UG 44 (b) Bolt material maxi allowable stress

[AA Abdullah]

I am designing a pressure vessel and applying loadings on flanges as per UG 44 is raising the issue of "The bolt material shall have an allowable stress equal to or greater than SA-193 B8 Cl. 2 at the specified bolt size and temperature." in COMPRESS, so now I have few questions:

i) Is there a way of eliminating this deficiency without changing the bolt material?
ii) What is the method of choosing an alternative bolt material, what factors will I have to consider?

 

[cbPVme]

i) I don't think you can eliminate the deficiency since it is a code requirement per UG-44(b)(3)
ii) Look in ASME II-D, Table 3 for a bolt material that has a higher allowable than that of SA-193 B8 Cl.2