ANSI B16.5 Class 900 Forged Flanges

Weld Neck Forged Flange

Threaded Forged Flange

Lap Joint Forged Flange

Blind Forged Flange

Slip On Forged Flange

Nom. Pipe Size	O	T	R	X	#/Dia of Holesa	Bolt Circle Dia	B	B2b	B3	H	L	L2	L3c	r	C	Thr
Sizes 1/2" through 2 1/2" are identical to class 1500.
3	9.5	1.5	5	5	8-1.00	7.5	3.57		3.6	3.5	2.12	4	2.12	0.38	3.63	1.62
4	11.5	1.75	6.19	6.25	8-1.25	9.25	4.57		4.6	4.5	2.75	4.5	2.75	0.44	4.63	1.88
5	13.75	2	7.31	7.5	8-1.38	11	5.66		5.69	5.56	3.12	5	3.12	0.44	5.69	2.12
6	15	2.19	8.5	9.25	12-1.25	12.5	6.72		6.75	6.63	3.38	5.5	3.38	0.5	6.75	2.25
8	18.5	2.5	10.63	11.75	12-1.50	15.5	8.72		8.75	8.63	4	6.38	4.5	0.5	8.75	2.5
10	21.5	2.75	12.75	14.5	16-1.50	18.5	10.88		10.92	10.75	4.25	7.25	5	0.5	10.88	2.81
12	24	3.12	15	16.5	20-1.50	21	12.88		12.92	12.75	4.63	7.88	5.62	0.5	12.94	3
14	25.25	3.38	16.25	17.75	20-1.63	22	14.14		14.18	14	5.12	8.38	6.12	0.5	14.19	3.25
16	27.75	3.5	18.5	20	20-1.75	24.25	16.16		16.19	16	5.25	8.5	6.5	0.5	16.19	3.38
18	31	4	21	22.25	20-2.00	27	18.18		18.2	18	6	9	7.5	0.5	18.19	3.5
20	33.75	4.25	23	24.5	20-2.13	29.5	20.2		20.25	20	6.25	9.75	8.25	0.5	20.19	3.62
24	41	5.5	27.25	29.5	20-2.63	35.5	24.25		24.25	24	8	11.5	10.5	0.5	24.19	4
24	37	4	27.25	28.25	24-2.00	33	24.25	24.25	24	5.5	8	7.25	0.5	24.19	...	3.62

Dimensions are in inches.

(a)- Bolt hole diameter 1/8 in. larger than bolt diameter. (b)- Standard bore dimensions provided. See bore chart for other wall thicknesses. (c)- This dimension is commonly associated with "true" lap joints. Industry standard is to make to the slip on length through the hub.