Group 2.2 Pressure-Temperature Ratings

Type 316 and 317 austenitic stainless steel. The molybdenum that gives these grades their corrosion resistance also gives them a slightly higher rating than Type 304 at every temperature above ambient.

Standard: ASME B16.5
Group: Group 2.2
Materials: A182 F316, A182 F316H, A182 F317, A351 CF3M, A351 CF8M, A351 CG8M, A240 316, A240 316H, A240 317
Class 150 at 100 °F: 275 psig (19.0 bar)
Class 150 at 600 °F: 140 psig (9.7 bar)

ASME B16.5 pressure-temperature ratings for Group 2.2 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	900 °F	950 °F	1000 °F
Class 150	275	235	215	195	170	140	125	110	95	80	65	50	35	20
Class 300	720	620	560	515	480	450	440	435	425	420	420	415	385	365
Class 400	960	825	745	685	635	600	590	580	570	565	555	555	515	485
Class 600	1440	1240	1120	1025	955	900	885	870	855	845	835	830	775	725
Class 900	2160	1860	1680	1540	1435	1355	1325	1305	1280	1265	1255	1245	1160	1090
Class 1500	3600	3095	2795	2570	2390	2255	2210	2170	2135	2110	2090	2075	1930	1820
Class 2500	6000	5160	4660	4280	3980	3760	3680	3620	3560	3520	3480	3460	3220	3030

Interpolation between listed temperatures is permitted; extrapolation is not.

How far this table has been checked. One secondary source gives values that differ by 5 to 10 psig in a few cells at 900 °F and above, probably from an earlier edition. The values here are those on which three other sources agree. None of the values on this site has been checked against the standard itself; see how the figures are checked.

What Group 2.2 is used for

This is Type 316 and Type 317, the austenitic stainless steels that contain molybdenum. They are chosen over Type 304 where chlorides or aggressive process chemistry would pit it, and they carry a slightly higher rating than Type 304 when hot.

Reading the ratings

A Class 300 flange in Group 2.2 is rated 720 psig at 100 °F, 450 psig at 600 °F and 365 psig at 1000 °F, which is 51% 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 800 °F, where it is rated 420 psig against 410 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 2.2?

A182 F316, A182 F316H, A182 F317, A351 CF3M, A351 CF8M, A351 CG8M, A240 316, A240 316H, A240 317.

What is a Class 300 Group 2.2 flange rated at 600 °F?

450 psig (31.0 bar). At 100 °F the same flange is rated 720 psig (49.6 bar).

Other material groups

Group 1.1 Group 1.2 Group 2.1 Group 2.3 Group 1.9 Group 1.10 Group 1.15