CAST IRON FLANGED PIPE FITTINGS WORKING PRESSURES


Cast iron flanged pipe fittings working pressures according to ASME B16.1. Pressure ratings for various temperatures are given for Class 125 and Class 250 flanges fittings. Ratings are independentof the fluid and the maximum nonshock pressures at the given temperatures.


Nonshock Gage Pressure - Temperature Ratings
Temp.(°F) Class 125 Class 250
NPS
1-12
NPS
14-24
NPS
30-48
NPS
1-12
NPS
14-24
NPS
30-48
-20 to 150 200 150 150 500 300 300
200 190 135 115 460  280 250
225 180 130 100 440 270 225
250 175 125 85 415 260 200
275 170 120 65 395 250 175
300 165 110 50 375 240 150
325 155 105 - 355 230 125
353Notes 150 100 - 335 220 100
375 145 - - 315 210 -
406Notes 140 - - 290 200 -
425 130 - - 270 - -
450 125 - - 250 - -

Notes:

  • When used for liquid service, given ratings for class 250 in NPS 14 and larger are applicable to flanges only not fittings
  • Pressure is in lb/sq in gage.
  • NPS - Nominal pipe size
  • The material for flanged fittings are Class B according to ASTM A 126.
  • 353°F (max.) to reflect the temperature of saturated steam at 125 psig.
  • 406°F (max.) to reflect the temperature of saturated steam at 250 psig.

Reference:

  • ASME B16.1-1998, Cast Iron Pipe Flanges and Flanged Fittings - Classes 25, 125, and 250