Flange classification

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1. Classified according to chemical industry standards: integral flanges (IF), threaded flanges (Th), plate slip-on flanges (PL), wafer flanges (WN), socket weld flanges (SO), socket weld and butt weld flanges (SW), butt weld ring loose flanges (PJ/SE), slip-on ring loose flanges (PJ/RJ), lined flange covers (BL(S)), and flange covers (BL). 2. Classified according to petrochemical industry standards: threaded flanges (PT), butt-welded flanges (WN), socket-welded flanges (SO), slip-welded flanges (SW), loose-flange types (LJ); flange covers (not specified). 3. Classified according to mechanical industry standards: integral flanges, butt-welded flanges, plate-type socket weld flanges, butt-welded ring plate-type loose flanges, plate-type socket weld ring plate-type loose flanges, flanged ring plate-type loose flanges, and flange covers. Flat weld steel flanges: Suitable for connecting carbon steel pipes with a nominal pressure not exceeding 2.5 MPa. The sealing surfaces of flat weld flanges can be designed in three types: smooth, ribbed, and keyway. Smooth flat weld flanges are the most widely used; they are employed in situations where the working conditions are relatively mild, such as low-pressure, unpurified compressed air or low-pressure circulating water. Their advantage is their relatively low cost ； Butt-welded steel flanges: Used for welding flanges to pipes; they have a rational structure, high strength and stiffness, can withstand high temperatures and pressures as well as repeated bending and temperature fluctuations, and offer reliable sealing. Butt-welded flanges with a nominal pressure of 0.25–2.5 MPa feature male-female type sealing surfaces. Socket-welded flanges: Commonly used in pipes with PN≤10.0 MPa and DN≤40 ； Loose-flange: Also known as a flexible flange, loose-flanges are divided into weld-ring type flexible flanges, flanged-type flexible flanges, and butt-welded flexible flanges. They are commonly used in situations where the temperature and pressure of the medium are not high, but the medium has strong corrosive properties. When the medium is highly corrosive, the part of the flange that comes into contact with the medium (the flanged stub) is made of corrosion-resistant high-grade materials such as stainless steel, while the outer portion is secured using lower-grade materials such as carbon steel flange rings to achieve sealing ； Integral flange: The flange is often integrated with equipment, pipes, fittings, valves, etc.; this type is commonly used on equipment and valves. Seal surface type: flat (FF), raised face (RF), male face (M), female face (F), mixed face (MF), tenon face (T), groove face (G), tenon-groove face (TG), ring joint face (RJ). The flange materials include: 20#, A105, Q235A, 12Cr1MoV, 16MnR, 15CrMo, 18-8, 321, 304, 304L, 316, 316L, etc. 4. Classified by **standard type: integral flanges, threaded flanges, butt-welded flanges, necked slip-on flanges, necked socket-welded flanges, butt-welded ring-necked loose flanges, plate-type slip-on flanges, butt-welded ring-plate loose flanges, slip-on ring-plate loose flanges, flanged ring-plate loose flanges, and flange covers.