Reinforcement Area on Shell

[c8829]

Hello Everyone.

Top dish opening has reinforcement area falling on shell, is it acceptable or does code says anything about it???
Does the radiography of top dish to shell comes in to picture???
Thanks.

 

[SnTMan]

c8829, Please state your Code of construction, and maybe supply a sketch.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[c8829]

Construction Code is ASME SEC. VIII DIV 1.
Attach file shows that nozzle reinforcement area falling on shell also.

Thanks.

 

[nickelkid]

I am having difficulty seeing this design being within Div. 1 and look forward to seeing comments from others...

 

[TGS4]

Such an arrangement is not covered by the rules in VIII-1 - especially the nozzles in the knuckle of the head. See U-2(g).

 

[SnTMan]

Agreed. c8829, you are on your own

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[c8829]

Thank TGS4 but with all Respect please have a look attached interpretation.

 

[nickelkid]

c8829, it appears you have the answer. Thank you for posting the interpretation.

 

[SnTMan]

Well, good to know, thanks c8829

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[TGS4]

If you are constructing to the 2001 Edition with 2002 Addenda, then you have your answer. I would be hard-pressed to reconcile your drawing with that interpretation (not to mention that I disagree with that interpretation).

Nevertheless, the decision is not mine - check with your AI and/or the jurisdiction where your vessel will be located. They have the final call.

 

[nickelkid]

I believe TGS4 has a valid concern. It appears to me that the interpretation can easily be misused to facilitate arguably poor designs. In general I am slow to digest these types of things, but would be hard pressed to move forward with this type of design without some FEA to back it up as a minimum.

 

[r6155]

I will never do this design.
Regards
r6155

 

[nickelkid]

I do lean towards the position of r6155...

 

[GenB]

It seems to me that is a Code accepted design. Its clear the Interpretation is there. The interpretation is only to make a paragraph clear unlike a CodeCase that can be rejected by a binding Jurisdiccion.

 

[TGS4]

GenB - I agree that the interpretation appears to be clear. Nevertheless...

APPLICABILITY OF INTERPRETATIONS
Each interpretation applies to the edition and addenda or supplement listed for that inquiry including prior and previous editions where the requirement is identical. Many of the requirements on which the interpretations have been made are revised in later editions, addenda or supplements. Where such revisions have been made, the interpretations may no longer be applicable to the revised requirement. ASME procedures provide for reconsideration of these interpretations when or if additional information is available which might affect any interpretation. Further, persons aggrieved by any interpretation may appeal to the cognizant ASME committee or subcommittee. ASME does not "approve", "certify", "rate" or "endorse" any item, construction, proprietary device, or activity

Considering the subsequent changes to Appendix 1 and the new rules in Division 2, I'm not sure that I would read too much into that interpretation.

 

[MrPDes]

When calculating the reinforcement contribution from the cylinder, make sure you don't use the minimum thickness of the head. You have to use the minimum thickness of the cylinder.

In terms of buckling, a nozzle in the knuckle region acts as a stiffener and actually improves the stability of the knuckle region.

In terms of plastic failure, the reinforcement calculation uses minimum buckling thickness rather than the much smaller minimum pressure thickness of the knuckle. As a result the local membrane stresses in the head and the crotch corner stress will be very conservative.

I think the interpretation exists because ASME VIII-1 head knuckle regions are so chunky compared to other codes.

As TGS4 says, I definitely wouldn't use it with parts of the code that have been revised since the interpretation was published.