Scope of application of valve body material, working temperature and pressure range of valve material

When selecting the valve body material for a valve, it is necessary to determine the valve body material suitable for the working conditions based on different applications and pressure levels. 1、 Valves are classified by valve body material. 1. Metal material valves: their valve body and other parts are made of metal materials. Such as cast iron valves, carbon steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc. 2. Non metallic material valve: Its valve body and other parts are made of non-metallic materials. Such as plastic valves, ceramic valves, and enamel valves; Valves, fiberglass valves, etc. 3. Metal lined valve body: The valve body is made of metal, and all major surfaces that come into contact with the medium inside are lined, such as rubber lined valves, plastic lined valves, ceramic lined valves, etc. 2、 Common materials for valve bodies and analysis of heat treatment of various materials. There are many types of valve body materials that are suitable for different working conditions.   1. Gray cast iron, suitable for low-pressure valves with a working temperature between -15~+200 ℃ and a nominal pressure PN ≤ 1.6MPa. 2. Blackheart malleable cast iron, suitable for medium and low pressure valves with a working temperature between -15~+250 ℃ and a nominal pressure PN ≤ 2.5MPa. 3. Ductile iron, suitable for medium and low pressure valves with a working temperature between -30~+350 ℃ and a nominal pressure PN ≤ 4.0MPa. 4. Carbon steel (WCA, WCB, WCC) is suitable for medium and high pressure valves with working temperatures between -29~+425 ℃. Among them, 16Mn and 30Mn have working temperatures between -40~+450 ℃ and are commonly used to replace ASTMA105. 5. Low temperature carbon steel (LCB) is suitable for low-temperature valves and valves with operating temperatures between -46~+345 ℃. 6. Alloy steel (WC6, WC9), suitable for high temperature and high pressure valves in non corrosive media with working temperatures between -29~+595 ℃; WC5 and WC12 are suitable for high temperature and high pressure valves for corrosive media with working temperatures between -29~+650 ℃. 7. Austenitic stainless steel, suitable for valves in corrosive media with working temperatures between -196~+600 ℃. 8. Monel alloy is mainly suitable for valves containing hydrogen fluorine media. 9. Cast copper alloy is mainly suitable for valves used in oxygen pipelines with working temperatures between -273~+200 ℃. The above are the major categories of commonly used materials for valve bodies, and there are many different grades for each type of material, which are suitable for various pressure levels. Therefore, when selecting the valve body material for a valve, it is necessary to determine the valve body material suitable for the working conditions based on different applications and pressure levels. In addition, valve body materials include titanium alloy (titanium valve) and aluminum alloy (aluminum valve); Plastic (plastic valve); Ceramics (ceramic valves) and so on. 3、 Heat treatment process for valve body blank 1. Heat treatment of gray cast iron: In order to achieve different goals, gray cast iron can undergo different heat treatments after casting. The commonly used heat treatment processes for gray cast iron valve bodies and other parts in valve production after casting include thermal aging to eliminate casting stress and high-temperature annealing to eliminate free carbides. Thermal aging is a necessary process. High temperature annealing is only used to replace thermal aging when there is a presence of primary carbides in the microstructure after casting due to improper control of chemical composition and casting cooling rate during casting. 2. Heat treatment of carbon cast steel: Cast steel parts have significant casting residual stress after casting, and sometimes the structure of the cast steel parts is coarse, and even overheated structure appears. These all affect the dimensional stability of cast steel parts, reduce the mechanical properties of steel, and are not conducive to cutting operations. In order to eliminate casting stress, refine structure, improve mechanical properties, and enhance machinability, carbon steel valve bodies and other parts are often treated with annealing or normalizing+tempering after casting in valve production. 