Weld Neck Flange

A weld neck flange (also known as a high-hub flange and tapered hub flange) is a type of flange. There are two designs. The regular type is used with pipes. The long type is unsuitable for pipes and is used in process plant. A weld neck flange consists of a circular fitting with a protruding rim around the circumference. Generally machined from a forging, these flanges are typically butt welded to a pipe. The rim has a series of drilled holes that permit the flange to be affixed to another flange with bolts.

Such flanges are suitable for use in hostile environments that have extremes of temperature, pressure or other sources of stress. The resilience of this type of flange is achieved by sharing the environmental stress with the pipe with which it is welded. This type of flange has been used successfully at pressures up to 5,000 psi.

Long Weld Neck Flange

Long WN flange looks like the typical welding neck flange, but is considered to be elongated. It’s usually used as a nozzle for a column or barrel. You can also choose between the Equal LWN Barrel and LWN Heavy Barrel, which have a thick wall and their own shape.

Reducing Weld Neck Flange

It is also called reducing welding neck flange, because the flange neck has a reducing diameter that to weld to a smaller diameter pipe.

Standards Referred for Weld Neck Flange

Material Standards

ASTM A105/N For carbon steel weld neck flange

ASTM A182 F11, F22 for alloy steel

ASTM A182 F304 / F304L, F316 / F316L for stainless steel weld neck flange.

Manufacturing Standards

ASME B16.5

ASME B16.47

BS 3293

DIN 2630 PN 1 and PN 2.5, 2631 PN 6, 2632 PN 10, 2634 PN 16, 2634 PN 25, 2635 PN 40

Weld Neck Flange Dimensions

ASME B16.5-2020 Pipe Flanges and  Flanged Fittings NPS ½ Through NPS 24  Metric/Inch Standard

CLASS 150、CLASS 300、CLASS 400、CLASS 600、CLASS 900、CLASS 1500、CLASS 2500