ASME B31.3 - flexibility formal analysis not required (clarifications)

[Fran67]

Hello everybody,

I need clarifications about the chapter 319.4.1 of the ASME B31.3 "formal analysis not required" for piping flexibility analysis.

It is written that the equation 16 can be used if the piping system has no more than 2 points of fixations.
I don't understand this requirement, because a piping system has often more than 2 points of fixation.

If the piping system is composed of more than 2 points of fixation, a flexibility analysis is mandatory?
Or, can I consider that the equation must be checked between each couple of 2 points of fixation all along the piping system (when more than 2 points of fixation)?
Do this requirement cover the case when there is a flanged connection between the two points of fixation?

Thank you
F67

 

[tigny]

Hello,

this part 319.4.1(c) of the code is clearly applicable only to very simple piping with only two points of fixation. Furthermore note 8 states that this method should be used with caution.

In case you have more than 2 points of fixation you can go to still use 319.4.1(a) or 319.4.1(b) before doing a comprehensive piping flexibility analysis.

Note that 319.4.2 Formal analysis does not mandatorily require a comprehensive ASME B31.3 flebility stress analysis. Simplified or approximate method could be used (319.4.2(b))


best regards,

 

[MJCronin]

The responsibility for flexibility analysis and piping system analysis is the business of the piping engineer.

As a reponsible professional, he must answer these questions:

- Which systems require a detailed computer analysis or simplified analysis, and which do not ?

- What type, design and what locations are required for pipe supports ?

- Which piping systems require a more detailed evaluation of nozzle loads on equipment and which do not ?

A piping design specification should be developed for each job. The PDS should specify the type and degree of engineeing required for the specific plant system.

Suggest that you purchase and review the latest edition of the "Piping Handbook" (NAYAAR) for more details on these topics

MJCronin
Sr. Process Engineer