American Welding Neck Flange (WN Flange)
- Pipe diameter range: 1/2“~24” (NPS)
- Pressure Rating: Class150/300/600/900/1500/2500
- Applicable temperature: -50°C~200°C
- Standard: SA-105, SA-516 Gr.70
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American Welding Neck Flange (referred to as WN flange) is a kind of butt-welding flange with a neck, whose structure consists of a long conical neck (tapered hub) and flange forged as a whole, connected to the pipeline by means of Its structure consists of a long tapered hub and a flange, which is connected to the pipeline by BUTT WELD to ensure that the weld seam is the same as the wall thickness of the pipeline, which significantly improves the strength and sealing of the connection.
Welding Neck Flange Structure Details
Tapered Hub
Presenting a long tapered hub design with a taper range of 7° to 30°12 , the root thickness is 1.25 times the pipe wall thickness and more.
Neck height and pipe diameter are directly proportional to pressure class (e.g., NPS 6” Class 150 neck height is about 100 mm).
Flange Ring
The number of bolt holes matches the pipe diameter (e.g., 8 holes for NPS 6“ Class150, 20 holes for NPS 24” Class150).
The ASME B16.5 standard requires bolt hole centers (bolt circles) to be precisely spaced with a tight tolerance of ±0.8mm.
Butt Weld End
Standard bevel angle is 37.5°±2.5°34 , matching with pipe end bevel to ensure full penetration welding.
Bevel root clearance ≤1.6mm to prevent welding deformation.
Dimensional specifications: Follow ASME B16.5 (NPS 1/2“~24”) and B16.47 (NPS 26“~60”).
Material requirements: Forgings to meet SA-105/SA-182, plate to meet SA-516 (Class150~900).