load case as per ASME B31.8 CH VIII

Dear all Experts Kindly requesting your quick help.

Load cases as per ASME B31.3 Are
Hyd, Sus, Ope, Exp and occ.

Simple listing is
L1 W+T1+P1 (OPE)
L2 W+T1+P1+U1 (OPE)
L3 W+T1+P1-U1 (OPE)
L4 W+T1+P1+U2 (OPE)
L5 W+T1+P1-U2 (OPE)
L6 W+T1+P1+U3 (OPE)
L7 W+T1+P1-U3 (OPE)
L8 W+P1 (SUS)
L9 L1-L8 (EXP)
L10 L2-L1 (OCC)
L11 L3-L1 (OCC)
L12 L4-L1 (OCC)
L13 L5-L1 (OCC)
L14 L6-L1 (OCC)
L15 L7-L1 (OCC)
L16 L8+L10 (OCC)
L17 L8+L11 (OCC)
L18 L8+L12 (OCC)
L19 L8+L13 (OCC)
L20 L8+L14 (OCC)
L21 L8+L15 (OCC)


I am asked to do as per ASME B31.8 VIII
only Ope and SUS
L1 W+T1+P1 (OPE)
L2 W+T1+P1+U1 (OPE)
L3 W+T1+P1-U1 (OPE)
L4 W+T1+P1+U2 (OPE)
L5 W+T1+P1-U2 (OPE)
L6 W+T1+P1+U3 (OPE)
L7 W+T1+P1-U3 (OPE)
L8 W+P1 (SUS)

I am told that as the B31.8 consider allowable directly in relation with specified minimum Yield stress (Hoop,Longi and combined), hence it do not required to model load cases EXp and Occ. and I agree in principle but can anyone please confirm with explanation exact code relation and i am sure to go with it.

pls can some one explain this query?

See ASME B31.8 Chapter VIII Section A842 (Strength Considerations), Para. A842.2.2 (Design Against Yielding)...and Caesar II Quick Reference Guide, "Code Stresses / US Code Stresses".

For Topside Offshore Piping (including Risers), Sustained (SUS) and Operating (OPE = P + W + T and OPE = P + W + T + OCC / Wind, U1 etc.) stresses are to be qualified.

For Longitudinal (SL) stress, the F2 = 0.80 factor is used, while for Combined/Equivalent (SE/Se) stress, the F3 = 0.90 factor is used as per ASME B31.8 Table A842.2.2-1.

B31.8 VIII does not provide displacement stress range evaluation, indeed... and there is no discrimination between Sustained, Operating and Occasional loads - the stress limits are invariant as noted above. If you have only one Calculation Temperature (T1), the second group of load cases is written correctly.

Regards,

Thanks for this response.