Closure Bolting Calculation

[susanta kumar ghadai]

Hii,
in API 16A and 16C closure bolting given,
Bolt tensile stress based on the minimum cross-sectional area of the bolt and stud,shall not exceed the following limit
1)Sa ≤ 0.83Sy
2)Sb ≤ 1.0Sy
Sa = is the maximum allowable tensile membrane stress
Sb = is the maximum allowable tensile membrane plus bending stress
Sy = is the minimum yield strength of bolt material

Question :
1) how to prove equation 2, means how to calculate bending stress ?
i am already calculate equation 1 by referring ASME VIII - DIV.1 (2019) but i did not found any bending stress formula.
please help me out...

 

[GD2]

ASME PCC-1 gives guidance on Assembly Bolt Stress determination. It's usually kept at 40 - 70% of SMYS after assembly.

WRC Bulletin 528 will give you some equations to calculate Bolt stress, otherwise, you have to do a elastic-plastic FEA to analyze the joint.

GDD
Canada

 

[susanta kumar ghadai]

any other suggestion how to calculate bending stress (Sb)?