Differences in time dependent properties temperature for SA-387 Gr 11 Cl 2 in Table 5A of Sec II D

[VeeEng]

Hi All,

As per Table 5A of ASME Sec II part D (customary), for SA-387 Gr 11 Cl 2, note T5 states that "Allowable stresses for 850F and above are obtained from time dependent properties", Whereas per Table 5A of Sec II Part D (Metric), note T7 states that "Allowable stresses for 500C and above are obtained from time dependent properties". I understand that either one of the units to be followed and we are not supposed to convert values, but the difference seems to be significant. (almost 80F) . There is some minor deviation for SA-213 T11 too. I might be missing something here. Anyone could help with the reason behind it ?

Thank You
VeeEng

 

[IdanPV]

Hello,

This happening alot when values are shown in SI or U.S. Customary units, there is a deviatin.

Per VIII-1, U-4(b) "A single system of units shall be used for all aspects of design"
You can't mix system of units.

See VIII-1, Nonmandatory Appendix GG for more information.