Flange pressure rating variances

[dutch1956]

Are there variances on pressure rating on ANSI flanges.

I.E. 3" diameter std 150 class line,,,,C/S
<100F,,,,,,,285psi
PSV set at 295psi
Acceptable or not???

 

[metengr]

No. The pressure-temperature ratings unique to flanges as referenced in ASME B16.5 is the maximum working pressure for the stated service temperature. So, for a standard 150 lb class flange made from carbon steel, the maximum allowable working pressure at 100 deg F or less fluid temperature is 285 psig.