Threaded Flange Dimensions: ASME B16.5

Threaded flanges are similar in dimensions to slip-on flanges but instead of the plain bore, it is equipped with tapered pipe thread conforming to ASME B1.20.1. It is mostly used in an area where welding is not possible such as highly explosive and flammable areas.

Although they come in sizes 1/2 NPS to 24 NPS for most classes, many engineering companies limit their uses to a maximum of 4 NPS. Personally, I also won’t recommend to use threaded flanges larger than 4 NPS.

This page will cover key dimensions for ASME B16.5 Threaded Flanges From 1/2 NPS to 4 NPS with Pressure rating classes 150, 300, 400, 600, 900, 1500, & 2500. Only CL300 and above threaded flanges are made with counterbore.

Please click on blow link for more information about:

ASME B16.5 Dimensional Tolerances & Welding Bevel Standards
ASME B16.5 Bolt & Stud Dimensions
ASME B16.47 A/B Large Diameter Flange Dimension from 26 NPS to 60 NPS

Threaded Flange Dimension — Threaded Flange CL150

Threaded Flange Class 150: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	THRD
1	½	3.50	0.38	1.38	1.19	4-0.62	2.38	0.56	0.62
2	¾	3.88	0.44	1.69	1.50	4-0.62	2.75	0.56	0.62
3	1	4.25	0.50	2.00	1.94	4-0.62	3.12	0.62	0.69
4	1¼	4.62	0.56	2.50	2.31	4-0.62	3.50	0.75	0.81
5	1½	5.00	0.62	2.88	2.56	4-0.62	3.88	0.81	0.88
6	2	6.00	0.69	3.62	3.06	4-0.75	4.75	0.94	1.00
7	2½	7.00	0.81	4.12	3.56	4-0.75	5.50	1.06	1.12
8	3	7.50	0.88	5.00	4.25	4-0.75	6.00	1.12	1.19
9	3½	8.50	0.88	5.50	4.81	8-0.75	7.00	1.19	1.25
10	4	9.00	0.88	6.19	5.31	8-0.75	7.50	1.25	1.31
11	5	10.00	0.88	7.31	6.44	8-0.88	8.50	1.38	1.44
12	6	11.00	0.94	8.50	7.56	8-0.88	9.50	1.50	1.56
13	8	13.50	1.06	10.62	9.69	8-0.88	11.75	1.69	1.75
14	10	16.00	1.12	12.75	12.00	12-1.00	14.25	1.88	1.94
15	12	19.00	1.19	15.00	14.38	12-1.00	17.00	2.12	2.19
16	14	21.00	1.31	16.25	15.75	12-1.12	18.75	2.19	2.25
17	16	23.50	1.38	18.50	18.00	16-1.12	21.25	2.44	2.50
18	18	25.00	1.50	21.00	19.88	16-1.25	22.75	2.62	2.69
19	20	27.50	1.62	23.00	22.00	20-1.25	25.00	2.81	2.88
20	22	29.50	1.75	25.25	24.25	20-1.38	27.25	3.07	3.13
21	24	32.00	1.81	27.25	26.12	20-1.38	29.50	3.19	3.25
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	THRD

N/A* – Counterbore is not applicable for the CL150 flange.

Threaded Flange Class 300: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD
1	½	3.75	0.50	1.38	1.50	4-0.63	2.62	0.81	0.93	0.62
2	¾	4.62	0.56	1.69	1.88	4-0.75	3.25	0.94	1.14	0.62
3	1	4.88	0.62	2.00	2.12	4-0.75	3.50	1.00	1.41	0.69
4	1¼	5.25	0.69	2.50	2.50	4-0.75	3.88	1.00	1.75	0.81
5	1½	6.12	0.75	2.88	2.75	4-0.88	4.50	1.13	1.98	0.88
6	2	6.50	0.81	3.62	3.31	8-0.75	5.00	1.25	2.50	1.12
7	2½	7.50	0.94	4.12	3.94	8-0.88	5.88	1.44	3.00	1.25
8	3	8.25	1.06	5.00	4.62	8-0.88	6.62	1.63	3.63	1.25
9	3½	9.00	1.12	5.50	5.25	8-0.88	7.25	1.69	4.13	1.44
10	4	10.00	1.19	6.19	5.75	8-0.88	7.88	1.82	4.63	1.44
11	5	11.00	1.31	7.31	7.00	8-0.88	9.25	1.94	5.69	1.69
12	6	12.50	1.38	8.50	8.12	12-0.88	10.62	2.00	6.75	1.81
13	8	15.00	1.56	10.62	10.25	12-1.00	13.00	2.38	8.75	2.00
14	10	17.50	1.81	12.75	12.62	16-1.12	15.25	2.56	10.88	2.19
15	12	20.50	1.94	15.00	14.75	16-1.25	17.75	2.82	12.94	2.38
16	14	23.00	2.06	16.25	16.75	20-1.25	20.25	2.94	14.19	2.50
17	16	25.50	2.19	18.50	19.00	20-1.38	22.50	3.19	16.19	2.69
18	18	28.00	2.31	21.00	21.00	24-1.38	24.75	3.44	18.19	2.75
19	20	30.50	2.44	23.00	23.12	24-1.38	27.00	3.69	20.19	2.88
20	22	33.00	2.57	25.25	25.25	24-1.63	29.25	3.93	22.19	3.13
21	24	36.00	2.69	27.25	27.62	24-1.63	32.00	4.13	24.19	3.25
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD

