Metric Dimensions of Weld Neck Flange Rating 300 as per ASME B16.5

NPS	O Flange OD	Ttf Thickness	X Hub Dia	A Hub Dia	Y Length	B Bore Dia
1/2	95	12.7	38	21.3	51	15.8
3/4	115	14.3	48	26.7	56	20.9
1	125	15.9	54	33.4	60	26.6
1-1/4	135	17.5	64	42.2	64	35.1
1-1/2	155	19.1	70	48.3	67	40.9
2	165	20.7	84	60.3	68	52.5
2-1/2	190	23.9	100	73	75	62.7
3	210	27	117	88.9	78	77.9
3-1/2	230	28.6	133	101.6	79	90.1
4	255	30.2	146	114.3	84	102.3
5	280	33.4	178	141.3	97	128.2
6	320	35	206	168.3	97	154.1
8	380	39.7	260	219.1	110	202.7
10	445	46.1	321	273	116	254.6
12	520	49.3	375	323.8	129	304.8
14	585	52.4	425	355.6	141	BY P
16	650	55.6	483	406.4	144	BY P
18	710	58.8	533	457	157	BY P
20	775	62	587	508	160	BY P
24	915	68.3	702	610	167	BY P

Templates for drilling of bolt holes

NPS	BCD	BHD	BOLTS	BD	SBL RFY	SBL RJ	MBL RF
1/2	66.7	5/8	4	1/2	65	75	55
3/4	82.6	3/4	4	5/8	75	90	65
1	88.9	3/4	4	5/8	75	90	65
1-1/4	98.4	3/4	4	5/8	85	95	70
1-1/2	114.3	7/8	4	3/4	90	100	75
2	127.0	3/4	8	5/8	90	100	75
2-1/2	149.2	7/8	8	3/4	100	115	85
3	168.3	7/8	8	3/4	110	120	90
3-1/2	184.2	7/8	8	3/4	110	125	95
4	200.0	7/8	8	3/4	115	125	95
5	235.0	7/8	8	3/4	120	135	110
6	269.9	7/8	12	3/4	120	140	110
8	330.2	1	12	7/8	140	150	120
10	387.4	1-1/8	16	1	160	170	140
12	450.8	1-1/4	16	1-1/8	170	185	145
14	514.4	1-1/4	20	1-1/8	180	190	160
16	571.5	1-3/8	20	1-1/4	190	205	165
18	628.6	1-3/8	24	1-1/4	195	210	170
20	685.8	1-3/8	24	1-1/4	205	220	185
24	812.8	1-5/8	24	1-1/2	230	255	205

Dimensions are in millimeters, except for diameters of bolts and bolt holes, which are in inch units.