Ordinary flanges and valves generally do not require heat treatment. But sometimes, when they have strength, hardness, rust resistance and other requirements, heat treatment is required. 

 Heat treatment refers to a metal thermal processing process that obtains the expected structure and performance of a material in a solid state by means of heating, heat preservation and cooling. 

 The valve is a control component in the fluid transmission system, with the functions of cut-off, adjustment, diversion, prevention of countercurrent, voltage stabilization, shunt or overflow pressure relief. 

 Valves for fluid control systems, from the simplest cut-off valves to various valves used in extremely complex automatic control systems, have a wide variety of varieties and specifications. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metals and radioactive media. According to the material, the valve is also divided into cast iron valve, cast steel valve, stainless steel valve (201, 304, 316, etc.), chromium molybdenum steel valve, chromium molybdenum vanadium steel valve, dual-phase steel valve, plastic valve, non-standard customized and other valve materials.