The Cryogenic and Non-corrosive Working Conditions of Valves
The working temperature of the valve is one of the aspects of great significance which must be considered in the design and selecting materials of valves. In order to standardize the appropriate working temperature of the valves' main body materials, specifications have been made on the main body materials' working temperature and other relative requirements of valves used in the petrochemical, chemical and metallurgical industries, depending on the performance of various materials such as steel and alloy with different grades. These specifications must be paid great attention to when the valve is designed, manufactured and inspected. In addition, from the perspectives of material procurement, technology and production management, the valve should be made of steel with superior comprehensive performance, and a valve should not be made of too many grades of steel and alloy to avoid causing confusion.
The super cryogenic valve must be made of austenitic stainless steel, copper alloy or aluminum alloy in the face-centered cubic lattice. After the heat treatment, valves' low temperature mechanical properties, especially the low temperature impact toughness must meet the requirements of the relevant standards. The valve body, the valve bonnet and the valve clack of the super cryogenic valve must have the cryogenic treatment in the liquid nitrogen of -196℃ before the finish machining.
The super cryogenic valve can be made of various kinds of austenitic stainless steel such as ASTM A351 CF8M, CF3M, CF8, CF3 and ASTM A182 F316, F316L, F304, F304L.
The main material of the cryogenic valve is austenitic stainless steel, such as ASTM A351 CF8M, CF3M, CF8, CF3 and ASTM A182 F316, F316L, F304, F304L, and the cryogenic bearing parts can be made of ferrite and martensitic steel such as ASTM A352 LCA(-32℃), LCB, LCC(-46℃), LC1(-59℃), LC2, LC211(-73℃) and LC3(-100℃).
ASTM A352 steel has the relatively lower primary price, but its chemical composition must be reliably and strictly controlled according to the inner quality standards of each manufacturer in the smelting process. The valves made of the ASTM A352 steel have long production cycles as well as complex heat treatment processes, and they need to have the repeated quenching treatment and tempering treatment so that the low temperature impact toughness of the ASTM A352 steel can meet the requirements of the standards. When the ASTM A352 steel has the low temperature impact toughness which can not meet the standard requirements, it is not allowed to use the ASTM A352 steel as the low temperature steel. Therefore, the ASTM A352 steel is only used when it is the large batch production, and the general choice is the austenitic stainless steel.
The valves which are used to transport the non-corrosive substances such as water, steam, air and oil are usually made of carbon steel, which refers to the WCB and the WCC cast steel of the ASTM A216 standard as well as the forged steel of the ASTM A105.
The working temperature of the carbon steel for valves is between -29℃ and 425℃. However, for the sake of safety, considering that the operating temperature of the media may fluctuate, the general working temperature of the carbon steel should not exceed 400℃.
The super cryogenic valve must be made of austenitic stainless steel, copper alloy or aluminum alloy in the face-centered cubic lattice. After the heat treatment, valves' low temperature mechanical properties, especially the low temperature impact toughness must meet the requirements of the relevant standards. The valve body, the valve bonnet and the valve clack of the super cryogenic valve must have the cryogenic treatment in the liquid nitrogen of -196℃ before the finish machining.
The super cryogenic valve can be made of various kinds of austenitic stainless steel such as ASTM A351 CF8M, CF3M, CF8, CF3 and ASTM A182 F316, F316L, F304, F304L.
The main material of the cryogenic valve is austenitic stainless steel, such as ASTM A351 CF8M, CF3M, CF8, CF3 and ASTM A182 F316, F316L, F304, F304L, and the cryogenic bearing parts can be made of ferrite and martensitic steel such as ASTM A352 LCA(-32℃), LCB, LCC(-46℃), LC1(-59℃), LC2, LC211(-73℃) and LC3(-100℃).
ASTM A352 steel has the relatively lower primary price, but its chemical composition must be reliably and strictly controlled according to the inner quality standards of each manufacturer in the smelting process. The valves made of the ASTM A352 steel have long production cycles as well as complex heat treatment processes, and they need to have the repeated quenching treatment and tempering treatment so that the low temperature impact toughness of the ASTM A352 steel can meet the requirements of the standards. When the ASTM A352 steel has the low temperature impact toughness which can not meet the standard requirements, it is not allowed to use the ASTM A352 steel as the low temperature steel. Therefore, the ASTM A352 steel is only used when it is the large batch production, and the general choice is the austenitic stainless steel.
The valves which are used to transport the non-corrosive substances such as water, steam, air and oil are usually made of carbon steel, which refers to the WCB and the WCC cast steel of the ASTM A216 standard as well as the forged steel of the ASTM A105.
The working temperature of the carbon steel for valves is between -29℃ and 425℃. However, for the sake of safety, considering that the operating temperature of the media may fluctuate, the general working temperature of the carbon steel should not exceed 400℃.
