Pressure-Temperature Ratings for ASTM A350 LF2 Flanges

Pipe flanges made from ASTM A350 Gr. LF2 steel are usually manufactured in accordance with ASME B16.5 or ASME B16.47. It is a typical Group 1.1 material. The pressure-temperature ratings for ASTM A350 LF2 indicate maximum allowable working pressures in bar or psi units at the temperatures in °C or °F units. For intermediate temperatures, the values can be obtained by linear interpolation (Flanges conforming to ASME B16.5 covers Classes 150, 300, 400, 600, 900, 1500 and 2500; Flanges conforming to ASME B16.47 covers Classes 75, 150, 300, 400, 600, and 900).

Temp. °C	Working Pressures by Classes, bar
	75#	150#	300#	400#
−29~38	9.8	19.6	51.1	68.1
50	9.6	19.2	50.1	66.8
100	8.8	17.7	46.6	62.1
150	7.9	15.8	45.1	60.1
200	6.9	13.8	43.8	58.4
250	6.0	12.1	41.9	55.9
300	5.1	10.2	39.8	53.1
325	4.6	9.3	38.7	51.6
350	3.1	8.4	37.6	50.1
375	-	7.4	36.4	48.5
400	-	6.5	34.7	46.3
425	-	5.5	28.8	38.4
450	-	4.6	23.0	30.7
475	-	3.7	17.4	23.2
500	-	2.8	11.8	15.7
538	-	1.4	5.9	7.9

*Table A: pressure-temperature ratings for ASTM A350 LF2 flanges; Class 75, 150, 300, 400; Working pressure: bar; Temperature: °C.

Temp. °C	Working Pressures by Classes, bar
	600#	900#	1500#	2500#
-29~38	102.1	153.2	255.3	425.5
50	100.2	150.4	250.6	417.7
100	93.2	139.8	233.0	388.3
150	90.2	135.2	225.4	375.6
200	87.6	131.4	219.0	365.0
250	83.9	125.8	209.7	349.5
300	79.6	119.5	199.1	331.8
325	77.4	116.1	193.6	322.6
350	75.1	112.7	187.8	313.0
375	72.7	109.1	181.8	303.1
400	69.4	104.2	173.6	289.3
425	57.5	86.3	143.8	239.7
450	46.0	69.0	115.0	191.7
475	34.9	52.3	87.2	145.3
500	23.5	35.3	58.8	97.9
538	11.8	17.7	29.5	49.2

*Table B: pressure-temperature ratings for ASTM A350 LF2 flanges; Class 600, 900, 1500, 2500; Working pressure: bar; Temperature: °C.

Temp. °F	Working Pressures by Classes, psi
	75#	150#	300#	400#
-20~100	140	285	740	985
200	130	260	680	905
300	115	230	655	870
400	100	200	635	845
500	85	170	605	805
600	70	140	570	755
650	60	125	550	730
700	-	110	530	710
750	-	95	505	675
800	-	80	410	550
850	-	65	320	425
900	-	50	230	305
950	-	35	135	185
1000	-	20	85	115

*Table C: pressure-temperature ratings for ASTM A350 LF2 flanges; Class 75, 150, 300, 400; Working pressure: psi; Temperature: °F.

Temp. °F	Working Pressures by Classes, psi
	600#	900#	1500#	2500#
-20~100	1480	2220	3705	6170
200	1360	2035	3395	5655
300	1310	1965	3270	5450
400	1265	1900	3170	5280
500	1205	1810	3015	5025
600	1135	1705	2840	4730
650	1100	1650	2745	4575
700	1060	1590	2655	4425
750	1015	1520	2535	4230
800	825	1235	2055	3430
850	640	955	1595	2655
900	460	690	1150	1915
950	275	410	685	1145
1000	170	255	430	715

*Table D: pressure-temperature ratings for ASTM A350 LF2 flanges; Class 600, 900, 1500, 2500; Working pressure: psi; Temperature: °F.

Important Notes: Upon prolonged exposure to temperatures above 425°C, the carbide phase of steel may be converted to graphite. Permissible but not recommended for prolonged use above 425°C.