Please allow me one question:

How safe is to use liberal stress when you expect occasional loads?
At first view no link betwen the two, but......

Para. 302.3.5 Limits of Calculated Stresses Due to Sustained
Loads and Displacement Strains

(d) Allowable Displacement Stress Range, SA

When Sh is greater than SL, the difference between
them may be added to the term 0.25Sh in eq. (1a). In
that case, the allowable stress range is calculated by
eq. (1b): SA =f[1.25(Sc + Sh) − SL] (1b)

...and the code allow you to use the extra for secondary stress

Para. 302.3.6 Limits of Calculated Stresses Due to Occasional
Loads


(a) Operation. The sum of the longitudinal stresses,
SL, due to sustained loads, such as pressure and weight,
and of the stresses produced by occasional loads, such
as wind or earthquake, may be as much as 1.33 times
the basic allowable stress given in Appendix A.

....assume that you already decided to use liberal stress.

Any concern?

Do we artificially increase the allowables?

Or is fair to assume that you can use the liberal stress when you do not expect occasional events.

Best regards,

Dan

You can always be more conservative than the code if you aren't comfortable with what it allows.

I would agree with your line of thinking if the stress range S_E occurred during the occasional event. All systems I've worked on take a (relatively) long time to expand and contract, and all my seismic and wind events are (relatively) short duration events.

Thank you.

First sentence: I agree.

Second: for an offshore plant or high seismic activity you might agree?

Best regards,