Piping load classification according to ASME VIII div 2

[fabiper]

Hello all

I’m in charge of the mechanical design of a heat exchanger according to ASME VIII division 2 rules. The seismic analysis is based on ASCE 7 spectrum and earthquake combinations. We also take into account loads from the piping at the nozzles. These loads are produced by thermal restraint of the piping and earthquake (seismic loads due to the piping excitation). These loads are assessed by the piping team.

Pressure loads, loads at nozzles, and earthquake are combined according to ASME VIII division 2, table 5.3.

Since I’m not familiar with ASME rules, my concern here is the classification of the loads at the nozzles due to thermal restraint and piping excitation during earthquake. Should we consider these loads as D, L or E ?

Thank you for your help !

Fabien

 

[XL83NL]

I’m not familiar with ASME rules

I’m in charge of the mechanical design of a heat exchanger according to ASME VIII division 2 rules.

Ask an experienced engineer to do the job for you. You're not qualified for this, obviously.

 

[DSB123]

XL83NL,
Concur with your comments - the two statements are contradictory. You cannot be in charge of the mechanical design if you are not familiar with the required design rules!!!!

fabiper,
Strongly suggest you follow XL83NL's advice and employ/engage a competent experienced engineer to perform the assessment.

 

[fabiper]

XL83NL

Not familiar does not mean not qualified ! Fortunately I know other codes and got stamps. It's quite obvious to contact an experienced engineer when one is looking for information. Now if you don't want to help or don't have an appropriate answer to the question, don't waste your time on this thread.

fabiper

 

[XL83NL]

Qualified in what sense? I have several qualifications and certifications, besides an MSc. in mechanical engineering: this does not per se mean I can (read: should be familiar with the) design (of) pv's, especially those for VIII-2.
On a side note, have you checked if your qualifications and experience meet the requirements of VIII-2?

 

[fegenbush]

DL83NL is correct. The UDS alone for a Section VIII Division 2 vessel is an intense process requiring the skills of a Registered Professional Engineer. If you are not familiar with the code, you are not qualified.

 

[TGS4]

While I agree with XL83NL's assessment, I will provide some comments that address the OP's question in general.

First, it is stresses that are classified, not loads.

Second, the Design Load Parameters as described in Table 5.2 are rather clear. What part of that is unclear to you?

Third, what does the UDS say? And who will be the RPE for the MDR - and what do they say?

The resulting stresses from the Design Load Combinations in Table 5.3 are to be categorized and classified per the rules in the text and as provided by the examples in Table 5.6. Note that when performing the stress analysis, that all FOUR Failure modes must be adequately addressed: plastic collapse (which is handled for an elastic analysis with Table 5.3), local failure, buckling failure, and failure from cyclic (which includes both fatigue and ratcheting). Table 5.3 will only help you with Protection Against Plastic Collapse. Nevertheless, you need to ensure the remaining failure modes are adequately protected against as provided by the rules. Some of the failure modes, such as Ratcheting, require a departure from the typical Design Load Combination approach, and actually require operating load ranges; this requires a bit of a paradigm shift, but once you get it, it will be very clear to you.