Selection of valve materials for several acidic media

Selection of valve materials for several acidic media

t: Selection of valve materials for several acidic media
k: Chemical Valves, Stainless Steel Valves, Pump Valves, Valve Material Selection, Fluorine-Lined Valve, Rubber-Lined Valves, Plastic Lined Valves, High-Alloy Stainless Steel Valves, Fluoroplastic Valves

d: Corrosion is one of the most headaches of chemical valves. We must pay attention to the scientific selection of valve materials for some acidic media.

Corrosion has always been one of the most headaches of chemical equipment. If you are not careful, it will damage the equipment, and it will cause trouble and even cause disaster. According to relevant calculations, about 60% of the damage of chemical equipment is caused by corrosion. Therefore, in the selection of chemical valves, we must pay attention to the scientific selection of material. There is generally a misunderstanding that stainless steel is an "omnipotent materia". Stainless steel valves are used regardless of media and environmental conditions, which is very risky.

Here are some key points for selecting materials for some common chemical media:

sulfuric acid
As one of the strong corrosive media, sulfuric acid is an important industrial raw material that is widely used. Different concentrations and temperatures of sulfuric acid have different corrosion to materials. Carbon steel and cast iron have good corrosion resistance for concentrated sulfuric acid with a concentration above 80% and temperature less than 80 °C, but they are not suitable for high-speed active sulfuric acid and are not suitable as a material for pump valves. Generally, stainless steel, such as 304 (0Cr18Ni9) and 316 (0Cr18Ni12Mo2Ti), has limited use for sulfuric acid media. Therefore, the pump valve for transporting sulfuric acid is generally made of high-silicon cast iron (difficult to cast and process) and high-alloy stainless steel. Fluoroplastics have a good resistance to sulfuric acid, and the use of a fluorine-lined valve is a more economical choice.

Hydrochloric acid
Most metal materials are not resistant to hydrochloric acid corrosion (including various stainless steel materials). And, molybdenum-containing high-silicon iron can only be used for hydrochloric acid with   temperature of 50 ° C and a concentration below 30%. In contrast to metallic materials, most non-metallic materials have excellent corrosion resistance to hydrochloric acid, so rubber-lined valves and plastic lined valves (such as polypropylene, fluoroplastic, etc.) are the best choice for transporting hydrochloric acid.

Nitric acid
Generally, most metals are quickly corroded and damaged in nitric acid. Stainless steel is the most widely used nitric acid-resistant material. It has excellent corrosion resistance to all concentrations of nitric acid at normal temperature. It is worth mentioning that molybdenum-containing stainless steels (such as 316, 316L) are less resistant to nitric acid than ordinary stainless steels (such as 304, 321), sometimes even worse. For high temperature nitric acid, titanium and titanium alloy materials are generally used.

Acetic acid
It is one of the most corrosive substances among organic acids. Common steel is severely corroded in acetic acid at all concentrations and temperatures. Valve stainless steel is an excellent acetic acid resistant material, and molybdenum-containing stainless steel 316 can also be used for high temperature dilute acetic acid vapor. High-alloy stainless steel valves or fluoroplastic valves are available for high temperature, high concentration acetic acid or other corrosive media.

Selection of valve materials for several acidic media
Bolted Bonnet 2500LB Globe Valve - Dervosforge