What is a flange? What is this for?

Flange connects the parts of the pipeline to the end of the pipeline. There are holes in the flanges, and bolts make the two flanges closely connected. The flange is sealed with a gasket. Flanged pipe fittings refer to pipe fittings with flanges (flanges or flanges). It can be cast (missing in the figure), threaded or welded. Flange (joint) consists of a pair of flanges, a gasket and several bolts and nuts. The gasket is placed between the sealing surfaces of two flanges. After the nut is tightened, the specific pressure on the gasket surface will be deformed after reaching a certain value, and the uneven part on the sealing surface will be filled to make the connection tight. Flange connection is a detachable connection. According to the connection parts, it can be divided into container flange and pipeline flange. According to the structure type, there are integral flange, loose sleeve flange and threaded flange. Common integral flanges are flat welded flanges and welded flanges. Flat welding flange has poor rigidity, which is suitable for situations where the pressure p is less than or equal to 4 MPa. Welding flange, also known as high neck flange, has high rigidity and is suitable for occasions with high pressure and temperature. There are three kinds of flange sealing surfaces: plane sealing surface, which is suitable for occasions with low pressure and non-toxic medium; Concave-convex sealing surface, suitable for occasions with slightly higher pressure; The tenon-groove sealing surface is suitable for flammable, explosive and toxic media and high-pressure occasions. The gasket is a circular ring made of plastic deformation and certain strength. Most gaskets are cut from nonmetallic plates or made by professional factories according to the specified size, and their materials are asbestos rubber plates, asbestos plates, polyethylene plates and so on. There are also metal-clad gaskets made of non-metallic materials such as asbestos wrapped with thin metal plates (iron sheets and stainless steel); There is also a kind of wound gasket, which is made of thin steel strip and asbestos strip. Ordinary rubber gasket is suitable for occasions where the temperature is lower than 120℃; Asbestos rubber gasket is suitable for occasions with steam temperature below 450℃, oil temperature below 350℃ and pressure below 5MPa. For general corrosive media, the most commonly used is acid-resistant asbestos board. Lens-shaped or other metal gaskets made of copper, aluminum, 10 steel and stainless steel are used in high-voltage equipment and pipelines. The contact width between high-pressure gasket and sealing surface is very narrow (line contact), and the machining smoothness between sealing surface and gasket is high. Flanges are divided into threaded (threaded) flanges and welded flanges. Threaded connection flanges are used for small diameter low pressure, and welded flanges are used for large diameter high pressure and low pressure. Under different pressures, the thickness of flange and the diameter and number of connecting bolts are different. According to different pressure grades, flange pads are made of different materials, ranging from low-pressure asbestos pads, high-pressure asbestos pads to metal pads. 1. Carbon steel, cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, argon, ppc, etc. 2. According to the manufacturing method, it can be divided into forged flange, cast flange, welded flange and rolled flange (extra large). 3. According to the manufacturing standard, it can be divided into national standard (Ministry of Chemical Industry standard, petroleum standard and electric power standard), American standard, German standard, Japanese standard and Russian standard. Several systems of international pipeline flange standards, 1, flange connection or flange joint, refer to a set of combined sealing structure composed of flanges, gaskets and bolts. Pipeline flange refers to the flange used for pipeline in pipeline device, and refers to the import and export flange of equipment when used on equipment. 2. Several systems of international pipeline flange standards 1) European flange systems: DIN (including Soviet Union), BS, NF, UNI a, nominal pressure: 0. 1, 0.25, 0.6, 1.0, 1.6, 2. 16.0, 25.0, 32.0, 40.0 Mpa b, calculated diameter:15 ~ 4,000 mm (the maximum diameter varies with the selected flange specification and flange pressure level) C. Structural types of flanges: flat welded plate, flat welded ring loose sleeve, loose sleeve of rolled edge and loose sleeve of butt welded ring. The recording standard of OCT pipe flange issued by the lens surface and diaphragm welding surface E and the Soviet Union 1980 is similar to the German DIN standard, and will not be repeated here. 2) American flange system: American ANSI B 16.5 Steel Pipe Flanges and Flanged Fittings ANSI B 16.47A/B Large Diameter Steel Flanges B65438+. A. nominal pressures: 150psi(2.0Mpa), 300psi(5.0Mpa), 400psi(6.8Mpa), 600psi( 10.0Mpa), 900psi( 15.0Mpa) and/kloc. B, calculated diameter: 6~4000mm c, flange structure type: belt welding, socket welding, threaded connection, loose sleeve, butt welding, flange cover D, flange sealing surface: concave surface, concave-convex surface, mortise surface and metal ring connection surface 3) ***JIS pipe flange: generally only used for public works in petrochemical plants, with little international influence and not yet formed internationally. 3. Chinese national standard system GB 1) Nominal pressure: 0.25mpa ~ 42.0mpa, series 1: PN 1.0, PN 1.6, PN 2.0, PN 5.0, pn10. PN42 (main series) B and series 2: 2:PN0.25, PN0.6, PN2.5 and PN4.0, among which six levels of flange sizes are PN0.25, PN0.6, PnKloc-0/.0, Pn01.6, PN2.5 and Pn4.0. In GB standard, the maximum nominal pressure rating of European flange system is 4Mpa, and that of American flange system is 42Mpa. 2) Nominal diameter: 10mm~4000mm 3) Flange structure: integral flange unit flange A, threaded flange B, welding flange neck flat welding flange neck socket welding flange plate flat welding flange C, loose sleeve flange butt welding ring loose sleeve neck flange flat welding ring loose sleeve flange plate turnover loose sleeve flange D, flange cover (blind hole flange) E, rotating flange F, anchor flange G, surfacing welding. Piping flange standard system commonly used in instruments, d in standard 1) Common pressure grades: PN25, PN405438+00. PN 100, PN 160, PN250 2) Flange sealing surface: convex DIN2526C convex flange polished ACC. DIN 25 12n mortise surface 2, ANSI standard 1) Common pressure grades: CL 150, CL300, CL. CL900, CL 1500 2) flange sealing surface: ANSI B 16.5 RF flange 3. JIS standard: not commonly used 1) Common pressure rating: 10K 20K flange connection type plate flat welding neck flange flat welding neck flange socket welding flange threaded flange cover flat welding ring loose sleeve flange flat welding ring loose sleeve flange groove surface flange and flange cover large diameter flat flange large diameter high neck flange splayed butt welding ring loose sleeve flange anchoring flange anchoring flange surfacing welding/cover welding flange connecting flange (flange). Some pipe fittings and equipment have their own flanges, which are also flange connections. Flange connection is an important connection mode in pipeline construction. Flange connection is easy to use and can withstand greater pressure. Flange connection is widely used in industrial pipelines. At home, the pipe diameter is small and the pressure is low, so the flange connection is invisible. If you are in the boiler room or production site, there are flanged pipes and equipment everywhere.