Threaded Flange Class 400: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD
1	½	3.75	0.56	1.38	1.50	4-0.63	2.62	0.88	0.93	0.62
2	¾	4.62	0.62	1.69	1.88	4-0.75	3.25	1.00	1.14	0.62
3	1	4.88	0.69	2.00	2.12	4- 75	3.50	1.06	1.41	0.69
4	1¼	5.25	0.81	2.50	2.50	4-0.75	3.88	1.12	1.75	0.81
5	1½	6.12	0.88	2.88	2.75	4-0.88	4.50	1.25	1.99	0.88
6	2	6.50	1.00	3.62	3.31	8-0.75	5.00	1.44	2.50	1.12
7	2½	7.50	1.12	4.12	3.94	8-0.88	5.88	1.62	3.00	1.25
8	3	8.25	1.25	5.00	4.62	8-0.88	6.62	1.81	3.63	1.38
9	3½	9.00	1.38	5.50	5.25	8-1.00	7.25	1.94	4.13	1.56
10	4	10.00	1.38	6.19	5.75	8-1.00	7.88	2.00	4.63	1.44
11	5	11.00	1.50	7.31	7.00	8-1.00	9.25	2.12	5.69	1.69
12	6	12.50	1.62	8.50	8.12	12-1.00	10.62	2.25	6.75	1.81
13	8	15.00	1.88	10.62	10.25	12-1.12	13.00	2.69	8.75	2.00
14	10	17.50	2.12	12.75	12.62	16-1.25	15.25	2.88	10.88	2.19
15	12	20.50	2.25	15.00	14.75	16-1.38	17.75	3.12	12.94	2.38
16	14	23.00	2.38	16.25	16.75	20-1.38	20.25	3.31	14.19	2.50
17	16	25.50	2.50	18.50	19.00	20-1.50	22.50	3.69	16.19	2.69
18	18	28.00	2.62	21.00	21.00	24-1.50	24.75	3.88	18.19	2.75
19	20	30.50	2.75	23.00	23.12	24-1.62	27.00	4.00	20.19	2.88
20	24	36.00	3.00	27.25	27.62	24-1.88	32.00	4.50	24.19	3.25
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD

Threaded Flange Class 600: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD
1	½	3.75	0.56	1.38	1.50	4-0.63	2.62	0.88	0.93	0.62
2	¾	4.62	0.62	1.69	1.88	4-0.75	3.25	1.00	1.14	0.62
3	1	4.88	0.69	2.00	2.12	4-0.75	3.50	1.06	1.41	0.69
4	1¼	5.25	0.81	2.50	2.50	4-0.75	3.88	1.12	1.75	0.81
5	1½	6.12	0.88	2.88	2.75	4-0.88	4.50	1.25	1.99	0.88
6	2	6.50	1.00	3.62	3.31	8-0.75	5.00	1.44	2.50	1.12
7	2½	7.50	1.12	4.12	3.94	8-0.88	5.88	1.62	3.00	1.25
8	3	8.25	1.25	5.00	4.62	8-0.88	6.62	1.81	3.63	1.38
9	3½	9.00	1.38	5.50	5.25	8-1.00	7.25	1.94	4.13	1.56
10	4	10.75	1.50	6.19	6.00	8-1.00	8.50	2.12	4.63	1.62
11	5	13.00	1.75	7.31	7.44	8-1.12	10.50	2.38	5.69	1.88
12	6	14.00	1.88	8.50	8.75	12-1.12	11.50	2.62	6.75	2.00
13	8	16.50	2.19	10.62	10.75	12-1.25	13.75	3.00	8.75	2.25
14	10	20.00	2.50	12.75	13.50	16-1.38	17.00	3.38	10.88	2.56
15	12	22.00	2.62	15.00	15.75	20-1.38	19.25	3.62	12.94	2.75
16	14	23.75	2.75	16.25	17.00	20-1.50	20.75	3.69	14.19	2.88
17	16	27.00	3.00	18.50	19.50	20-1.63	23.75	4.19	16.19	3.06
18	18	29.25	3.25	21.00	21.50	20-1.75	25.75	4.62	18.19	3.12
19	20	32.00	3.50	23.00	24.00	24-1.75	28.50	5.00	20.19	3.25
20	24	37.00	4.00	27.25	28.25	24-2.00	33.00	5.50	24.19	3.62
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD

Threaded Flange Class 900: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD
1	½	4.75	0.88	1.38	1.50	4-0.88	3.25	1.25	0.93	0.88
2	¾	5.12	1.00	1.69	1.75	4-0.88	3.50	1.38	1.14	1.00
3	1	5.88	1.12	2.00	2.06	4-1.00	4.00	1.62	1.41	1.12
4	1¼	6.25	1.12	2.50	2.50	4-1.00	4.38	1.62	1.75	1.19
5	1½	7.00	1.25	2.88	2.75	4-1.12	4.88	1.75	1.99	1.25
6	2	8.50	1.50	3.63	4.12	8-1.00	6.50	2.25	2.50	1.50
7	2½	9.62	1.62	4.13	4.88	8-1.12	7.50	2.50	3.00	1.88
8	3	9.50	1.50	5.00	5.00	8-1.00	7.50	2.12	3.63	1.62
9	4	11.50	1.75	6.19	6.25	8-1.25	9.25	2.75	4.63	1.88
10	5	13.75	2.00	7.31	7.50	8-1.38	11.00	3.12	5.69	2.12
11	6	15.00	2.19	8.50	9.25	12-1.25	12.50	3.38	6.75	2.25
12	8	18.50	2.50	10.63	11.75	12-1.50	15.50	4.00	8.75	2.50
13	10	21.50	2.75	12.75	14.50	16-1.50	18.50	4.25	10.88	2.81
14	12	24.00	3.12	15.00	16.50	20-1.50	21.00	4.63	12.94	3.00
15	14	25.25	3.38	16.25	17.75	20-1.63	22.00	5.12	14.19	3.25
16	16	27.75	3.50	18.50	20.00	20-1.75	24.25	5.25	16.19	3.38
17	18	31.00	4.00	21.00	22.25	20-2.00	27.00	6.00	18.19	3.50
18	20	33.75	4.25	23.00	24.50	20-2.13	29.50	6.25	20.19	3.62
19	24	41.00	5.50	27.25	29.50	20-2.63	35.50	8.00	24.19	4.00
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD

Threaded Flange Class 1500: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD
1	½	4.75	0.88	1.38	1.50	4-0.88	3.25	1.25	0.93	0.88
2	¾	5.12	1.00	1.69	1.75	4-0.88	3.50	1.38	1.14	1.00
3	1	5.88	1.12	2.00	2.06	4-1.00	4.00	1.62	1.41	1.12
4	1¼	6.25	1.12	2.50	2.50	4-1.00	4.38	1.62	1.75	1.19
5	1½	7.00	1.25	2.88	2.75	4-1.12	4.88	1.75	1.99	1.25
6	2	8.50	1.50	3.63	4.12	8-1.00	6.50	2.25	2.50	1.50
7	2½	9.62	1.62	4.13	4.88	8-1.12	7.50	2.50	3.00	1.88
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD

Threaded Flange Class 2500: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD
1	½	5.25	1.19	1.38	1.69	4-0.88	3.50	1.56	0.93	1.12
2	¾	5.50	1.25	1.69	2.00	4-0.88	3.75	1.69	1.14	1.25
3	1	6.25	1.38	2.00	2.25	4-1.00	4.25	1.88	1.41	1.38
4	1¼	7.25	1.50	2.50	2.88	4-1.12	5.13	2.06	1.75	1.50
5	1½	8.00	1.75	2.88	3.12	4-1.25	5.75	2.38	1.99	1.75
6	2	9.25	2.00	3.63	3.75	8-1.12	6.75	2.75	2.50	2.00
7	2½	10.50	2.25	4.13	4.50	8-1.25	7.75	3.12	3.00	2.25
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	L	C	THRD