Flange Pressure-Temperature Rating (ASME B16.5)
The maximum allowable working pressure of a flange CLASS at a service temperature, read from the ASME B16.5 table with linear interpolation: a Class 150 carbon-steel flange is 285 psig cold but 200 psig at 400 F, and a Class 300 follows its own higher curve (635 psig at 400 F). Bundled ratings are Material Group 1.1 (carbon steel, e.g. A105); other material groups have their own tables. The value is the flange's rating; the weakest component (gasket, bolting, the mating pipe) can still govern the joint. The AHJ and the engineer of record govern.
Formula and source
mawp = interpolate(B16.5 Group 1.1 table[flange_class], temp_f), linear between the table temperatures (100, 200, 300, 400, 500, 600, 650 F). Class 150: 285, 260, 230, 200, 170, 140, 125; Class 300: 740, 680, 655, 635, 605, 570, 550; Class 600: 1480, 1360, 1310, 1265, 1205, 1135, 1100 psig; Class 900, 1500, 2500 scale from the 600 column by 1.5, 2.5, 4.17.
ASME B16.5 Pipe Flanges and Flanged Fittings pressure-temperature ratings, Material Group 1.1 (carbon steel, e.g. A105), by name. The ratings are read from the standard's table with linear interpolation.
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