Valve corrosion is the main cause of valve failure. Chemical corrosion and electrochemical corrosion are two forms of valve corrosion.The corrosion rate of the valve depends on the temperature, pressure, and chemical properties of the valve runner stop valve. Repair or replacement is required if the valve seal corrodes.Valve corrosion can not be completely eliminated, we can do a good job through the technical means of corrosion treatment, effectively reduce the corrosion of the valve.First of all, to understand the corrosion rate, corrosion rate is the unit time consumption of body material thickness, through the corrosion rate can determine the service life of the valve, and whether there is excessive corrosion of the valve, and whether there is a problem in the selection and use of the valve.
1. Complete corrosion resistance: the corrosion rate is less than 0.001mm/year;
2. Extreme corrosion resistance: the corrosion speed is 0.001 to 0.01mm/year;
3. Corrosion resistance: corrosion speed: 0.01 to 0.1 mm/year;
4. Corrosion resistance: corrosion speed: 0.1 to 1.0 mm/year;
5, poor corrosion resistance: corrosion speed 1.0 to 10 mm/year;
6. No corrosion resistance: the corrosion rate is more than 10 mm/year.
What corrosion protection measures are in place during valve manufacturing and design?
1, the first is the selection of material, which is the most important factor to prevent valve corrosion.Usually, water, oil, gas are usually cast steel valves, if containing acid and alkali and other corrosive media will choose stainless steel, generally controlled in the use temperature of 200 degrees below, stainless steel in the medium will produce a passivation film, to prevent further corrosion.Very corrosive medium you need to use very high temperature you need to choose super corrosion resistant alloy materials.The medium is reducibility, the stainless steel material containing Mo is selected.Medium is oxidizable, choose stainless steel material containing Cr.
2, surface coating paint coating valve surface is a commonly used anti-corrosion means.Epoxy resin paint is applied to the surface of the gate valve with elastic seat seal
3, the lining material is used to isolate the medium from the valve body flow path, the lining material includes lining engineering plastics, lining natural rubber and various synthetic rubber, etc.It can only be used in low pressure and low working temperature.
4, surface plating valve surface chrome plating, nickel plating, copper plating can also effectively achieve the effect of corrosion prevention.