Dear Stress experts,

I have a query on Sustained Stress Indices

Help content for "SIF Multiplier for Sustained Stress Index" under "SIFs and Stresses" has the following words

"B31.3 Interpretation 6-03 (December 14, 1987) File B31-87-022 permits you to ignore the stress intensification for sustained and occasional loads. To comply with this interpretation (6-03), type 0.0001"

The interpretation from 6-03, File B31-87-022 is as follows:

Question (2): In accordance with ANSI/ASME B31.3, para. 302.3.5(c) and Appendix D, when calculating the longitudinal bending stresses due to sustained loads, does ANSI/ASME B31.3 require that the stress intensification factors from Appendix D be applied?

Reply (2): No. However, see ANSI/ASME B31.3, para. 300(c)(5).

My questions is

Interpretation talks about the consideration of appendix D SIF for SUS and OCC cases, not ignoring the SIF for SUS and OCC. But, CII help shows ignoring SIF for SUS and OCC cases. Is it okay to ignore SIF for SUS and OCC loads?

My understanding about SSI is piping components will have some stress rise in SUS and OCC loads but not high as EXP loads. So codes are stating that SSI can be lower than secondary SIF but not less than 1. Please correct me if I am wrong.


PS: Interpretation attached for reference (Page No:4)