Characteristics and structural shape of butt welding flange

　　Butt welding flange connection is the most basic and common connection mode in various vessels and process pipelines. Considering the requirements of production process or the convenience of manufacturing, transportation, installation and maintenance, the connection of vessel and process pipeline usually adopts detachable structure, i.e. butt welding flange connection, which has better connection strength and tightness, and has a wide range of applicable dimensions. Therefore, butt welding flange connection is widely used in vacuum salt manufacturing enterprises, because the medium of vessel and pipeline is to grasp Sodium chloride solution (i.e. brine) has strong corrosiveness. Although the carbon steel butt welding flange has high safety and good plasticity and cutting ability, its corrosion resistance is poor, and the corrosion phenomenon will appear in a large area after one month. A large area of perforation will appear in six months. Cause medium leakage. If the use of butt welding flange: first, the price is more expensive. The butt welding flange is about 3-5 times as much as the carbon steel butt welding flange; the second is that the welding technology is relatively higher, such as poor volatilization, which is easy to cause crack in the seam; the third is that the currently used butt welding flange will reduce the plasticity, toughness and stamping performance of the material due to the presence of titanium carbide in the steel. It is easy to break the butt welding flange if it is not used well.

　　F304 Pipe Fitting Forged Stainless Steel Weld Neck Flange is used to connect stainless steel valves. The butt welding flange is provided at both ends of the valve body, which corresponds to the butt welding flange on the pipeline. The butt welding flange is fixed by bolts and installed in the pipeline. Butt welding flange connection is the most widely used connection form in stainless steel valves. Butt welding flange can be divided into raised face (RF), flat face (FF), convex concave face (MF), etc. According to the shape of the joint surface, it can be divided into the following categories:

　　1) Smooth type: for stainless steel valves with low pressure. Easy to process

　　2) Concave convex type: high working pressure, medium hard washer can be used

　　3) Mortise and groove type: the washer with large plastic deformation can be used widely in corrosive medium, and the sealing effect is good.

　　4) Trapezoidal groove type: oval metal ring is used as gasket for valve with working pressure ≥ 64kg / cm2, or high temperature valve.

　　5) Lens type: gasket is lens shape, made of metal. For high pressure valve with working pressure ≥ 100kg / cm2, or high temperature valve.

　　6) O-ring type: This is a relatively new form of butt welding flange connection, which is developed with the emergence of various rubber O-rings.