Section VIII, Div. 2 for Div. 1 Vessel

[LS_SMS]

It recently came to my attention that when Section VIII, Div. 2 rules are used for a Section VIII, Div. 1 vessel via U-2(g), the Div. 1 calculations still need to be performed. Prior to now, I was under the impression that there was no need to do Div. 1 calculations once U-2(g) was invoked and the work scope was moved to Div. 2. So I have two questions...

1. Would someone confirm that my new understanding is correct?
2. Is there ever a case where a Division 2 analysis is performed and Division 1 is not invoked at all? For example, if the end user/owner is specifying a Division 2 vessel, I assume that would mean there's no need to do any Division 1 calcs.

 

[IdanPV]

This is the way I understand it:
If you are applying Div. 2 rules for a Div. 1 vessel under U-2(g), it indicates that "complete details of construction are not provided" and that you should "provide the appropriate details to be used."
It also means that there are no design rules for your case in Div. 1.

• If design rules exist in Div. 1, use those.
• If not, you may reference Appendix 46 and the Div. 2 design rules.

 

[LS_SMS]

This is the way I understand it:
If you are applying Div. 2 rules for a Div. 1 vessel under U-2(g), it indicates that "complete details of construction are not provided" and that you should "provide the appropriate details to be used."
It also means that there are no design rules for your case in Div. 1.

• If design rules exist in Div. 1, use those.
• If not, you may reference Appendix 46 and the Div. 2 design rules.

Rules do not exist in Div. 1 for its service loading conditions. But a source is telling me that Div. 1 calcs would still be performed, only on the design loads though. Does that sound correct?

 

[IdanPV]

Here is an example from my exeprince:
A fatigue assessment is required for a Div. 1 pressure vessel.
The vessel was designed according to Div. 1 rules, considering the relevant design loads. The fatigue assessment was then performed using Div. 2, Part 5, based on its operating conditions.