Slip On Pipe Flange VS Welding Neck Flange

Flat welding and butt welding are both the welding methods when the flange is connected to the pipe. Welding neck flange is a type of steel pipe welding neck flange, sometimes referred to as WN flange for short. It has a better sealing, has been widely used in high pressure and other pipelines or equipment instrumentation like valves, pumps, or other equipment,  for the field of chemical, petroleum, power industry and other where required high pressure, high temperature, flammable, explosive, toxic, harmful, toxic medium.

Flat welded flanges with neck, also referred to as slip-on welding flange, SO flange for short. SO flange and WN flange looks similar from their appearance and some people think they can be replaced, actually they according to with the same specification like ASME B16.5, ASME B16.47, ISO 7005-1-2011, BS 4504-3.1, DIN EN 1092-1 and so on. Today here we will introduce the difference between them.


SO and WN flange






In general, flat welding flanges are generally used for low and medium pressure pipelines, the butt-welding process is to reduce stress concentration and butt-welding flanges are used for the connection of medium and high-pressure pipelines, general butt-welding flanges are mostly with neck flanges, also called long neck flanges.