Weld Neck Flange Dimensions: ASME B16.5

ASME B16.5 is limited to flanges and flanged fittings made from cast or forged materials. B16.5 also includes requirements and recommendations regarding flange bolts, gaskets, and flanged joints. Careful application of these B16 Standards will help users to comply with applicable regulations within their jurisdictions while achieving the operational, cost, and safety benefits to be gained from the many industry best practices.

This page will cover key dimensions for ASME B16.5 Weld Neck Flanges From 1/2 NPS to 24 NPS with Pressure rating classes 150, 300, 400, 600, 900 & 1500.

If you would like to order proper Weld Neck flanges, typically You need to specify following details:

NPS size for Flange (EX: 8 NPS)
Type of Flange (EX: Weld Neck FF or Weld-neck RF)
Pressure Class (EX: Class 150)
Bore Diameter to Match ID of Pipe or Connecting Pipe Schedule (EX: SCH STD or 0.375W)
Organization name & Code that covers its specification (EX: ASME B16.5)
Finally, Material Specification & Code (EX: ASTM A182, 304L)

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

***Bore Dimensions are based on STD wall pipe**

Weld Neck Flange Dimension — WELD NECK CL150

Weld Neck Flange Class 150: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	3.50	0.38	1.38	1.19	4-0.62	2.38	0.88	0.84	1.81
2	¾	3.88	0.44	1.69	1.50	4-0.62	2.75	1.09	1.05	2.00
3	1	4.25	0.50	2.00	1.94	4-0.62	3.12	1.36	1.32	2.12
4	1¼	4.62	0.56	2.50	2.31	4-0.62	3.50	1.7	1.66	2.19
5	1½	5.00	0.62	2.88	2.56	4-0.62	3.88	1.95	1.90	2.38
6	2	6.00	0.69	3.62	3.06	4-0.75	4.75	2.44	2.38	2.44
7	2½	7.00	0.81	4.12	3.56	4-0.75	5.50	2.94	2.88	2.69
8	3	7.50	0.88	5.00	4.25	4-0.75	6.00	3.57	3.50	2.69
9	3½	8.50	0.88	5.50	4.81	8-0.75	7.00	4.07	4.00	2.75
10	4	9.00	0.88	6.19	5.31	8-0.75	7.50	4.57	4.50	2.94
11	5	10.00	0.88	7.31	6.44	8-0.88	8.50	5.66	5.56	3.44
12	6	11.00	0.94	8.50	7.56	8-0.88	9.50	6.72	6.63	3.44
13	8	13.50	1.06	10.62	9.69	8-0.88	11.75	8.72	8.63	3.94
14	10	16.00	1.12	12.75	12.00	12-1.00	14.25	10.88	10.75	3.94
15	12	19.00	1.19	15.00	14.38	12-1.00	17.00	12.88	12.75	4.44
16	14	21.00	1.31	16.25	15.75	12-1.12	18.75	14.14	14.00	4.94
17	16	23.50	1.38	18.50	18.00	16-1.12	21.25	16.16	16.00	4.94
18	18	25.00	1.50	21.00	19.88	16-1.25	22.75	18.18	18.00	5.44
19	20	27.50	1.62	23.00	22.00	20-1.25	25.00	20.2	20.00	5.62
20	22	29.50	1.75	25.25	24.25	20-1.38	27.25	22.22	22.00	5.82
21	24	32.00	1.81	27.25	26.12	20-1.38	29.50	24.25	24.00	5.94
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L

Weld Neck Flange Class 300: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	3.75	0.50	1.38	1.50	4-0.63	2.62	0.62	0.84	2.00
2	¾	4.62	0.56	1.69	1.88	4-0.75	3.25	0.82	1.05	2.19
3	1	4.88	0.62	2.00	2.12	4-0.75	3.50	1.05	1.32	2.38
4	1¼	5.25	0.69	2.50	2.50	4-0.75	3.88	1.38	1.66	2.50
5	1½	6.12	0.75	2.88	2.75	4-0.88	4.50	1.61	1.90	2.63
6	2	6.50	0.81	3.62	3.31	8-0.75	5.00	2.07	2.38	2.69
7	2½	7.50	0.94	4.12	3.94	8-0.88	5.88	2.47	2.88	2.94
8	3	8.25	1.06	5.00	4.62	8-0.88	6.62	3.07	3.50	3.06
9	3½	9.00	1.12	5.50	5.25	8-0.88	7.25	3.55	4.00	3.13
10	4	10.00	1.19	6.19	5.75	8-0.88	7.88	4.03	4.50	3.32
11	5	11.00	1.31	7.31	7.00	8-0.88	9.25	5.05	5.56	3.82
12	6	12.50	1.38	8.50	8.12	12-0.88	10.62	6.07	6.63	3.82
13	8	15.00	1.56	10.62	10.25	12-1.00	13.00	7.98	8.63	4.32
14	10	17.50	1.81	12.75	12.62	16-1.12	15.25	10.02	10.75	4.56
15	12	20.50	1.94	15.00	14.75	16-1.25	17.75	12	12.75	5.06
16	14	23.00	2.06	16.25	16.75	20-1.25	20.25	13.25	14.00	5.56
17	16	25.50	2.19	18.50	19.00	20-1.38	22.50	15.25	16.00	5.69
18	18	28.00	2.31	21.00	21.00	24-1.38	24.75	17.25	18.00	6.19
19	20	30.50	2.44	23.00	23.12	24-1.38	27.00	19.25	20.00	6.32
20	22	33.00	2.57	25.25	25.25	24-1.63	29.25	21.25	22.00	6.43
21	24	36.00	2.69	27.25	27.62	24-1.63	32.00	23.25	24.00	6.56
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L

