BS 3293 Class 150 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, O	Outside diameter, R	Thickness of flange min., C	Outside diameter of large end of hub, X	Outside diameter of small end of hub: Welding neck, A	Length through hub, Y	Fillet radius	Flange bore, B	Diameter of bolt circle, D	Diameter of bolt holes	Number of bolt holes
26	869.95	742.95	50.80	723.90	660.40	127.00	6.35	To be specified by the purchaser	806.45	34.93	24
28	927.10	793.75	52.39	781.05	711.20	128.59	6.35		863.60	34.93	28
30	984.25	857.25	53.98	831.85	762.00	130.18	6.35		914.40	34.93	28
32	1060.45	908.05	57.15	889.00	812.80	133.35	7.94		977.90	41.28	28
34	1111.25	958.85	58.74	939.80	863.60	134.94	7.94		1028.70	41.28	32
36	1168.40	1022.35	60.33	996.95	914.40	136.53	7.94		1085.85	41.28	32
38	1238.25	1073.15	60.33	1060.45	965.20	136.53	9.53		1149.35	41.28	32
40	1289.05	1123.95	63.50	1111.25	1016.00	139.70	9.53		1200.15	41.28	36
42	1346.20	1193.80	66.68	1168.40	1066.80	142.88	9.53		1257.30	41.28	36
44	1403.35	1244.60	66.68	1219.20	1117.60	142.88	11.11		1314.45	41.28	40
46	1454.15	1295.40	68.26	1270.00	1168.40	144.46	11.11		1365.25	41.28	40
48	1511.30	1358.90	69.85	1327.15	1219.20	146.05	11.11		1422.40	41.28	44