- Current position：
- Home >
- News
Chemical enterprise with valve should choose what material
Since always, corrosion is the most headache chemical equipment, one of the dangers of have a little bit the immodesty, light is damage to the equipment, heavy then cause accidents and even cause disaster. According to the statistics, the destruction of chemical equipment about 60% is due to corrosion of the cause, so in chemical valve selection first to pay attention to the scientific selection. Usually there is a misunderstanding that stainless steel is the "universal material", no matter what the media and environmental conditions are holding out of stainless steel valves, this is very dangerous.
For the some commonly used chemical media talk about selection of key points:
Sulfuric acid
As one of the strong corrosive medium, sulfuric acid is use a wide range of important industrial raw material. Different concentration and temperature of sulfuric acid on the material corrosion difference is bigger, for concentration in more than 80%, the temperature is less than 80 ℃ of concentrated sulfuric acid, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high speed flow of sulfuric acid, is not used as a pump valve material; Ordinary stainless steel such as 304 (0 cr18ni9), 316 (0 cr18ni12mo2ti) in sulfuric acid medium also use limited. So delivery vitriolic pump valve usually adopts high silicon cast iron (casting and machining difficulty big), high alloy steel (twenty number alloy) manufacturing. Fluorine plastic has good resistance to sulfuric acid performance, the lining fluoride valve is a kind of more economical choice.
Hydrochloric acid
Overwhelming majority of metal materials are not resistant to hydrochloric acid corrosion (including all kinds of stainless steel material), molybdenum high silicon also can only be used for fifty ℃, below 30% hydrochloric acid. And metal materials contrary, the vast majority of non-metallic materials of hydrochloric acid has good corrosion resistance, so lined with rubber valves and plastic valve (such as polypropylene, fluorine plastic, etc.) is the best choice of conveying hydrochloric acid. Nitric acid general metal mostly in the nitrate rapid corrosion damage, stainless steel is the most widely used material, resistance to nitric acid to room temperature all concentration of nitric acid has good corrosion resistance, what is worth mentioning molybdenum stainless steel (such as 316, 316 l) on the corrosion resistance of nitrate not only not better than the ordinary stainless steel (such as 304, 321), sometimes even as. For high temperature nitric acid, usually by titanium and titanium alloy materials.
Acetic acid
It is the strongest in the organic acid corrosion one of material, common steel in all concentration and temperature of the acetic acid will severely corrosive, stainless steel is a good resistance to acetic acid materials, molybdenum 316 stainless steel can also suitable for high temperature and dilute acetic acid steam. For high temperature and high concentration of acetic acid or contain other corrosion medium etc required, can choose high alloy stainless steel valves or fluorine plastic valve.
