ASME B18.31.2 Flange Bolting Studs

ASME B18.31.2 Flange Bolting Studs Standard provides dimensional and general data for flange bolting studs recognized as American National Standard in inch dimensions.
Flange bolting stud (stud bolt): a threaded stud used primarily in applications with pipe flanges covered by ASME B16.5 and manufactured using ASTM A01 bolting materials. These studs are typically used with two nuts to secure flange joints.
The inclusion of dimensional data in ASME B18.31.2 Standard is not intended to imply that all products described are stock production items. Consumers should consult with suppliers concerning availability of products.

ASME B18.31.2 Dimensions for Flange Bolting Studs (mm)

Nominal Size	Diameter, D	Chamfered Thread Distance, U
		UNC Threads		UNF Threads		8UN Threads
		Min.	Max.	Min.	Max.	Min.	Max.
1/4	6.350	1.270	2.540	0.914	1.803	…	…
5/16	7.938	1.422	2.819	1.067	2.108	…	…
3/8	9.525	1.600	3.175	1.067	2.108	…	…
7/16	11.113	1.829	3.632	1.270	2.540	…	…
1/2	12.700	1.956	3.912	1.270	2.540	…	…
9/16	14.288	2.134	4.242	1.422	2.819	…	…
5/8	15.875	2.311	4.623	1.422	2.819	…	…
3/4	19.050	2.540	5.080	1.600	3.175	…	…
7/8	22.225	2.819	5.639	1.829	3.632	…	…
1	25.400	3.175	6.350	2.134	4.242	…	…
1 1/8	28.575	3.632	7.264	2.134	4.242	3.175	6.350
1 1/4	31.750	3.632	7.264	2.134	4.242	3.175	6.350
1 3/8	34.925	4.242	8.458	2.134	4.242	3.175	6.350
1 1/2	38.100	4.242	8.458	2.134	4.242	3.175	6.350
1 5/8	41.275	…	…	…	…	3.175	6.350
1 3/4	44.450	5.080	10.160	…	…	3.175	6.350
1 7/8	47.625	…	…	…	…	3.175	6.350
2	50.800	5.639	11.278	…	…	3.175	6.350
2 1/4	57.150	5.639	11.278	…	…	3.175	6.350
2 1/2	63.500	6.350	12.700	…	…	3.175	6.350
2 3/4	69.850	6.350	12.700	…	…	3.175	6.350
3	76.200	6.350	12.700	…	…	3.175	6.350
3 1/4	82.550	6.350	12.700	…	…	3.175	6.350
3 1/2	88.900	6.350	12.700	…	…	3.175	6.350
3 3/4	95.250	6.350	12.700	…	…	3.175	6.350
4	101.600	6.350	12.700	…	…	3.175	6.350

ASME B18.31.2 Flange Bolting Stud Length Tolerances (mm)

Range, L	Tolerances
From 19.05 through 304.8	±1.575
Over 304.8 through 457.2	±3.175
Over 457.2	±6.350

ASME B18.31.2 Dimensions for Flange Bolting Studs (Inch)

Nominal Size	Diameter, D	Chamfered Thread Distance, U
		UNC Threads		UNF Threads		8UN Threads
		Min.	Max.	Min.	Max.	Min.	Max.
1/4	0.2500	0.050	0.100	0.036	0.071	…	…
5/16	0.3125	0.056	0.111	0.042	0.083	…	…
3/8	0.3750	0.063	0.125	0.042	0.083	…	…
7/16	0.4375	0.072	0.143	0.050	0.100	…	…
1/2	0.5000	0.077	0.154	0.050	0.100	…	…
9/16	0.5625	0.084	0.167	0.056	0.111	…	…
5/8	0.6250	0.091	0.182	0.056	0.111	…	…
3/4	0.7500	0.100	0.200	0.063	0.125	…	…
7/8	0.8750	0.111	0.222	0.072	0.143	…	…
1	1.0000	0.125	0.250	0.084	0.167	…	…
1 1/8	1.1250	0.143	0.286	0.084	0.167	0.125	0.250
1 1/4	1.2500	0.143	0.286	0.084	0.167	0.125	0.250
1 3/8	1.3750	0.167	0.333	0.084	0.167	0.125	0.250
1 1/2	1.5000	0.167	0.333	0.084	0.167	0.125	0.250
1 5/8	1.6250	…	…	…	…	0.125	0.250
1 3/4	1.7500	0.200	0.400	…	…	0.125	0.250
1 7/8	1.8750	…	…	…	…	0.125	0.250
2	2.0000	0.222	0.444	…	…	0.125	0.250
2 1/4	2.2500	0.222	0.444	…	…	0.125	0.250
2 1/2	2.5000	0.250	0.500	…	…	0.125	0.250
2 3/4	2.7500	0.250	0.500	…	…	0.125	0.250
3	3.0000	0.250	0.500	…	…	0.125	0.250
3 1/4	3.2500	0.250	0.500	…	…	0.125	0.250
3 1/2	3.5000	0.250	0.500	…	…	0.125	0.250
3 3/4	3.7500	0.250	0.500	…	…	0.125	0.250
4	4.0000	0.250	0.500	…	…	0.125	0.250

ASME B18.31.2 Flange Bolting Stud Length Tolerances (Inch)

Range, L	Tolerances
From ¾ through 12	±0.062
Over 12 through 18	±0.125
Over 18	±0.250