Valve body material representation
4. carbon steels (WCA, WCB, WCC) originally developed for steel to meet the production needs beyond those of cast iron valves and bronze valves. But due to the use of the good performance of carbon steel valve, and the resistance strength stress on by thermal expansion, impact load and deformation of pipeline, makes its use scope, usually including the use of cast steel valves and bronze valve operating conditions.It is suitable for middle and high pressure valves whose operating temperature is between - 29~425. Among them, 16Mn and 30Mn are used as the temperature between 40~400 and A105, which is often used instead of ASTM. Applicable medium is saturated steam and superheated steam. High temperature and low temperature oil, liquefied gas, compressed air, water, gas and so on.5. low temperature carbon steel (LCB) low carbon steel and low nickel alloy steel can be used below zero temperature range, but can not be expanded to use in cryogenic zone. Valves made of these materials are suitable for the following medium, such as seawater, carbon dioxide, acetylene, propylene and ethylene.Low temperature valve suitable for operating temperature between 46~345 and.6 low alloy steels (WC6, WC9) low alloy steel (such as carbon steel and Cr Mo steel) valve manufacture can be applied to many kinds of work medium, including saturated and superheated steam, hot and cold oil, natural gas and air. The working temperature of the carbon steel valve can be used at 500 degrees, and the low alloy steel valves can be used over 600 degrees celsius. At low temperatures, the mechanical properties of low alloy steels are higher than those of carbon steels.High temperature and high pressure valves for non corrosive media operating at temperatures between 29~595 and 29~650; C5 and C12 are suitable for high temperature and high pressure valves of corrosive media operating at temperatures between C and C.
Valve material, a wide range of applicable to all kinds of different conditions. Now the commonly used valve material, internal material and sealing surface material is introduced as follows.Valve material commonly used1. gray iron gray iron valve for its low price, wide range of applications and applied in all fields of industry. They are usually used in the medium of water, steam, oil and gas, and are widely used in chemical, printing and dyeing, oil refining, textiles, and many other industrial products which have little or no effect on iron pollution.Suitable for working temperature between - 15 ~ 200 degrees, low pressure valve nominal pressure PN is less than 1.6MPa.2 FCMB for working temperature between - 15 ~ 300 DEG C, nominal pressure PN is less than or equal to 2.5MPa in the low pressure valve. Applicable medium is water, sea water, gas, ammonia and so on.3 ductile cast iron ductile iron is a kind of cast iron, the cast iron, nodular or spherical graphite instead of flake graphite in gray cast iron. This change in the internal structure of the metal makes its mechanical properties better than ordinary gray iron, and does not harm other properties. Therefore, the valves made of ductile iron use more pressure than those made of gray iron. Suitable for working temperature between - 30 ~ 350 DEG C, nominal pressure PN is less than or equal to 4.0MPa in the low pressure valve.Applicable medium is water, sea water, steam, air, gas, oil and so on.
Valve body performance of commonly used materialThe main parts of the valve material, first of all should take into account the physical properties of the working medium (temperature, pressure) and chemical properties (corrosive) and so on. At the same time, we should also know the degree of cleanliness of the medium (whether there is solid particles). In addition, we should also refer to the relevant regulations and requirements of the state and the use of the department.Many kinds of materials can meet the requirements of the valve in a variety of different operating conditions. However, the right and reasonable choice of valve material, you can get the valve's most economical service life and best performance.
Austenitic stainless steel 7. austenitic stainless steel containing about 18% chromium and 8% nickel. 18-8 austenitic stainless steel is often used as a valve body and valve cover material under high temperature and too low and very strong corrosion conditions. With 18-8 stainless steel as substrate, adding molybdenum and slightly increasing nickel content, essentially increase the corrosion resistance. Valves made of this steel can be applied to a wide range of chemicals, such as acetic acid, nitric acid, alkali, bleach, food, juice, carbonic acid, tanning liquid, and many other chemicals.In order to apply the high temperature range and further change the composition of the material, the addition of niobium into this stainless steel is known as 18-10-Nb and the temperature can be applied to 800 degrees centigrade.Austenitic stainless steel is usually used at very low temperatures and will not become brittle, so valves made of such materials (such as 18-8 and 18-10-3Mo) are suitable for low temperature work. For example, liquid gases are transported, such as natural gas, methane, oxygen and nitrogen gas.Valve suitable for corrosive medium between working temperature between 196~600 and C. Austenitic stainless steel is also an ideal cryogenic valve material.8 "Monel alloy Monel" is a kind of very good corrosion resistance of high nickel - copper alloy. This material is often used in valves conveying alkali, salt solutions, food, and many gas free acids, especially sulphuric acid and hydrofluoric acid. "Monel alloy" is very suitable for steam, water and marine environment. Mainly used in valves containing fluorine chlorate medium.