3. Heat treatment of austenitic stainless acid resistant steel: The main defect of austenitic stainless acid resistant steel is that it is prone to intergranular corrosion. Generally, preventive measures can be taken by applying certain heat treatment to the steel. The commonly used heat treatment processes for valve bodies and other parts made of austenitic stainless acid resistant steel in valve production include solution treatment (quenching), stabilization treatment, and cryogenic treatment. 4. Heat treatment of martensitic heat-resistant steel: martensitic heat-resistant steel should be annealed in a timely manner after casting to prevent cracking, and the annealing and insulation time should be sufficient (generally 4-8 hours). The purpose of annealing martensitic heat-resistant steel is to eliminate stress, carry out recrystallization, refine grain size, reduce hardness, improve cutting performance, and prepare the microstructure for final heat treatment. The final heat treatment of martensitic heat-resistant steel adopts normalizing+tempering treatment. 5. Heat treatment of high-quality carbon steel: Taking the forged 35 steel valve body as an example, the 35 steel valve body needs to be normalized after forging, and its final heat treatment should be carried out according to the regulations of the valve manufacturing technical documents, generally requiring quenching and tempering treatment. 4、 The application scope of valve materials listed above is a major category of commonly used materials for valve bodies. There are many different grades for each type of material, which are suitable for various pressure levels. Therefore, when selecting the valve body material for a valve, it is necessary to determine the suitable application range of valve materials according to different purposes and pressure levels. Table: WCB Carbon Steel ASTM; A216 Non corrosive applications, including water, oil, and gas, temperature range: -30oC to+425oC; LCB Low Temperature Carbon Steel ASTM; A352 low temperature application, with temperatures as low as -46oC; Cannot be used in situations where the temperature is above+340oC; LC33.5% Nickel Steel ASTM; A352 low temperature application, temperature as low as -101oC  Cannot be used in situations where the temperature is above+340oC; WC61.25% chromium 0.5% molybdenum steel ASTM  A217 Non corrosive applications, including water, oil, and gas, temperature range: -30oC to+593oC; WC92.25 Chromium ASTM; A217 Non corrosive applications, including water, oil grade WC9 and gas, temperature range: -30oC to+593oC; C55% chromium 0.5% molybdenum ASTM; A217 Mild corrosive or erosive applications and non corrosive applications, temperature range: -30oC to+649oC; C129% chromium and 1% molybdenum ASTM; A217 Mild corrosive or erosive applications and non corrosive applications, temperature range: -30oC to+649oC; CA6NM (4) 12% Chromium Steel ASTM  A487 Corrosive application, temperature range: -30oC to+482OC; CA15 (4) 12% chromium ASTM; A217 Corrosive Application,  Temperature range up to+704oC; CF8M  316 stainless steel ASTM; A351 corrosive or ultra-low temperature or high temperature non corrosive applications, temperature range: -268oC to+649oC,  CF8C347 stainless steel ASTM; A351 is mainly used for high temperature, corrosive applications, temperature range: -268oC to+649oC, CF8304 stainless steel ASTM  A351 corrosive or ultra-low temperature or high temperature non corrosive applications, temperature range: -268oC to+649oC, CF3304L stainless steel ASTM  A351 corrosive or non corrosive applications;     Temperature range up to+425oC; Note: CF8M is equivalent to ZG0Cr17Ni12Mo2 in China, corresponding to a profile of 316 stainless steel, corrosive or ultra-low temperature or high temperature non corrosive applications, temperature range: -268 ℃ to+649 ℃, temperature above+425 ℃ requires a specified carbon content of 0.04% or above. CF8 is equivalent to ZG0Cr18Ni9 in China, corresponding to a profile of 304 stainless steel, corrosive or ultra-low temperature or high temperature non corrosive applications, temperature range: -268 ℃ to+649 ℃, temperature above+425 ℃ requires a specified carbon content of 0.04% or above. WCB is a US cast steel grade, medium carbon steel, non corrosive applications, including water, oil and gas, temperature range: -30 ℃ to 425 ℃ HT200. Chinese gray cast iron grade 1000WOG, 1000 refers to 1000PSI (approximately 68.94 kilograms), WOG is the English letters for water, oil, and gas.