ASME Sec.II 3

[Koros]

what is difference between design stress intensity and maximum allowable design stress in ASME Sec.II, and which one should be selected in refernce temperature for thickness calculation?

 

[TGS4]

What Code are you using to design your vessel? Section I, Section III, Section VIII Division 1, or Section VIII Division 2?

 

[jte]

TGS4-

Why the disrespect for Section XII?

jt

 

[TGS4]

No disrespect intended, I just got tired of typing "Section".

 

[Koros]

ASME Sec. I as design secection but actualy my question is related to two different presnted table data for design stress intensity and maximum allowable design stress in ASME Sec.II

thanks,

 

[TGS4]

Sections I, III Classes 2 and 3, VIII-1, and XII all use Tables 1A and 1B, because those design codes use the Maximum Allowable Stress - S - in all of their calculations.

Section III Classes 1, Tc, and SC all use Tables 2A and 2B, because those design codes use Design Stress Intensity - Sm - in all of their calculations.

Section VIII-2 uses Tables 5A and 5B because that code uses Maximum Allowable Stress - Sm - in all of their calculations.

The above three allowable stresses are all based on different theories of failure and different design margins. API-579/ASME FFS-1 has a good summary of some of these differences in Table B1.4.

Which value (and Table) you use depends on which Code sends you to Section II. The values are not interchangeable.

Does that answer your question?

 

[curtis2004]

TGS4,
What theories of failure behind tables 1A/1B, 2A/2B, and 5A/5B?
Thank you,
curtis2004

 

[Koros]

TGS4,

Thank you for your kind reply,

Koros

 

[TGS4]

1A/1B: Maximum principal stress
2A/2B: Maximum Shear stress
5A/5B: Maximum distortion energy theory

 

[curtis2004]

TGS4,
What theories of failure behind ASME B31-1, and B31-3?
Thank you,
curtis2004