Description of the use of various flanges

- Oct 03, 2020-

According to the current 4 standards in China, common flanges are basically: integral flange, butt welding flange, flat welding flange, threaded flange, socket welding flange and so on. So what should we choose flange and use?


(1) The nature of the conveying media, general media, special media, toxic media, flammable and explosive media;


(2) According to the parameters of the medium, working pressure and working temperature, when the medium is determined, the nominal pressure PN of the flange is determined according to the working temperature and working pressure of the medium.


(3) Determine the connection method and sealing surface form of the flange and the pipe according to the place of use and connection conditions.


(4) Determine the flange specifications according to the connection object.


Pipe flanges can be divided into five basic types according to the connection method with the pipe: flat welding flange, butt welding flange, threaded flange, socket welding flange, loose sleeve flange. There are many types of sealing surfaces of flanges. Generally, convex surface (RF), concave surface (FM), uneven surface (MFM), tongue and groove surface (TG), full plane (FF), ring connection surface (RJ) Welded flange.


Flat welded steel flange: suitable for connection of carbon steel pipes with a nominal pressure not exceeding 2.5MPa. The sealing surface of the flat welded flange can be made into three types: smooth, concave and convex and tongue and groove. Smooth flat welded flanges are the most widely used, and are mostly used when the media conditions are relatively mild, such as low-pressure non-purified compressed air and low-pressure circulating water. Its advantage is that the price is relatively cheap.


Butt-welded steel flange: used for butt welding of flange and pipe, its structure is reasonable, its strength and rigidity are large, it can withstand high temperature and high pressure, repeated bending and temperature fluctuation, and its sealing performance is reliable. The welding flange adopts concave and convex sealing surface.


Socket welding flange: commonly used in pipelines with PN≤10.0MPa and DN≤40.


Loose sleeve flange: Loose sleeve flange is commonly known as loose flange, divided welding ring loose flange, flanging loose flange and butt welded loose flange. It is commonly used for medium temperature and pressure are not high and the medium is corrosive Stronger situation. When the medium is highly corrosive, the part of the flange that contacts the medium (flanging short section) is a high-grade material such as stainless steel that is resistant to corrosion, and the outside is clamped by a flange ring of a low-grade material such as carbon steel To achieve sealing.


Integral flange: The flange is often integrated with equipment, pipes, fittings, valves, etc. This type is commonly used in equipment and valves.


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