ASMEB31.3 - Buckling

[KVdA]

Hi all,

Does any one knows why so little guidance is provided by ASMEB31.3 for checking against buckling?
Only §302.3.1(c) seems to provide a maximum being the maximum allowable in compressions not greater than in tension as per appendix A. It is also stated that consideration shall be given to structural stability...
§304.1.3 is only for buckling due to external pressure and refers to ASME VIII div.1 UG-28 through UG-30.
What about combination of external pressure, bending and/or longitudinal compression?
Why is there no reference to ASMEVIII div.1 UG-23?
Can any one think if a reason for this?

 

[XL83NL]

B31.3 sets minimum requirements and is not a cookbook type code. That's why. Remember, "it's up to the designer ... ". Review e.g. 300(c)(3).

 

[DSB123]

xl83nl GIVES THE ANSWER. The B31 Codes are not "Design Guides". They specify minimum requirements and do not fully guarantee that a piping system is fit for service. They provide minimum requirements for safety. It is up to the "Designer" to apply any other considerations he deems necessary to ensure the piping system is fit for service.

 

[KVdA]

OK thanks, and why is there no reference to ASME VIII div.1 UG-23?
How do you all check for a combination of loadings? Any reference to documents/codes which provide guidance.

 

[DekDee]

Why is there no reference to ASMEVIII div.1 UG-23?
Can any one think if a reason for this?

One is a pressure vessel code and one is a pressure piping code ?

 

[David2007]

I think the allowable deflection is indicated in the Piping Stress criteria for each project and then you can analyse the pipe with CAESAR software and make sure to not exceed the maximum deflection. This is also applies to pipe support span for vertical lines.

 

[MJCronin]

KVdA ...

What is the D/t of your piping system in question ?

ASME clearly states limitations on applicability .....

MJCronin
Sr. Process Engineer

 

[KVdA]

MJCronin,
My question was of the philosophical type...
So i don't actually have a D/t ratio.
Are you referring to ASMEB31.3 §K304.1.3?
Chapter IX is for high pressure piping and not always applicable so?

David2007,
I'm not familiar with all possibilities of Caesar, but I don't think Caesar checks buckling. Caesar normally checks against the allowable stresses in tensile and not compression...

DekDee,
Of coarse I'm aware of the fact that ASMEVIII is a vessel code and not a piping code.

The only reason of why ASMEB31.3 is not referring to ASME VIII for axial compression is that the maximum compression is probably over conservative when applying same rules to pipes with a relative small amount of imperfections...

 

[DSB123]

David2007,
The OP was discussing "Buckling" so your response is superfluous since Caesar does not consider buckling. Please only respond with valid responses. It's better to keep quiet rather than say anything!!