Stainless steel 304L and 316L flanges are the low carbon version of stainless steel 304 and 316, respectively. According to ASME B16.5, they may be manufactured from forgings (ASTM A182 Gr. F304L/ F316L) or plates (ASTM A240 Gr. 304L/ 316L), respectively. The working pressures for which SS 304L/316L flanges can be applied at elevated temperatures are listed in below 2 tables (it is also known as “pressure-temperature ratings” for the material).

Pressure-Temperature Ratings for SS 304L/316L Flanges

Temp. °F	Class 150	Class 300	Class 600
-20~100	230	600	1,200
200	195	510	1,020
300	175	455	910
400	160	420	840
500	150	395	785
600	140	370	745
650	125	365	730
700	110	360	720
750	95	355	705
800	80	345	690
850	65	340	675

*The working pressures by classes of 150, 300, 600, unit: psig.

Temp. °F	Class 900	Class 1500	Class 2500
-20~100	1,800	3,000	5,000
200	1,535	2,555	4,260
300	1,370	2,280	3,800
400	1,260	2,100	3,500
500	1,180	1,970	3,280
600	1,115	1,860	3,100
650	1,095	1,825	3,040
700	1,080	1,800	3,000
750	1,060	1,765	2,940
800	1,035	1,730	2,880
850	1,015	1,690	2,820

*The working pressures by classes of 900, 1500, 2500, unit: psig.

Since pipe flanges of Class 400 are rarely used in engineering practice, its data are not listed. All values in the above two tables are in US customary unit. You may contact us to get the technical specification in metric unit. Especially, SS 304L flanges are not to be used over 800°F.