Flange Working Pressure Rating Calculator

Flange ratings are in accordance with ASME B16.5. In this standard, flanges are classified based on their pressure-temperature rating which is also known as a flange class. The pound rating (i.e. 150#) denotes that 150 pounds per square inch is the maximum allowable working pressure of that flange.

Standard flange material is either carbon steel, 304 stainless steel, or 316 stainless steel. This calculator includes chromium-molybdenum alloy flanges which has better weight to strength ratio than steel and is used in high temperature applications. For a full discourse on flange considerations, please check out our in-depth article on flange basics .

To use this calculator input the design temperature and design pressure of the piping system for which a flange must be specified. The corresponding flange pound rating will be highlighted in red for the given temperature and pressure.

Flange Rating Chart
ASTM A105, A350 LF2, A350 LF6 Class 1 Flange RatingMaximum PSI
Temperature (in F°)150#300#400#600#900#1500#2500#
< 1002857409851480222037056170
2002606809051360203533955655
3002306558701310196532705450
4002006358451265190031705280
5001706058051205181030155025
6001405707551135170528404730
6501255507301100165027454575
7001105307101060159026554425
750955056751015152025354230
80080410550825123520553430
8506532042564095515952655
9005023030546069011501915
950351351852754106851145
10002085115170255430715
ASTM A182 Gr. F1 (Chrome Moly) Flange RatingMaximum PSI
Temperature (in F°)150#300#400#600#900#1500#2500#
-20 to 1002656959251390208534705785
2002606809051360203533955660
3002306558701305195532605435
4002006408551280192032005330
5001706208301245186531055180
6001406058051210181530255040
6501255907851175176529404905
7001105707551135170528404730
750955307101065159526604430
800805106751015152525404230
85065485650975146024354060
90050450600900135022453745
9503528037556084514052345
1000201652203304958251370
ANSI/ASME B16.34Maximum PSI
Temperature (in F°)150#300#400#600#900#1500#2500#
-20 to 1002757209601440216036006000
2002306008001200180030005000
3002055407201080162027004500
400190495660995149024854140
500170465620930139523303880
600140435580875131021853640
650125430575860129021503580
700110425565850127521253540
75095415555830124520753460
80080405540805121020153360
85065395530790119019803300
90050390520780116519453240
95035380510765114519103180
10002032043064096516052675
10502031041061592515452570
11002025534551577012852145
1150202002654005959951655
1200201552053104657701285
125020115150225340565945
13002085115170255430715
1350206080125185310515
140020506595145240400
145015354570105170285
15001025355580135230
ANSI/ASME B16.34Maximum PSI
Temperature (in F°)150#300#400#600#900#1500#2500#
-20 to 1002757209601440216036006000
2002356208251240186030955160
3002155607451120168027954660
4001955156851025154025704280
500170480635955143523903980
600140450600900135522553760
650125445590890133022203700
700110430580870130521703620
75095425570855128021353560
80080420565845126521103520
85065420555835125520903480
90050415555830124520753460
95035385515775116019303220
100020350465700105017502915
105020345460685103017202865
11002030540561091515252545
11502023531547571011851970
1200201852453705559251545
1250201451952954407351230
130020115155235350585970
13502095130190290480800
14002075100150225380630
1450206080115175290485
150020405585125205345
(1) Punchlist Zero accepts no liability for damages of any kind, directly or indirectly caused by the use of this calculator.
(2) Ratings are based on standard construction with no heat treatment.