How to protect the valve from corrosion?

Summary:The valve is a control component in the fluid conveying system, which has the functions of cut-off, regulation, diversio...
The valve is a control component in the fluid conveying system, which has the functions of cut-off, regulation, diversion, prevention of reverse flow, stabilization, diversion or overflow and pressure relief. Valves used in fluid control systems, ranging from the simplest shut-off valves to the various valves used in extremely complex automatic control systems, have a wide range of varieties and specifications.

  The corrosion of the valve is usually understood as the damage to the metal material of the valve under the action of a chemical or electrochemical environment. Since the "corrosion" phenomenon occurs in the spontaneous interaction between the metal and the surrounding environment, how to isolate the metal from the surrounding environment or use more non-metallic synthetic materials is the focus of anti-corrosion.

  The valve body includes the valve cover, which occupies most of the weight of the valve and is in constant contact with the medium. Therefore, the valve body is often selected from the valve body material. The anti-corrosion of the valve body is mainly based on the correct selection of materials. Although there are abundant anti-corrosion materials, it is not easy to choose the right one, because the problem of corrosion is very complicated. For example, sulfuric acid is very corrosive to steel when the concentration is low, and when the concentration is high, the steel is produced. Passivation film can prevent corrosion; hydrogen only shows strong corrosiveness to steel under high temperature and high pressure. The corrosion performance of chlorine gas is not large when it is in a dry state, and the corrosion performance is very strong when there is a certain humidity, and many materials cannot be used. . The difficulty in selecting valve body materials lies in not only considering corrosion issues, but also considering factors such as pressure and temperature resistance, whether it is economically reasonable, and whether it is easy to purchase. So it must be hard.

   There are two forms of corrosion of the valve body, namely chemical corrosion and electrochemical corrosion. Its corrosion rate is determined by the temperature, pressure, chemical properties of the medium and the corrosion resistance of the valve body material. The corrosion rate can be divided into six levels:

  1. Complete corrosion resistance: the corrosion rate is less than 0.001 mm/year;
  2. Extremely resistant to corrosion: the corrosion rate is 0.001 to 0.01 mm/year;
  3. corrosion resistance: corrosion rate 0.01 to 0.1 mm/year;
  4. Still corrosion resistant: the corrosion rate is 0.1 to 1.0 mm/year;
  5. Poor corrosion resistance: the corrosion rate is 1.0 to 10 mm/year;
    6. Not corrosion resistant: the corrosion rate is greater than 10 mm/year.

  The second is to take lining measures, such as lining lead, lining aluminum, lining engineering plastics, lining natural rubber and various synthetic rubbers. If the media conditions permit, this is an economical method. Furthermore, in the case of low pressure and temperature, using non-metal as the main material of the valve can often be very effective in preventing corrosion. The outer surface of the valve body is also corroded by the atmosphere, and generally steel materials are protected by painting.

Ningbo Baodi Plastic Valve Co., Ltd. is professional China VALVES Manufacturers and VALVES suppliers.Founded in 2006, the enterprise has established ISO9001 quality system to support the quality guideline: supported by Technology, Meticulously Researching, Professionally Manufacturing and Permanently Creating New Records. The first class production equipments and advanced manufacturing skills are introduced at the same time, involving KRAUSS-MAFFEL CPVC pipe production line and Haitian CPVC Plastic Molding Machine of 2800 tons. In order to ensure the quality of wholesale VALVES, the raw materials like CPVC and PVDF are wholly imported from Noveon (USA) and Atofina (France).