ASME B16.5 Flange Bolting Chart

Stud count, diameter and length for ASME B16.5 flanges, Class 150 through 2500, for raised face and ring joint facings. Bolt counts and sizes are cross-checked against ASME PCC-1-2026 Table L-1. A printable PDF (PB-TD-212) is below. Values are for reference; confirm against the current edition of the governing standard. Send us your bolting list for a quote or call (281) 581-0176.

Notes

Stud lengths are first thread to first thread and do not include the points.
Raised face lengths: 0.06 in. raised face for Class 150 and 300, 0.25 in. for Class 400 and above.
Class 400 flanges NPS 3-1/2 and smaller use Class 600 dimensions. Class 900 flanges NPS 2-1/2 and smaller use Class 1500 dimensions.
Lengths assume a single heavy hex nut each end and no washers. For washers, double nuts or tensioning, use the Stud Bolt Length Calculator.

Bolting by class

Class 150

NPS	Bolts × dia., in.	Stud length, 0.06 in. RF	Stud length, ring joint
1/2	4 × 1/2	2-1/4	–
3/4	4 × 1/2	2-1/2	–
1	4 × 1/2	2-1/2	3
1-1/4	4 × 1/2	2-3/4	3-1/4
1-1/2	4 × 1/2	2-3/4	3-1/4
2	4 × 5/8	3-1/4	3-3/4
2-1/2	4 × 5/8	3-1/2	4
3	4 × 5/8	3-1/2	4
3-1/2	8 × 5/8	3-1/2	4
4	8 × 5/8	3-1/2	4
5	8 × 3/4	3-3/4	4-1/4
6	8 × 3/4	4	4-1/2
8	8 × 3/4	4-1/4	4-3/4
10	12 × 7/8	4-1/2	5
12	12 × 7/8	4-3/4	5-1/4
14	12 × 1	5-1/4	5-3/4
16	16 × 1	5-1/4	5-3/4
18	16 × 1-1/8	5-3/4	6-1/4
20	20 × 1-1/8	6-1/4	6-3/4
24	20 × 1-1/4	6-3/4	7-1/4

Class 300

NPS	Bolts × dia., in.	Stud length, 0.06 in. RF	Stud length, ring joint
1/2	4 × 1/2	2-1/2	3
3/4	4 × 5/8	3	3-1/2
1	4 × 5/8	3	3-1/2
1-1/4	4 × 5/8	3-1/4	3-3/4
1-1/2	4 × 3/4	3-1/2	4
2	8 × 5/8	3-1/2	4
2-1/2	8 × 3/4	4	4-1/2
3	8 × 3/4	4-1/4	4-3/4
3-1/2	8 × 3/4	4-1/4	5
4	8 × 3/4	4-1/2	5
5	8 × 3/4	4-3/4	5-1/4
6	12 × 3/4	4-3/4	5-1/2
8	12 × 7/8	5-1/2	6
10	16 × 1	6-1/4	6-3/4
12	16 × 1-1/8	6-3/4	7-1/4
14	20 × 1-1/8	7	7-1/2
16	20 × 1-1/4	7-1/2	8
18	24 × 1-1/4	7-3/4	8-1/4
20	24 × 1-1/4	8	8-3/4
24	24 × 1-1/2	9	10

Class 400

NPS	Bolts × dia., in.	Stud length, 0.25 in. RF	Stud length, ring joint
1/2	4 × 1/2	3	3
3/4	4 × 5/8	3-1/2	3-1/2
1	4 × 5/8	3-1/2	3-1/2
1-1/4	4 × 5/8	3-3/4	3-3/4
1-1/2	4 × 3/4	4-1/4	4-1/4
2	8 × 5/8	4-1/4	4-1/4
2-1/2	8 × 3/4	4-3/4	4-3/4
3	8 × 3/4	5	5
3-1/2	8 × 7/8	5-1/2	5-1/2
4	8 × 7/8	5-1/2	5-1/2
5	8 × 7/8	5-3/4	5-3/4
6	12 × 7/8	6	6
8	12 × 1	6-3/4	6-3/4
10	16 × 1-1/8	7-1/2	7-1/2
12	16 × 1-1/4	8	8
14	20 × 1-1/4	8-1/4	8-1/4
16	20 × 1-3/8	8-3/4	8-3/4
18	24 × 1-3/8	9	9
20	24 × 1-1/2	9-1/2	9-3/4
24	24 × 1-3/4	10-1/2	11

