Chapter VIII discusses the offshore requirements of B31.8. For more information, see B31.8
Calculate the Stress Intensification Factors (SIFs), flexibility factors, and section moduli using B31.8 Chapter VIII
Calculate all SIFs, flexibility factors, and section moduli exactly as in the standard B31.8 Code. Make all stress calculations using the non-corroded wall thickness for the hoop and longitudinal stresses. Use the corroded thickness for the combined stress.
Calculate the expansion load case using B31.8 Chapter VIII
There is no provision for a code check for the expansion load case, so no expansion cases are generated under this code.
Calculate the operating, sustained, or occasional load cases using B31.8 Chapter VIII
Operating, sustained, or occasional load cases are treated identically. For these load cases, you must perform three stress calculations, each with specific allowable limits. The stress calculation causing the highest percent of allowable displays in the stress report along with its specific allowable. The stress checks are:
Hoop Stress: Sh £ F1ST
Longitudinal Stress: |SL| £ 0.8S
Equivalent Stress: Se £ 0.9S
Where:
Sh = (Pi – Pe) D / 2t
Pi = Internal Pressure
Pe = External Pressure
D = Outer Diameter
t = Wall Thickness
F1 = Hoop Stress Design Factor 0.50 or 0.72 see Table A842.22 of B31.8
S = Specified Minimum Yield Strength
T = Temperature Derating Factor see Table 841.116A of B31.8
The product of S and T, the yield stress at operating temperature, is required in
the SH field of the CAESAR II Input:
SL = Maximum Longitudinal Stress Positive Tensile and Negative Compressive
Se = 2[((SL - Sh)/2)2 + Ss2]1/2
Ss = Torsional Stress