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pressure rating for flange 150

According to ASME B16.5 para 2.1 Pressure–temperature ratings are maximum allowable working gage pressures in bar (Psig) units at the temperatures in degrees Celsius (F) shown in Tables 2-1.1 through 2-3.17 for the applicable material and class designation. We can say that the pressure rating (or some time called as pressure class) is the maximum pressure ( MAWP) a piping system should be capable of withstanding at given temperature. The pressure rating related to the temperature of piping system; the higher the process temperature, the less pressure can be handled by the piping system. The detail of pressure rating can be seen in Tables II-2-1.1 through II-2-3.17 of ASME B16.5. For intermediate temperatures, linear interpolation is permitted.

Group of material

Materials for flanges and flanged fittings are listed in Table 1A with the restriction that plate materials shall be used only for blind flanges and reducing flanges without hubs. The most common material is Flange material A 105 for “normal temperature” which is carbon steel material. For high temperature operation, we can use “Cr-Mo alloy” material such as A182 gr F11 or A182 gr F22.

 

what is working pressure?

the working pressure is limited by material group, pressure class and working temperature. For example, a welding neck flange A 105 class 150 can be used up to working pressure of 285 Psig when the service fluid temperature is 100 F. If the service fluid temperature increase up to 400 F, then the working pressure should be limited to 200 Psig. The higher the service fluid temperature, the less pressure can be handled by the pipe, fitting and valve body. Please refer to Table II-2-1.1 for Group 1.1. materials. for piping engineer or pipeline engineer, the most useful table is pressure-temperature rating for Group 1.1 ( carbon steel  ), Group 1.9 ( Cr-Mo-alloy F11 ) and Group 1.10 ( Cr-Mo-Alloy  F22)

 

Class 150 pressure rating for Group 1.1 Materials

Temp C working pressure , bar
−29 to 38 19.6
50 19.2
100 17.7
150 15.8
200 13.8
250 12.1
300 10.2
325 9.3
350 8.4
375 7.4
400 6.5
425 5.5
450 4.6
475 3.7
500 2.8
538 1.4

Class 150 pressure rating for Group 1.9 Materials

Temp C working pressure , bar
−29 to 38 19.8
50 19.5
100 17.7
150 15.8
200 13.8
250 12.1
300 10.2
325 9.3
350 8.4
375 7.4
400 6.5
425 5.5
450 4.6
475 3.7
500 2.8
538 1.4
550
575
600
625
650

Class 150 pressure rating for Group 1.10 Materials

Temp C working pressure , bar
−29 to 38 19.8
50 19.5
100 17.7
150 15.8
200 13.8
250 12.1
300 10.2
325 9.3
350 8.4
375 7.4
400 6.5
425 5.5
450 4.6
475 3.7
500 2.8
538 1.4
550
575
600
625
650

source : Understanding ASME B16.5 / ANSI class 150, 300, 400, 600, 900, 1500 pressure rating – ENGINEERING BLOG (mechanicalengineerblog.com)

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