Class 600

NPS	Bolts × dia., in.	Stud length, 0.25 in. RF	Stud length, ring joint
1/2	4 × 1/2	3	3
3/4	4 × 5/8	3-1/2	3-1/2
1	4 × 5/8	3-1/2	3-1/2
1-1/4	4 × 5/8	3-3/4	3-3/4
1-1/2	4 × 3/4	4-1/4	4-1/4
2	8 × 5/8	4-1/4	4-1/4
2-1/2	8 × 3/4	4-3/4	4-3/4
3	8 × 3/4	5	5
3-1/2	8 × 7/8	5-1/2	5-1/2
4	8 × 7/8	5-3/4	5-3/4
5	8 × 1	6-1/2	6-1/2
6	12 × 1	6-3/4	6-3/4
8	12 × 1-1/8	7-1/2	7-3/4
10	16 × 1-1/4	8-1/2	8-1/2
12	20 × 1-1/4	8-3/4	8-3/4
14	20 × 1-3/8	9-1/4	9-1/4
16	20 × 1-1/2	10	10
18	20 × 1-5/8	10-3/4	10-3/4
20	24 × 1-5/8	11-1/4	11-1/2
24	24 × 1-7/8	13	13-1/4

Class 900

NPS	Bolts × dia., in.	Stud length, 0.25 in. RF	Stud length, ring joint
1/2	4 × 3/4	4-1/4	4-1/4
3/4	4 × 3/4	4-1/2	4-1/2
1	4 × 7/8	5	5
1-1/4	4 × 7/8	5	5
1-1/2	4 × 1	5-1/2	5-1/2
2	8 × 7/8	5-3/4	5-3/4
2-1/2	8 × 1	6-1/4	6-1/4
3	8 × 7/8	5-3/4	5-3/4
4	8 × 1-1/8	6-3/4	6-3/4
5	8 × 1-1/4	7-1/2	7-1/2
6	12 × 1-1/8	7-1/2	7-3/4
8	12 × 1-3/8	8-3/4	8-3/4
10	16 × 1-3/8	9-1/4	9-1/4
12	20 × 1-3/8	10	10
14	20 × 1-1/2	10-3/4	11
16	20 × 1-5/8	11-1/4	11-1/2
18	20 × 1-7/8	12-3/4	13-1/4
20	20 × 2	13-3/4	14-1/4
24	20 × 2-1/2	17-1/4	18

Class 1500

NPS	Bolts × dia., in.	Stud length, 0.25 in. RF	Stud length, ring joint
1/2	4 × 3/4	4-1/4	4-1/4
3/4	4 × 3/4	4-1/2	4-1/2
1	4 × 7/8	5	5
1-1/4	4 × 7/8	5	5
1-1/2	4 × 1	5-1/2	5-1/2
2	8 × 7/8	5-3/4	5-3/4
2-1/2	8 × 1	6-1/4	6-1/4
3	8 × 1-1/8	7	7
4	8 × 1-1/4	7-3/4	7-3/4
5	8 × 1-1/2	9-3/4	9-3/4
6	12 × 1-3/8	10-1/4	10-1/2
8	12 × 1-5/8	11-1/2	11-3/4
10	12 × 1-7/8	13-1/4	13-1/2
12	16 × 2	14-3/4	15-1/4
14	16 × 2-1/4	16	16-3/4
16	16 × 2-1/2	17-1/2	18-1/2
18	16 × 2-3/4	19-1/2	20-3/4
20	16 × 3	21-1/4	22-1/4
24	16 × 3-1/2	24-1/4	25-1/2

Class 2500

NPS	Bolts × dia., in.	Stud length, 0.25 in. RF	Stud length, ring joint
1/2	4 × 3/4	4-3/4	4-3/4
3/4	4 × 3/4	5	5
1	4 × 7/8	5-1/2	5-1/2
1-1/4	4 × 1	6	6
1-1/2	4 × 1-1/8	6-3/4	6-3/4
2	8 × 1	7	7
2-1/2	8 × 1-1/8	7-3/4	8
3	8 × 1-1/4	8-3/4	9
4	8 × 1-1/2	10	10-1/4
5	8 × 1-3/4	11-3/4	12-1/4
6	8 × 2	13-1/2	14
8	12 × 2	15	15-1/2
10	12 × 2-1/2	19-1/4	20
12	12 × 2-3/4	21-1/4	22

References: ASME B16.5, Pipe Flanges and Flanged Fittings · ASME PCC-1-2026, Guidelines for Pressure Boundary Bolted Flange Joint Assembly. Summaries are paraphrased; clause numbers refer to ASME PCC-1-2026 unless noted. Patriot Bolt manufactures bolting and does not perform bolting, training or joint assembly services.

(281) 581-0176

sales@patriotbolt.com

1974 S Houston Ave, Humble, TX 77396

Notes

Bolting by class