Weld Neck Flange Class 400: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	3.75	0.56	1.38	1.50	4-0.63	2.62		0.84	2.06
2	¾	4.62	0.62	1.69	1.88	4-0.75	3.25		1.05	2.25
3	1	4.88	0.69	2.00	2.12	4- 75	3.50		1.32	2.44
4	1¼	5.25	0.81	2.50	2.50	4-0.75	3.88		1.66	2.62
5	1½	6.12	0.88	2.88	2.75	4-0.88	4.50		1.90	2.75
6	2	6.50	1.00	3.62	3.31	8-0.75	5.00		2.38	2.88
7	2½	7.50	1.12	4.12	3.94	8-0.88	5.88		2.88	3.12
8	3	8.25	1.25	5.00	4.62	8-0.88	6.62		3.50	3.25
9	3½	9.00	1.38	5.50	5.25	8-1.00	7.25		4.00	3.38
10	4	10.00	1.38	6.19	5.75	8-1.00	7.88		4.50	3.50
11	5	11.00	1.50	7.31	7.00	8-1.00	9.25		5.56	4.00
12	6	12.50	1.62	8.50	8.12	12-1.00	10.62		6.63	4.06
13	8	15.00	1.88	10.62	10.25	12-1.12	13.00		8.63	4.62
14	10	17.50	2.12	12.75	12.62	16-1.25	15.25		10.75	4.88
15	12	20.50	2.25	15.00	14.75	16-1.38	17.75		12.75	5.38
16	14	23.00	2.38	16.25	16.75	20-1.38	20.25		14.00	5.88
17	16	25.50	2.50	18.50	19.00	20-1.50	22.50		16.00	6.00
18	18	28.00	2.62	21.00	21.00	24-1.50	24.75		18.00	6.50
19	20	30.50	2.75	23.00	23.12	24-1.62	27.00		20.00	6.62
20	22	33.00	2.88	25.25	25.25	24-1.75	29.25		22.00	6.75
21	24	36.00	3.00	27.25	27.62	24-1.88	32.00		24.00	6.88
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L

Weld Neck Flange Class 600: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	3.75	0.56	1.38	1.50	4-0.63	2.62		0.84	2.06
2	¾	4.62	0.62	1.69	1.88	4-0.75	3.25		1.05	2.25
3	1	4.88	0.69	2.00	2.12	4-0.75	3.50		1.32	2.44
4	1¼	5.25	0.81	2.50	2.50	4-0.75	3.88		1.66	2.62
5	1½	6.12	0.88	2.88	2.75	4-0.88	4.50		1.90	2.75
6	2	6.50	1.00	3.62	3.31	8-0.75	5.00		2.38	2.88
7	2½	7.50	1.12	4.12	3.94	8-0.88	5.88		2.88	3.12
8	3	8.25	1.25	5.00	4.62	8-0.88	6.62		3.50	3.25
9	3½	9.00	1.38	5.50	5.25	8-1.00	7.25		4.00	3.38
10	4	10.75	1.50	6.19	6.00	8-1.00	8.50		4.50	4.00
11	5	13.00	1.75	7.31	7.44	8-1.12	10.50		5.56	4.50
12	6	14.00	1.88	8.50	8.75	12-1.12	11.50		6.63	4.62
13	8	16.50	2.19	10.62	10.75	12-1.25	13.75		8.63	5.25
14	10	20.00	2.50	12.75	13.50	16-1.38	17.00		10.75	6.00
15	12	22.00	2.62	15.00	15.75	20-1.38	19.25		12.75	6.12
16	14	23.75	2.75	16.25	17.00	20-1.50	20.75		14.00	6.50
17	16	27.00	3.00	18.50	19.50	20-1.63	23.75		16.00	7.00
18	18	29.25	3.25	21.00	21.50	20-1.75	25.75		18.00	7.25
19	20	32.00	3.50	23.00	24.00	24-1.75	28.50		20.00	7.50
20	22	34.25	3.75	25.25	26.25	24-1.75	30.63		22.00	7.75
21	24	37.00	4.00	27.25	28.25	24-2.00	33.00		24.00	8.00
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L

