What is valve corrosion?

Corrosion of valves is usually understood as the damage to the metal materials of the valve caused by the chemical or electrochemical environment. Since the corrosion appears in the spontaneous interaction between the metal and the surrounding environment, the focus of corrosion prevention is how to isolate the metal from the surrounding environment or more use of non-metallic synthetic materials. Valve body (including the valve bonnet) takes the most weight of a valve, and often contact with the media, so the selection of the valve, in most cases, starts from the valve body material.

There are two forms of valve corrosion, namely, chemical corrosion and electrochemical corrosion. The rate of corrosion is determined by the medium's temperature, pressure, chemical properties and the ability of the valve body material to resist corrosion. The rate of corrosion can be divided into six categories.

1. Complete corrosion resistance: corrosion rate less than 0.001 mm/year.

2. Extreme corrosion resistance: 0.001 to 0.01 mm/year.

3. General corrosion resistance: 0.01 to 0.1 mm/year.

4. Fairly corrosion resistant: 0.1 to 1.0 mm/year.

5. Poor corrosion resistance: 1.0 to 10 mm/year.

6. Not corrosion-resistant: corrosion rate is greater than 10 mm / year.

How to prevent valve corrosion?

Corrosion prevention of the valve body is basically the correct choice of materials. Although the anti-corrosion materials are abundant, it's not easy to choose the right ones as the subject is quite complex. For example, sulfuric acid at low concentrations is very corrosive to steel, while sulfuric acid at high concentrations can passivate steel and thus prevent corrosion. Hydrogen only shows very strong corrosive properties to steel at high temperature and pressure. Dry chlorine is not very corrosive, but it is very corrosive when it is somehow humid. The difficulty in choosing valve materials is also that you can't consider corrosion only, you have to also consider the ability to withstand pressure and temperature, whether it is economically reasonable, and whether it is easy to buy.So this process must be attentive.

One is to adopt lining measures, such as lead lining, aluminium lining, engineering plastics lining, natural rubber lining and various synthetic rubbers. If the media conditions permit, this is a way to save money.

Second, in the case of low pressure and temperature, fluorine lined valves can often be very effective in preventing corrosion.

In addition, the external surface of the valve body is also subject to atmospheric corrosion, the general steel materials are painted to protect.

Related Products: stainless steel globe valve,  stainless steel ball valve.