A loose‑flange is a detachable flange plate, typically used in conjunction with plumbing and drainage fittings—most commonly on expansion joints. At the factory, each end of the expansion joint is fitted with a flange, which can be directly bolted to pipes and equipment on site. In essence, a loose‑flange combines two types of flanges. Common configurations include butt‑welded neck type, butt‑welded ring‑plate type, slip‑on ring‑plate type, and flanged ring‑plate type.

Loose 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, 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 slip‑on collar, typically used in piping systems. By loosening the bolts, the two pipe sections can be rotated relative to each other and then re‑tightened, enabling convenient disassembly and assembly of the pipeline. In a loose‑flange connection, the flange is slipped over the pipe end using a rolled edge or a steel ring, allowing the flange to slide along the pipe. The steel ring or rolled edge serves as the sealing surface, while the flange itself functions to compress and seal this interface. Consequently, because the steel ring or rolled edge acts as a barrier, the loose‑flange does not come into direct contact with the process medium.

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.