Group 2.3 Pressure-Temperature Ratings

Low-carbon (L-grade) austenitic stainless steels, including 317L. The lower carbon buys weld-decay resistance at the cost of a slightly lower allowable stress than the standard grades. ASME B16.5 does not publish ratings for this group above 850 °F.

Standard: ASME B16.5
Group: Group 2.3
Materials: A182 F304L, A182 F316L, A182 F317L, A240 304L, A240 316L
Class 150 at 100 °F: 230 psig (15.9 bar)
Class 150 at 600 °F: 140 psig (9.7 bar)

ASME B16.5 pressure-temperature ratings for Group 2.3 materials, in psig.
Class	100 °F	200 °F	300 °F	400 °F	500 °F	600 °F	650 °F	700 °F	750 °F	800 °F	850 °F
Class 150	230	195	175	160	150	140	125	110	95	80	65
Class 300	600	510	455	420	395	370	365	360	355	345	340
Class 400	800	680	610	560	525	495	485	480	470	460	450
Class 600	1200	1020	910	840	785	745	730	720	705	690	675
Class 900	1800	1535	1370	1260	1180	1115	1095	1080	1060	1035	1015
Class 1500	3000	2555	2280	2100	1970	1860	1825	1800	1765	1730	1690
Class 2500	5000	4260	3800	3500	3280	3100	3040	3000	2940	2880	2820

Interpolation between listed temperatures is permitted; extrapolation is not. ASME B16.5 does not publish a rating for this group above 850 °F.

How far this table has been checked. Type 304L is not to be used above 800 °F, so the 850 °F column applies to 316L and 317L only. None of the values on this site has been checked against the standard itself; see how the figures are checked.

What Group 2.3 is used for

These are the low-carbon L grades of austenitic stainless steel. The lower carbon protects the weld zone from intergranular corrosion, and it costs some strength, so the ratings sit below those of the standard grades and the table stops at a lower temperature.

Reading the ratings

A Class 300 flange in Group 2.3 is rated 600 psig at 100 °F, 370 psig at 600 °F and 340 psig at 850 °F, which is 57% of its cold rating. Every other class in the group follows the same curve, scaled by the class. Group 1.1 carbon steel is rated 740 psig at 100 °F, so this group starts lower. It passes carbon steel at 850 °F, where it is rated 340 psig against 320 psig.

Each figure is the highest gauge pressure the flange may see at that metal temperature. To use the table, fix the material group and the design temperature first, read down to find the lowest class whose rating is at or above the design pressure, and interpolate between columns if the temperature falls between them. The rating of the flange is often what limits a line, since the pipe wall is usually good for more.

Guides and comparisons for this page

Pressure-temperature deratingReading a P-T table and interpolating between temperatures.Hydrostatic test pressureWhat a line is tested at, and what its flanges allow.Pipe material selectionA53, A106, A312 and A335: which grade suits which duty.304 vs 316 stainless steel pipeWhat the molybdenum in 316 buys.Class 150 vs Class 300Dimensions, bolting and ratings of the two commonest classes.

Common questions

Which materials are in ASME B16.5 Group 2.3?

A182 F304L, A182 F316L, A182 F317L, A240 304L, A240 316L.

What is a Class 300 Group 2.3 flange rated at 600 °F?

370 psig (25.5 bar). At 100 °F the same flange is rated 600 psig (41.4 bar).

Other material groups

Group 1.1 Group 1.2 Group 2.1 Group 2.2 Group 1.9 Group 1.10 Group 1.15