ASME Seection 8 Div-2 Part 5.

[MDKARMD]

can one one please clarify when to use Part-5 of ASME section 8 div-2??
part 5 can use directly with out doing any check per Part-4??
or if some component fails in part-4 can we check with part-5???
(for example a cylindrical shell fails per part-4 ,can i check it as per part-5???)

Part-5 can be used for fatigue loading,or for non standard cases,or if geometry goes outside the scope etc...
above question is for simple case like cylindrical shell,nozzle reinforcement etc where part -4 is providing the design by rules...
i wanted to use part-5 without doing any thing per part-4...it is allowed or not??

 

[TGS4]

According to the existing rules in ASME Section VIII, Division 2, it is permitted to use the analysis methods and rules in Part 5 to supersede the rules in Part 4. Part 5 may not be used to supersede the rules in Part 3, or Parts 6 through 9. See 4.1.1.5 and 4.1.5.1.

You should note the provisos in 5.1.1 and 5.1.2, particularly 5.1.2.3.

I would consider that approval from the User would be advisable prior to doing this, although it is not a Code requirement. There are also jurisdictions in the world that do nor permit this, so check with the applicable jurisdiction first.

There is (or will be soon) an interpretation advising that it is not permitted to design the shell thickness using Part 5 and then going back to Part 4 for the nozzle reinforcement. Once you're in Part 5, you should perform ALL remaining analyses in Part 5. And, note that (in my opinion) if you design the shell/head thicknesses using Part 5, then you are not using standard details from Part 4, hence the Protection Against Local Failure check would be required to be checked for every component.

For what it's worth, I would not recommend using Part 5 to size shells, heads, nozzles, etc for internal pressure loadings only. The rules are quite good enough.

 

[MDKARMD]

thanks tgs4..