
Cheers,
Kiwi

 

[ddlmodes]

Hi Kiwi,

Thanks for the feedback and the massive 600ton example.
So to claim full compliance with the welding code, all these (very similar but) unlisted steel should have its own qualified WPS.

If I rephrase my requirement slightly different:
On the basis of producing safe & strong welding joint but with only 'partial compliance' to the code,
1) Is applying the S355J2 WPS to equivalent steel such as EH36 & St52-3 will still produce safe & strong welding?
2) The same case for the lower strength A36 & SS400 if only one A36 WPS is available
3) Mixing welding for these light weight A36 brackets to the S355 structure using the A36 WPS (design weld strength is sufficient)

With the properties so similar to S355, if we were to weld the St52-3 or EH36 (or mixture) with the same SMAW rods and the same welding parameters as S355 WPS, it should produce the same sound welding also. Correct me if I am wrong?
But without a separately qualified WPS, it will never be able to claim full compliance with the code.

This question arised from my current work with some temporary structures for rig usage. The requirement is strict on the pressure containing (main) part but on the S355 supporting frame, substitute such as St52-3 are always allowed (previously) for ‘secondary beams’ and lower (the main beams are S355 with exact S355 qualified WPS).

BTW, I do not have a welding expert nearby, else I will bombard them with all these questions, haha.
Thanks in advance.

 

[Kiwi2671]

ddlmodes,
You either comply with the code or you don't - there is no such thing as "partial compliance".
If your contract or project specifications require you to be in compliance with a specific code then that is what you must do - if there is no requirement for code compliance on secondary structures or temporary work then you are allowed to basically do what you want.
Be very careful with what you do if you are involved in offshore rig work - something fails offshore and there are no second chances,
Regards,
Kiwi

 

[gtaw]

Partial code compliance is like being partially pregnant.

AWS gives the Owner's Engineer considerable latitude with bending the requirements of the structural welding codes, but you better know what you are getting yourself into when bending those requirements.

Be sure you understand the meaning of the terms “Owner” and “Engineer” before making any hasty moves in the name of saving time or money.

Since the work involves offshore construction, are there government regulations that will not permit the Engineer to override the code requirements?


Best regards - Al