Weld Neck Flange (WN)

On a high pressure, high temperature line — power plant steam piping, an oil & gas gathering header, a chemical process run or an offshore pipeline — the flange joint has to stay leak-tight through thermal cycling and severe vibration. The Weld Neck Flange (WN) is the highest integrity flange type, built for exactly these critical duties.

A Long Tapered Hub, Joined by Butt Welding

The WN flange has a long tapered hub and is connected to the pipe by butt welding. Its bore matches the pipe ID, forming a smooth transition between pipe and flange, so there is no abrupt change in flow path at the joint. Because the connection is a butt weld, the weld can be fully inspected by radiography.

• Long tapered hub, connected to pipe by butt welding
• Bore matches pipe ID, forming a smooth transition
• Butt weld can be fully inspected by radiography
• Tapered hub relieves stress concentration under pressure, temperature and vibration load
• Highest integrity flange type

Available Faces

WN flanges can be supplied with the following sealing faces to match the gasket and joint requirement of the line:

• RF — raised face
• FF — flat face
• RTJ — ring type joint
• MFM — male and female
• T&G — tongue and groove

Where It Is Used

The WN flange suits high pressure, high temperature, thermal cycling, severe vibration and critical service. Typical duties include oil & gas, power plant steam piping, chemical process, offshore pipeline and hazardous media.

Stress concentration under pressure, temperature and vibration load is relieved by the tapered hub — which is why the WN is the highest integrity flange type.

Applicable Standards

WN flanges are manufactured to the following dimensional and design standards: