Threaded Connection Flange

Flange is also called flange or flange.

The part that connects the pipe and the pipe to each other is connected to the end of the pipe. There are holes on the flanges, and bolts make the two flanges tightly connected. The flanges are sealed with gaskets. Flanged pipe fittings refer to pipe fittings with flanges (lugs or sockets). It can be made by casting (not shown in the picture), or it can be formed by threaded connection or welding. Flange connection (flange, joint) consists of a pair of flanges, a gasket and several bolts and nuts. The gasket is placed between the sealing surfaces of the two flanges. After tightening the nut, the specific pressure on the gasket surface reaches a certain value and deforms and fills up the unevenness of the sealing surface to make the connection tight and leak-proof. Flange connection is a detachable connection. According to the connected parts, it can be divided into container flange and pipe flange. According to the structure type, there are integral flanges, loose flanges and threaded flanges. Common integral flanges include flat welding flanges and butt welding flanges. Flat-welded flanges have poor rigidity and are suitable for occasions with pressure p≤4MPa; butt-welded flanges are also called high-neck flanges with greater rigidity and are suitable for occasions with higher pressure and temperature. There are three types of flange sealing surface: flat sealing surface, suitable for occasions with low pressure and non-toxic media; concave-convex sealing surface, suitable for occasions with slightly higher pressure; tongue and groove sealing surface, suitable for flammable and explosive , Toxic media and high pressure occasions. A gasket is a circular ring made of a material that can produce plastic deformation and has a certain strength. Most of the gaskets are cut from non-metallic plates, or made by professional factories according to the specified size. The materials are asbestos rubber plates, asbestos plates, polyethylene plates, etc.; thin metal plates (white iron, stainless steel) are also used to remove asbestos A metal-wrapped gasket made of non-metallic materials; there is also a spiral wound gasket made of thin steel tape and asbestos tape. Ordinary rubber gaskets are suitable for occasions where the temperature is lower than 120°C; asbestos rubber gaskets are suitable for occasions where the temperature of water vapor is lower than 450°C, the temperature of oil is lower than 350°C, and the pressure is lower than 5MPa, and it is generally corrosive. The most commonly used medium is acid-resistant asbestos board. In high-pressure equipment and pipelines, metal gaskets of lens type or other shapes made of copper, aluminum, No. 10 steel, and stainless steel are used. The contact width between the high-pressure gasket and the sealing surface is very narrow (line contact), and the processing finish of the sealing surface and the gasket is relatively high.

The flange is divided into threaded connection (wire connection) flange, welding flange and clamping flange. There are wire flanges and ferrule flanges for low-pressure small diameters. Welded flanges are used for high-pressure and low-pressure large diameters. The thickness of flanges and the diameter and number of connecting bolts are different for different pressures.