When to utilize Caesar's liberal stress allowables?

[jseag]

Hello all- there's a good amount of info on WHAT caesar's liberal stress allowable check box is doing in terms of the calculations. My question to those in the pipe stress industry is WHEN do you use this vs not using this? My company has taken the approach to essentially never utilize the liberal allowables. I'm curious if that is consensus thinking and if not, when you are comfortable using the additional "liberal stress" values? Thank you!

 

[mark howard]

Unchecking the liberal stress allowable (sustained stress margin) as a default procedure creates a simplifying uncertainty factor in your expansion stress analysis. I suggest checking this box (and documenting that you have done so) if there are no other reasonable ways to get passing results; based on your confidence that you have considered all possible operating scenarios, the consequent stress range, the expected life cycle frequency, the potential for creep and ratcheting, and that exceeding yield stress in some locations is acceptable.