What are the commonly used valve materials

There are various materials commonly used for valves, and different materials can be selected according to different usage environments and requirements. Here are some common valve materials and their characteristics:

1、 Metal material

carbon steel

Carbon steel refers to a carbon iron alloy with a carbon mass fraction of no more than 2%, typically containing small amounts of impurities such as silicon, phosphorus, and oxygen.

The commonly used carbon steel grades for valves are WCB and A105, with WCB being cast steel and A105 being forged steel.

At room temperature, the basic structure of these two types of carbon steels is mainly ferrite, with a small amount of pearlite.

It can be widely used in non corrosive environments, and its mechanical properties can meet most requirements.

Alloy steel

Alloy steel is a type of steel made by refining carbon steel with the addition of alloying elements such as chromium, nickel, molybdenum, and titanium.

According to the content of alloying elements, it can be divided into low-alloy steel (total mass fraction of alloying elements not exceeding 5%), medium alloy steel (total mass fraction of alloying elements between 5% and 10%), and high alloy steel (total mass fraction of alloying elements greater than 10%).

The commonly used alloy steel valve material in hydrogenation units is WC6 or WC9, which belongs to chromium molybdenum steel. It has good strength and high-temperature oxidation resistance at high temperatures, and has certain resistance to sulfide and hydrogen corrosion.

stainless steel

The main element that prevents rust in stainless steel is chromium. Chromium compounds form a dense passivation film on the surface of stainless steel, which can effectively prevent hydrogen or corrosive media from binding with Fe atoms, thereby preventing corrosion and rust.

Stainless steel is divided into ferritic stainless steel, austenitic stainless steel, martensitic stainless steel, and duplex stainless steel according to different metallographic structures.

The commonly used austenitic stainless steel materials in the petrochemical industry are 304 and 316, which have good mechanical properties, temperature applicability, and corrosion resistance.

Dual phase stainless steel contains both austenitic and ferritic structures, with each structure accounting for no less than 30%. It combines the characteristics of both ferritic and austenitic stainless steels.

Other metal materials

Materials such as gray cast iron, malleable cast iron, ductile iron, etc. are mainly used in specific low-pressure, low-temperature, or non corrosive medium environments.

High temperature copper is suitable for high-temperature steam and petroleum products.

Low temperature steel is suitable for low-temperature environments, such as ethylene, propylene, liquid natural gas and other media.

2、 Non metallic material

Plastic valves: valves made of materials such as nylon, chlorinated polyether, polyvinyl chloride, polytetrafluoroethylene, etc., are mainly used in corrosive media or applications that require lightweight and durability.

Ceramic valves: Ceramic valves are generally used in working conditions below 150 ℃ due to their poor resistance to temperature and sudden changes. But there are also high-performance ceramic valves that can withstand high temperatures below 1000 ℃.

Glass valve: Poor resistance to temperature and sudden changes, generally used for working conditions below 90 ℃.

Enamel valve: The temperature resistance is limited by the sealing ring material, and the maximum operating temperature does not exceed 150 ℃.

3、 Special material valve

Rubber diaphragm valves, such as natural rubber diaphragm valves and nitrile rubber, chloroprene rubber diaphragm valves, are mainly used in situations that require isolation from corrosive media or good sealing performance.

In summary, the selection of valve materials should be comprehensively considered based on specific usage environments, medium characteristics, temperature and pressure factors. When selecting, one can refer to the characteristics and applicable scope of the various materials mentioned above to ensure that the selected valve can meet the usage requirements and have good performance.