Material Is (A53 Gr B) at -20¦F good for -29¦F @ 150 psig.

[LSThill]

Team Members

Ethylene compressor RV discharge that goes into a flare header in the Alcohol plant. Based on the findings from the study, the line in question could reach -29°F @ 150 psig. Our piping specifications(and B31.3), list the temperature limitations for the material (A53 Gr B) at -20°F. I know there are exemptions in B31.3 (see email below), but not sure of exactly how to apply / calculate the stress ratio, and don't really know if they apply in this situation. In addition, I know there are other exemption / exclusions, but not exactly sure how to apply them either.

Referencce to ASME B31.3 INTERPERATIOS 20-15?

L S THILL

 

[eliebl]

The notes to Fig. 323.2.2B define how to apply the stress ratio. In the case of A53 Gr. B the thickness would have to be less than 1/2" or less to be able to use -20F as the baseline. You need a stress ratio of about 0.9 to get a 10 degree F reduction.

EJL