Valve design and selection of the key must be considered in one of the problems is the operating temperature of the valve. In order to standardize the valve body material suitable operating temperature, from various types of valve steel and alloy grade material properties of China's petrochemical, chemical, fertilizer, electric power and metallurgy industry, the appropriate operating temperature of the valve body materials and related requirements made clear provisions for valve product design, manufacture and inspection.   

    In addition, from the technical management and production management and material procurement considerations, for each type of steel should be selected comprehensive performance is good, it is inappropriate to choose too many steel and alloy grades, in order to prevent confusion.

    1. Overview Valve design and selection of the key must be considered in one of the problems is the operating temperature of the valve. In order to standardize the valve body material suitable operating temperature, from various types of valve steel and alloy grade material properties of China's petrochemical, chemical, fertilizer, electric power and metallurgy industry, the appropriate operating temperature of the valve body materials and related requirements made clear provisions for valve product design, manufacture and inspection.

  In addition, from the technical management and production management and material procurement considerations, for each type of steel should be selected comprehensive performance is good, it is inappropriate to choose too many steel and alloy grades, in order to prevent confusion.

    2. Low temperature Working condition

    2.1 Ultra-low temperature valve material   

    Ultra-Low temperature valve (-254 (liquid hydrogen) ~-101℃ (ethylene) Main material must choose austenitic stainless steel, copper alloy or aluminum alloy of the surface core cubic lattice, the low-temperature mechanical properties of the heat treatment, especially the low-temperature impact toughness must meet the standard requirements. The following austenitic stainless steels can be used to manufacture ultra-low temperature valves. ASTM A351 cf8m, cf3m, CF8 and cf3,astm A182 F316, f316l, F304 and f304l,astm A433 316, 316L, 304, 304L and cf8d (Lanzhou High pressure valve factory design, Factory standard Code gfq81-93).

    Cryogenic valve body, bonnet, gate or disc, etc. before finishing, must be in liquid nitrogen ( -196℃) for cryogenic treatment.

    2.2 Cryogenic valve Material   

    The main materials suitable for cryogenic valves ( -100~-30℃) are ferritic and martensitic steels for cryogenic austenitic stainless steels and cryogenic pressure parts.   

    Austenitic stainless steels for cryogenic use are ASTM A351 cf8m, cf3m, CF8 and cf3,astm A182 F316, f316l, F304 and f304l,astm A433 316, 316L, 304, 304L and cf8d.   

    Ferritic and martensitic steels for cryogenic pressure-bearing parts are ASTM A352 LCA ( -32℃), LCB, LCC ( -46℃), LC1 ( -59℃), LC2, LC211 ( -73℃) and LC3 ( -100℃). ASTM A352 standards of materials in the lower primary price, but the smelting of the chemical composition must have a reliable and demanding strict plant control standards. Its heat treatment process is complex and needs to be adjusted several times to meet the standard requirements of low-temperature impact toughness, long production cycle. When the low temperature impact toughness is not up to the standard, it is not allowed to be used for low-temperature steel. 

    Therefore, only in the production of large quantities, and can be used in furnace smelting, and in general, the selection of austenitic stainless steel.

    3. Non-corrosive working condition Valve working medium for water, steam, air and oil and other non-corrosive substances, the general use of carbon steel. Carbon steel for valves refers to WCB, WCC cast Steel and ASTM A105 forged steels in ASTM A216 standards. The suitable working temperature of carbon steel for valve is-29~425℃. However, in order to be safe, considering that the working temperature of the medium may fluctuate, the general carbon steel should not be used for more than 400 ℃.