Weld neck flange

What is weld neck flange?

Weld neck flange is a kind of pipe fitting which refers to a flange with a neck and a round pipe transition and connected with the pipe butt welding.

There are two designs. The regular type is suitable for pipes. Long type not suitable for piping, for processing plants.

Materials of WN Flanges:

WN flanges are suitable for various materials. These materials must conform to the standards set and also should be produce as per the quality specified by the ASTM or ASME standards.

However, the thickness and inner diameter of the flange will depend on the size of the pipe from which the welded neck flange is made.

Carbon steel and alloy steel are commonly used for WN flanges because of their resistance to extreme temperatures.  It is available in materials of ASTM A 181, and ASTM A 105. In addition, they are also made of stainless steel. Such as ASTM A182, F304, 316L, 347H, 310S, ASME B16 5, and more.

Common production standards:

Ministry of Chemical Industry standard	HG/T20592-2009, HG/T20615-2009
National standard	GB/T9115.1-2000, GB/T9115.2-2000, GB/T9115.3-2000, GB/T9115.4-2000
Mechanical department standard	JB/T86.2-94
Marine standard	CB/T47-1999

Sealing surface forms of weld neck flange are:

Convex surface (RF), concave surface (FM), convex surface (M), tenon surface (T), groove surface (G), full plane (FF).

Application Scope:

Weld neck flange is not easy to deform, good sealing, widely used, there are corresponding rigid and elastic requirements and reasonable butt welding thinning transition, welding from the joint surface distance is large, joint surface from welding temperature deformation.

It takes a more complex shape structure, suitable for pressure or temperature fluctuation pipeline or high temperature, high pressure and low temperature pipeline, generally used for PN greater than 2.5MPa pipeline and valve connection; It is also used for conveying expensive, flammable and explosive media on the pipeline.

advantages and disadvantages of the weld neck flanges:

Advantages

• Not easy to deform of the connection
• Good sealing effect
• Wide application

Disadvantages

• Bulky, heavy, expensive
• Difficult to install and locate
• More likely to knock during transportation