low temp piping operating stress in stress ratio calc

For low temperature piping in ASME B 31.3:2004 Fig-2223.2.2B note a 3,Is the combined longitudinal stress(without SIF) the operating loadcase stress - used in computing stress ratio to have temperature reduction from the limiting temperature for the piping material & thickness combination to avoid impact test?

regards,

sam

Note (b) Says -----" Loadings coincident with the metal temperature under consideration shall be used in determining the Stress Ratio as
defined above."

Regards
Siv

Dear Siv,

In note a(3)of Fig-2223.2.2B, longitudinal stress due to pressure,dead weight & displacement strain is mentioned. This 'displacement strain' indicates that this stress computed is operating stress.

By refering to note b, are you saying the same is right ?

regards,

sam

Sam,

You are correct its operating stress. But include F/A stresses and exclude SIF for your operating case. Also be aware, column B of table 323.2.2 has to satisified to further proceed to stress ratio.

For ex if pipe is CS and design temp is less than -20, then B-3 of table 323.2.2 has to be taken into consideration before you can proceed to calculate stress ratio. ie further, it requires to meet note 2,3 and 5 for table 323.2.2.

Thanks
reub