A butt-welded flange is a type of pipe fitting; it is a flange with a neck and a cylindrical transition, which is welded to the pipe.

Welding Neck Flange

Seal face types: Flat Face (FF), Raised Face (RF), Male-Female (MFM), Tongue-and-Groove (TG), and Ring Joint (RJ)

Carbon Steel: 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: ASTM A182 F304, 304L, F316, 316L, 1Cr18Ni9Ti,

0Cr18Ni9Ti, 321, 18-8;

Alloy Steel: ASTM A182 F1, F5a, F9, F11, F12, F22, F91; A182F12; A182F11; 16MnR; Cr5Mo; 12Cr1MoV; 15CrMo; 12Cr2Mo1; A335P22; St45.8/Ⅲ;

Manufacturing Standards: ANSI B16.5, ANSI B16.47, HG20617-97, HG20595-97, GB/T9115-2000, GB10746-89, JB/T82.1-1994, CB/T47-1999, CBM1017-81, CBM1018-81, CBM1019-81

Connection method: single-sided welding, double-sided bolt-and-nut connection

Manufacturing process: integral forging or finished‑product forging and machining.

Manufacturing process: High-precision CNC lathe turning, CNC radial drilling.

Application scope: Welding‑neck flanges are resistant to deformation and provide excellent sealing, making them widely applicable. They are suitable for pipelines subject to significant pressure or temperature fluctuations, as well as for high‑temperature, high‑pressure, and cryogenic service. They are also used in piping systems conveying expensive, flammable, or explosive media.

Seal face types: Flat Face (FF), Raised Face (RF), Male-Female (MFM), Tongue-and-Groove (TG), and Ring Joint (RJ).

Carbon Steel: ASTM A105, 10#, 20#, Q235, Q345B, 16Mn, ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2, ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70

Stainless Steel: ASTM A182 F304, 304L, F316, 316L, 1Cr18Ni9Ti,

0Cr18Ni9Ti, 321, 18-8;

Alloy Steel: ASTM A182 F1, F5a, F9, F11, F12, F22, F91; A182F12; A182F11; 16MnR; Cr5Mo; 12Cr1MoV; 15CrMo; 12Cr2Mo1; A335P22; St45.8/Ⅲ;

Manufacturing standards: GB/T 9118-2000, HG 20599-97, HG 20600-97, HG 20621-97, GB/T 9120-2000, GB/T 9121-2000, JB/T 83-94, JB/T 84-94, GB 10747-89, CB/T 49-1999, CB/T 50-1999.

Connection method: single-sided welding, double-sided bolt-and-nut connection; the flange is rotatable and facilitates precise alignment of bolt holes.

Manufacturing process: integral forging or finished‑product forging and machining.

Manufacturing process: High-precision CNC lathe turning, CNC radial drilling.

Application scope: A loose‑flange is a flange equipped with a loose sleeve, typically used in piping systems. By loosening the bolts, the two pipe sections can be rotated relative to each other and then re‑tightened, allowing for convenient disassembly and assembly of the pipeline. In a loose‑flange connection, the flange is slipped over the pipe end using a collar or steel ring, enabling it to slide along the pipe. The steel ring or collar serves as the sealing surface, while the flange’s function is to compress and secure these components. Consequently, because the steel ring or collar acts as a barrier, the loose‑flange does not come into direct contact with the process medium.