Guidance for the use of temperature and medium of commonly used materials for valves

One of the key issues that must be considered during valve design and material selection is the valve's operating temperature. In order to standardize the suitable working temperature of the valve body material, the suitable working temperature and related aspects of the valve body materials used in the petrochemical, chemical, fertilizer, electric power and metallurgical industries in my country from the material performance of various types of valve steel and alloy grades The requirements have made clear regulations for the design, manufacture and inspection of valve products. In addition, considering the aspects of technical management, production management and material procurement, each type of steel should be selected with good comprehensive performance, and it is not advisable to use too many steel grades and alloy grades to prevent confusion.

Introduction of suitable working temperature of valve main parts:

1、Overview

One of the key issues that must be considered during valve design and material selection is the valve's operating temperature. In order to standardize the suitable working temperature of the valve body material, the suitable working temperature and related aspects of the valve body materials used in the petrochemical, chemical, fertilizer, electric power and metallurgical industries in my country from the material performance of various types of valve steel and alloy grades The requirements have made clear regulations for the design, manufacture and inspection of valve products. In addition, considering the aspects of technical management, production management and material procurement, each type of steel should be selected with good comprehensive performance, and it is not advisable to use too many steel grades and alloy grades to prevent confusion.

2. Low temperature conditions

2.1 Ultra-low temperature valve materials

Ultra-low temperature valve [-254(liquid hydrogen)～-101℃(ethylene)] The main material must be austenitic stainless steel, copper alloy or aluminum alloy with face-centered cubic lattice, and its low-temperature mechanical properties after heat treatment, especially low-temperature impact Resilience 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. The body, bonnet, gate or disc of the ultra-low temperature valve must be cryogenically treated in liquid nitrogen (-196℃) before finishing.

2.2 Cryogenic valve materials

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

     Low-temperature austenitic stainless steels include 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 low-temperature pressure-bearing parts include ASTM A352 LCA(-32℃), LCB, LCC(-46℃), LC1(-59℃), LC2, LC211(-73℃) and LC3( -100°C).

       The material in the ASTM A352 standard has a lower primary price, but its chemical composition during smelting must have reliable and very strict factory internal control standards. The heat treatment process is complicated and requires multiple quenching and tempering treatments to meet the requirements of low-temperature impact toughness required by the standard, and the production cycle is long. When the low-temperature impact toughness does not meet the standard requirements, it is not allowed to be used as low-temperature steel. Therefore, it is only used when the production batch is large and can be smelted in a furnace, and in general, austenitic stainless steel is used.