What is Weld Neck Flange?
Weld Neck Flange is a pipe fitting with a neck and a transition structure resembling a round tube, connected to pipelines via welding. It is primarily used in high-pressure, high-temperature, or media-sensitive piping systems. Its flared transition neck design keeps the weld away from the sealing face, minimizing welding deformation and enhancing sealing performance. It is suitable for pressure ratings ranging from PN2.5MPa to PN400 and higher standards.
The flange materials include carbon steel, stainless steel, nickel alloys, and over 20 other options. The manufacturing processes are categorized into forging, casting, cutting, and rolling. Forged flanges are preferred for high-stress applications due to their superior mechanical properties, while cast flanges are cost-effective for complex components. The products undergo quality control measures such as ultrasonic testing and post-weld heat treatment, complying with technical standards like those from the chemical industry (HG/T) and national standards (GB/T).
The flanges are marked by pressure ratings in DN-PN series (e.g., DN80-PN40) and feature six types of sealing faces, including raised face (RF) and male-female (MF) configurations, which are sealed with gaskets and bolted connections. They are widely used in industries such as oil, chemical, and power for valve and pipeline connections, particularly in applications involving flammable/explosive media or significant temperature fluctuations.
Specification of WN Flanges
Size: DN15-DN2000 (1/2-78 inch)
Surface Treatment: Anti-rust Oil, Transparent/Yellow/Black Anti-rust Paint,Zinc,Hot dipped Galvanized.
Weld Neck Flange Pressure Grade
PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN320, PN400
Class 150, Class 300, Class 600, Class 900, Class 1500, Class 2500
Weld Neck Flange Materials
Carbon Steel Flange: ASTM A105, 20#, Q235, 16Mn, ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2, ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65 ,F70;
Stainless Steel Flange: ASTM A182 F304, 304L, F316, 316L, 1Cr18Ni9Ti, 0Cr18Ni9Ti, 321, 18-8;
Alloy Steel Flange: ASTM A182 F1, F5a, F9, F11, F12, F22, F91, A182F12, A182F11, 16MnR, Cr5Mo, 12Cr1MoV, 15CrMo, 12Cr2Mo1, A335P22, St45.8/Ⅲ;
Sealing Surface Types For Weld Neck Flanges
RF (Raised Face);
FF (Flat Face);
M&F (Male-and-Female Face);
RTJ (Ring-Type Joint)
F (Female Face);
M (Male Face);
T&G (Tongue and Groove Face);
Among them, the uneven surface (MFM) is a matching use;
