ASME/ANSI B16.5 Class 900 WN

The Welding neck flanges is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

The welding neck flange is the best designed butt-welded flange of those currently available because of its inherent structural value. It is expensive because of the design.

Nominal Pipe Size	Outside Diameter of Flange	Diameter of Raised Face	Thickness of Flanges Min.	Diameter of Hub	Hub Diameter Beginning of Chamfer	Length Through Hub	Bore	Diameter of Bolt Circle	Diameter of Bolt Holes	Number of Bolts	Approxi-mate Weight kgs
NPS	O	R	tf	X	A	Y	B	W	I	n
1/2	120	34.9	22.3	38	21.3	60	15.8	82.6	22.2	4	1.86
3/4	130	42.9	25.4	44	26.7	70	21.0	88.9	22.2	4	2.55
1	150	50.8	28.6	52	33.4	73	26.6	101.6	25.4	4	3.78
1 1/4	160	63.5	28.6	64	42.2	73	35.1	111.1	25.4	4	4.40
1 1/2	180	73.0	31.8	70	48.3	83	40.9	123.8	28.6	4	6.12
2	215	92.1	38.1	105	60.3	102	52.5	165.1	25.4	8	10.86
2 1/2	245	104.8	41.3	124	73.0	105	62.7	190.5	28.6	8	15.20
3	240	127.0	38.1	127	88.9	102	77.9	190.5	25.4	8	13.53
4	290	157.2	44.5	159	114.3	114	102.3	235.0	31.8	8	22.14
5	350	185.7	50.8	190	141.3	127	128.2	279.4	34.9	8	36.14
6	380	215.9	55.6	235	168.3	140	154.1	317.5	31.8	12	47.04
8	470	269.9	63.5	298	219.1	162	202.7	393.7	38.1	12	80.64
10	545	323.8	69.9	368	273.0	184	254.5	469.9	38.1	16	118.62
12	610	381.0	79.4	419	323.8	200	304.7	533.4	38.1	20	158.37
14	640	412.8	85.8	451	355.6	213	336.5	558.8	41.3	20	180.07
16	705	469.9	88.9	508	406.4	216	387.3	616.0	44.5	20	217.98
18	785	533.4	101.6	565	457.0	229	437.9	685.8	50.8	20	292.21
20	855	584.2	108.0	622	508.0	248	488.9	749.3	54.0	20	362.66
24	1040	692.2	139.7	749	610.0	292	590.9	901.7	66.7	20	665.98