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.
The flange above has 8 bolt holes, and a welding bevel of 37.5 degrees (red circle). All given dimensions are in millimeters. The raised face (RF) does not need to be specified, because according to ASME B16.5, each flange is standard delivered with a raised face. Only a different design (Ring Type Joint (RTJ), Flat Face (FF) etc.), should be specified.
The welding neck flange is the best designed butt-welded flange of those currently available becuase of its inherent structural value.
Expander Flange
Expander Flange is a Welding Neck pipe flange where the nominal size of the non-flanged end is larger than the nominal size of the flanged end. They can be used to change the size of a pipe run. These are usually used to increase the line size to the first or second larger size. This is an alternative to using a separate reducer and weld neck flange combination. The expander flange can be used to connect pipe to pumps, compressors and Valves.Long Weld Neck Flanges
Long Neck Welding (abbreviated LWN) flanges are similar to a standard Welding Neck flange, but the "Neck" is considerably longer.NW Long Weld Neck Flanges
The NW Long Weld 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.
Weldoflange, Nipoflange
The Weldoflange and Nipoflange is a combination of a Welding Neck flange and a supposedly Weldolet or Nipolet.
Standards, Dimensions & Weight of Welding Neck Flanges
WELDING NECK FLANGE NPS 6, CLASS 150, SCHEDULE 40, ASME B16.5 / ASTM A105
It is expensive because of the design.
- ASME/ANSI B16.5 Class 150 WN
- ASME/ANSI B16.5 Class 300 WN
- ASME/ANSI B16.5 Class 600 WN
- ASME/ANSI B16.5 Class 900 WN
- ASME/ANSI B16.5 Class 1500 WN
- ASME/ANSI B16.5 Class 2500 WN
- ASME B16.47 Series A/MSS SP-44 Class 150 WN
- ASME B16.47 Series A/MSS SP-44 Class 300 WN
- ASME B16.47 Series A/MSS SP-44 Class 600 WN
- ASME B16.47 Series A/MSS SP-44 Class 900 WN
- ASME B16.47 Series B/API 605 Class 75 WN
- ASME B16.47 Series B/API 605 Class 150 WN
- ASME B16.47 Series B/API 605 Class 300 WN
- ASME B16.47 Series B/API 605 Class 600 WN
- ASME B16.47 Series B/API 605 Class 900 WN
- BS 3293 Class 150 WN
- BS 3293 Class 300 WN
- BS 3293 Class 600 WN
- DIN 2631 PN 6
- DIN 2632 PN 10
- DIN 2633 PN 16
- DIN 2634 PN 25
- DIN 2635 PN40
Specifications of Welding Neck Flanges:
Size: 1/2” to 60”, DN 12mm to DN 1500mm
Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250
Facing: RF / RTJ
Material of Welding Neck Flanges:
Cabon steel: A105, A350 LF2, C22.8, S355JR
Stainless steel: A182 F304/F304L/F316/F316L/F321
Alloy steel: F11, F12
Packing: plywood case and plywood pallet
Temperature range
- Viton: -20°C to 200°C
- Silicone: -50°C to 230°C
- Buna: -30°C to 110°C
- EVAC metal seal: -270°C to 150°C
- Tube OD sizes: 3/8 to 2 inches
Materials:
- Flange: 304 or 316L stainless steel
- O-rings: Viton, Buna, & silicone
- Fasteners: Wingnut, SureSeal, bulkhead & EVAC clamps
Vacuum range
- Elastomer seal: >=1 x 10^-8 Torr - High vacuum
- EVAC metal seal: >=1 x 10^-11 Torr - UHV
