Flange connection is a detachable connection, can be carried out in accordance with the different department of the connection, ensure the normal order of the flange connection. Flange with different classification criteria and classification, according to the connected components of the flange and pipe flange can be divided into the container. According to the structure, have integral flange, flange and thread. Large flange common integral flange are flat welding flange and butt welding flange. Flat welding flange of the poor rigidity, suitable for pressure p 4 mpa occasions or less; Butt welding flange is also called the high neck flange, large rigidity, suitable for the occasion of high pressure and temperature. There are three kinds of flange sealing surface model: planar seal face, is suitable for the occasion of pressure is not high, medium non-toxic; Concave-convex sealing surface, suitable for pressure slightly higher occasion; Grooved seal face, applicable to flammable, explosive, toxic medium and high pressure. Different flange pipe fittings in different fields have good product performance, to adapt to different occasions and space, the effect will be different. Ordinary rubber gasket is suitable for the occasion of temperature below 120 ℃; Asbestos rubber gasket suitable for vapor temperature below 450 ℃, the oil temperature is below 350 ℃, pressure is lower than 5 mpa, in a sort of corrosive medium, the most commonly used is acid-proof asbestos board. Large flange in high voltage equipment and pipelines, using 10 copper, aluminum, steel, stainless steel type lens or other shaped metal gasket. High pressure of large flange mat slice of contact with the sealing face width is very narrow, Line contact) With gasket sealing surface machining finish higher. Large flange gasket is a kind of can produce plastic deformation, and has certain strength rings made of materials. Most gaskets from non-metallic plate cutting down, or produced by professional factory in accordance with the provisions, the size, the material of asbestos rubber sheet, asbestos board, PE board, etc. ; Also useful thin metal plate ( Galvanized sheet, stainless steel) Will be made of asbestos etc. Nonmetal material wrapped metal package cushion; Another with steelskin belt with asbestos tape winding of spiral wound gasket. The large flange in use will produce different use value, has different functions and USES. The large flange material is qualitative different, production and processing process will be different, so the use and pay attention to the method when processing large flange, according to certain procedures and methods for use.