ASME Flange Bolt Torque Chart (B16.5)

Projectmaterials

ASME Flange Bolt Torque Chart (B16.5)

Author: Editorial Team|9 min read

The following tables provide recommended bolt tightening torque values for ASME B16.5 flanges from Class 150 through Class 2500. All values are for ASTM A193 B7 stud bolts with ASTM A194 2H heavy hex nuts and PTFE-based gaskets, with properly lubricated threads. Torque values are expressed in both ft-lb and Nm for field reference.

Class 150 Flanges

Recommended bolt torque values for ASME B16.5 Class 150 raised face flanges.

NPS (Pipe Size)	Bolt Size	Number of Bolts	Torque (ft-lb)	Torque (Nm)
1/2”	1/2”	4	30	41
3/4”	1/2”	4	40	54
1”	1/2”	4	50	68
1-1/4”	1/2”	4	60	81
1-1/2”	1/2”	4	60	81
2”	5/8”	4	120	163
2-1/2”	5/8”	4	120	163
3”	5/8”	4	120	163
3-1/2”	5/8”	8	120	163
4”	5/8”	8	120	163
5”	3/4”	8	200	271
6”	3/4”	8	200	271
8”	3/4”	8	200	271
10”	7/8”	12	320	434
12”	7/8”	12	320	434
14”	1”	12	340	461
16”	1”	16	340	461
18”	1-1/8”	16	340	461
20”	1-1/8”	20	340	461
24”	1-1/4”	20	340	461

Class 300 Flanges

Recommended bolt torque values for ASME B16.5 Class 300 raised face flanges.

NPS (Pipe Size)	Bolt Size	Number of Bolts	Torque (ft-lb)	Torque (Nm)
1/2”	1/2”	4	60	81
3/4”	5/8”	4	80	108
1”	5/8”	4	100	136
1-1/4”	5/8”	4	110	149
1-1/2”	3/4”	4	150	203
2”	5/8”	8	110	149
2-1/2”	3/4”	8	140	190
3”	3/4”	8	200	271
3-1/2”	3/4”	8	200	271
4”	3/4”	8	200	271
5”	3/4”	8	200	271
6”	3/4”	12	200	271
8”	7/8”	12	320	434
10”	1”	16	420	569
12”	1-1/8”	16	490	664
14”	1-1/8”	20	490	664
16”	1-1/4”	20	530	719
18”	1-1/4”	24	530	719
20”	1-1/4”	24	530	719
24”	1-1/2”	24	560	759

Class 600 Flanges

Recommended bolt torque values for ASME B16.5 Class 600 raised face flanges.

NPS (Pipe Size)	Bolt Size	Number of Bolts	Torque (ft-lb)	Torque (Nm)
1/2”	1/2”	4	100	136
3/4”	5/8”	4	130	176
1”	5/8”	4	150	203
1-1/4”	5/8”	4	160	217
1-1/2”	3/4”	4	200	271
2”	5/8”	8	160	217
2-1/2”	3/4”	8	200	271
3”	3/4”	8	250	339
3-1/2”	7/8”	8	320	434
4”	7/8”	8	350	475
5”	1”	8	450	610
6”	1”	12	450	610
8”	1-1/8”	12	530	719
10”	1-1/4”	16	680	922
12”	1-1/4”	20	700	949
14”	1-3/8”	20	800	1085
16”	1-1/2”	20	900	1220
18”	1-5/8”	20	950	1288
20”	1-5/8”	24	1000	1356
24”	1-7/8”	24	1060	1437

Class 900 Flanges

Recommended bolt torque values for ASME B16.5 Class 900 raised face flanges.

NPS (Pipe Size)	Bolt Size	Number of Bolts	Torque (ft-lb)	Torque (Nm)
1/2”	3/4”	4	200	271
3/4”	3/4”	4	220	298
1”	7/8”	4	280	380
1-1/4”	7/8”	4	300	407
1-1/2”	1”	4	350	475
2”	7/8”	8	320	434
2-1/2”	1”	8	400	542
3”	7/8”	8	350	475
4”	1-1/8”	8	500	678
5”	1-1/4”	8	600	813
6”	1-1/8”	12	530	719
8”	1-3/8”	12	750	1017
10”	1-3/8”	16	800	1085
12”	1-3/8”	20	850	1153
14”	1-1/2”	20	950	1288
16”	1-5/8”	20	1050	1424
18”	1-7/8”	20	1150	1559
20”	2”	20	1200	1627
24”	2-1/2”	20	1280	1736

Class 1500 Flanges

Recommended bolt torque values for ASME B16.5 Class 1500 raised face flanges.

NPS (Pipe Size)	Bolt Size	Number of Bolts	Torque (ft-lb)	Torque (Nm)
1/2”	3/4”	4	300	407
3/4”	3/4”	4	330	447
1”	7/8”	4	400	542
1-1/4”	7/8”	4	420	569
1-1/2”	1”	4	500	678
2”	7/8”	8	450	610
2-1/2”	1”	8	550	746
3”	1-1/8”	8	650	881
4”	1-1/4”	8	750	1017
5”	1-1/2”	8	950	1288
6”	1-3/8”	12	850	1153
8”	1-5/8”	12	1100	1491
10”	1-7/8”	12	1350	1831
12”	2”	16	1500	2034
14”	2-1/4”	16	1650	2237
16”	2-1/2”	16	1800	2441
18”	2-3/4”	16	1950	2644
20”	3”	16	2050	2780
24”	3-1/2”	16	2190	2969

Class 2500 Flanges

Recommended bolt torque values for ASME B16.5 Class 2500 raised face flanges.

NPS (Pipe Size)	Bolt Size	Number of Bolts	Torque (ft-lb)	Torque (Nm)
1/2”	3/4”	4	500	678
3/4”	3/4”	4	550	746
1”	7/8”	4	650	881
1-1/4”	1”	4	750	1017
1-1/2”	1-1/8”	4	850	1153
2”	1”	8	750	1017
2-1/2”	1-1/8”	8	900	1220
3”	1-1/4”	8	1050	1424
4”	1-1/2”	8	1350	1831
5”	1-3/4”	8	1700	2305
6”	2”	8	2100	2847
8”	2-1/4”	12	2500	3390
10”	2-3/4”	12	2900	3932
12”	3”	12	3200	4339

Notes

All torque values in these tables are for ASTM A193 Grade B7 stud bolts with ASTM A194 Grade 2H heavy hex nuts and PTFE-based (e.g., Garlock, Teadit) gaskets. Threads are assumed to be properly lubricated with anti-seize compound or machine oil.
Torque requirements change significantly based on gasket type. Spiral wound gaskets (ASME B16.20) generally require higher torque than PTFE gaskets to achieve proper seating stress. Ring-type joint (RTJ) gaskets require different values altogether. Always refer to the gasket manufacturer’s recommended seating stress when available.
These values are for general guidance only. Always follow site-specific procedures, project specifications, and the flange joint assembly instructions provided by the engineering team. Critical flanges in high-pressure or high-temperature service should be assembled per ASME PCC-1 guidelines using qualified personnel.
Apply torque in a minimum of three passes using a cross-pattern (star) tightening sequence: first pass at approximately 30% of the final value, second pass at approximately 60%, and third pass at 100% of the final torque. A fourth verification pass is recommended for critical service.
Dry or unlubricated bolts will produce significantly lower bolt tension for the same applied torque (up to 20-30% reduction). Always ensure threads and nut-bearing surfaces are properly lubricated before torquing.