Weld Neck Flange Class 900: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	4.75	0.88	1.38	1.50	4-0.88	3.25		0.84	2.38
2	¾	5.12	1.00	1.69	1.75	4-0.88	3.50		1.05	2.75
3	1	5.88	1.12	2.00	2.06	4-1.00	4.00		1.32	2.88
4	1¼	6.25	1.12	2.50	2.50	4-1.00	4.38		1.66	2.88
5	1½	7.00	1.25	2.88	2.75	4-1.12	4.88		1.90	3.25
6	2	8.50	1.50	3.63	4.12	8-1.00	6.50		2.38	4.00
7	2½	9.62	1.62	4.13	4.88	8-1.12	7.50		2.88	4.12
8	3	9.50	1.50	5.00	5.00	8-1.00	7.50		3.50	4.00
10	4	11.50	1.75	6.19	6.25	8-1.25	9.25		4.50	4.50
11	5	13.75	2.00	7.31	7.50	8-1.38	11.00		5.56	5.00
12	6	15.00	2.19	8.50	9.25	12-1.25	12.50		6.63	5.50
13	8	18.50	2.50	10.63	11.75	12-1.50	15.50		8.63	6.38
14	10	21.50	2.75	12.75	14.50	16-1.50	18.50		10.75	7.25
15	12	24.00	3.12	15.00	16.50	20-1.50	21.00		12.75	7.88
16	14	25.25	3.38	16.25	17.75	20-1.63	22.00		14.00	8.38
17	16	27.75	3.50	18.50	20.00	20-1.75	24.25		16.00	8.50
18	18	31.00	4.00	21.00	22.25	20-2.00	27.00		18.00	9.00
19	20	33.75	4.25	23.00	24.50	20-2.13	29.50		20.00	9.75
21	24	41.00	5.50	27.25	29.50	20-2.63	35.50		24.00	11.50
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L

Weld Neck Flange Class 1500: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	4.75	0.88	1.38	1.50	4-0.88	3.25		0.84	2.38
2	¾	5.12	1.00	1.69	1.75	4-0.88	3.50		1.05	2.75
3	1	5.88	1.12	2.00	2.06	4-1.00	4.00		1.32	2.88
4	1¼	6.25	1.12	2.50	2.50	4-1.00	4.38		1.66	2.88
5	1½	7.00	1.25	2.88	2.75	4-1.12	4.88		1.90	3.25
6	2	8.50	1.50	3.63	4.12	8-1.00	6.50		2.38	4.00
7	2½	9.62	1.62	4.13	4.88	8-1.12	7.50		2.88	4.12
8	3	10.50	1.88	5.00	5.25	8-1.25	8.00		3.50	4.62
10	4	12.25	2.12	6.19	6.38	8-1.38	9.50		4.50	4.88
11	5	14.75	2.88	7.31	7.75	8-1.63	11.50		5.56	6.12
12	6	15.50	3.25	8.50	9.00	12-1.50	12.50		6.63	6.75
13	8	19.00	3.62	10.63	11.50	12-1.75	15.50		8.63	8.38
14	10	23.00	4.25	12.75	14.50	12-2.00	19.00		10.75	10.00
15	12	26.50	4.88	15.00	17.75	16-2.12	22.50		12.75	11.12
16	14	29.50	5.25	16.25	19.50	16-2.38	25.00		14.00	11.75
17	16	32.50	5.75	18.50	21.75	16-2.63	27.75		16.00	12.25
18	18	36.00	6.38	21.00	23.50	16-2.88	30.50		18.00	12.88
19	20	38.75	7.00	23.00	25.25	16-3.12	32.75		20.00	14.00
21	24	46.00	8.00	27.25	30.00	16-3.63	39.00		24.00	16.00
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L

Weld Neck Flange Class 2500: ASME B16.5

wdt_ID	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L
1	½	5.25	1.19	1.38	1.69	4-0.88	3.50		0.84	2.88
2	¾	5.50	1.25	1.69	2.00	4-0.88	3.75		1.05	3.12
3	1	6.25	1.38	2.00	2.25	4-1.00	4.25		1.32	3.50
4	1¼	7.25	1.50	2.50	2.88	4-1.12	5.13		1.66	3.75
5	1½	8.00	1.75	2.88	3.12	4-1.25	5.75		1.90	4.38
6	2	9.25	2.00	3.63	3.75	8-1.12	6.75		2.38	5.00
7	2½	10.50	2.25	4.13	4.50	8-1.25	7.75		2.88	5.62
8	3	12.00	2.62	5.00	5.25	8-1.38	9.00		3.50	6.62
10	4	14.00	3.00	6.19	6.50	8-1.63	10.75		4.50	7.50
11	5	16.50	3.62	7.31	8.00	8-1.88	12.75		5.56	9.00
12	6	19.00	4.25	8.50	9.25	8-2.12	14.50		6.63	10.75
13	8	21.75	5.00	10.63	12.00	12-2.12	17.25		8.63	12.50
14	10	26.50	6.50	12.75	14.75	12-2.63	21.25		10.75	16.50
15	12	30.00	7.25	15.00	17.38	12-2.88	24.38		12.75	18.25
	Nom. Pipe Size	O	T	R	X	# - Bolt Hole	B.C.D	Bore	H	L