Forged flanges are invented on the basis of cast steel flanges, and their strength is much higher than cast steel flanges, so that the parts connected with pipes are connected to the pipe end. Butt welding flange is a kind of pipe fitting, which refers to the flange with a neck and a round pipe transition and butt welding connection with the pipe. It is not easy to deformation, good sealing, widely used, suitable for pressure or temperature fluctuations of pipelines or high temperature, high pressure and low temperature pipelines, the advantage is cheaper, nominal pressure does not exceed 2.5mpa; It is also used for conveying expensive, flammable and explosive media on the pipeline, and the nominal pressure is about PN16MPa.
The forged flanges are perforated, and the bolts (consisting of head and screw) hold the two flanges together. The forged flanges are sealed with gaskets. Forged flanged pipe fittings refer to those with forged flanges (flanges or joints). It may be cast, threaded or welded. The flange connection consists of a pair of flanges, a gasket and a number of bolts and nuts. The gasket is placed between the sealing surfaces of two flanges, and after tightening the screw mother, the specific pressure on the surface of the gasket is deformed after reaching a certain value, and the uneven place on the sealing surface is filled, so that the connection is tight and leakproof.

There are three types of forging flange sealing surface: plane sealing surface, suitable for the pressure is not high, medium (decisive substance) non-toxic occasions; Concave and convex sealing surface, suitable for slightly higher pressure occasions; Sealing surface of tenon (S ǔ N) groove, suitable for flammable, explosive, toxic medium and high pressure occasions. Gasket is a ring made of Material that can produce plastic deformation and has a certain strength.
Most gaskets are cut down from non-metallic plates, or made by professional factories according to the specified size (GU ī ding), the Material is asbestos Rubber board, asbestos board, polyethylene board, etc. Also useful thin metal plate (iron sheet, stainless steel) asbestos and other non-metallic materials wrapped up made of metal gasket; There is also a kind of winding gasket made of thin steel belt and asbestos belt together. Flange is also called flange flange. The part that connects the pipe to the pipe is connected to the pipe end. There are holes in the flange and bolts hold the two flanges together. Gasket seals between flanges. Flange is a disk-shaped part, which is more common in pipeline engineering. Flanges are used in pairs.

In pipeline engineering, flange is mainly used for pipeline connection. At the end where two pipes need to be connected, install a flange for each. Wire flange can be used for low-pressure pipes, and welded flange can be used for pressure of more than 4 kg. Put a gasket between the two flannels and bolt them down. Flange manufacturers usually use bolts to connect the two planes in the periphery at the same time closed connection parts, generally known as "flange", such as ventilation pipe connection, this kind of parts can be called "flange parts". Ordinary rubber gasket is suitable for the occasion where the temperature is lower than 120 ℃; Asbestos rubber gasket is suitable for water vapor (referred to as water vapor) temperature is less than 450℃, oil temperature is less than 350℃, pressure is less than 5MPa occasions, for the general corrosive medium (play a decisive role in the material), more commonly used is acid resistant asbestos plate. In high pressure equipment (SHEBEI) and piping, metal gaskets of copper, aluminum (Al), no. 10 steel, stainless steel (stainless acid resistant steel) made of lens (classification: plastic lens and glass lens two kinds) or other shapes. The contact width of high-pressure gasket and sealing surface is very narrow (linear contact), and the processing finish of sealing surface and gasket is relatively high.