Selection of the Material of the Slurry Pump


Dec 24,2023

In the face of different chemical media, how to choose the material of the slurry pump.

Selection of the Material of the Slurry Pump

In the face of different chemical media, how to choose the material of the slurry pump.

1. Hydrochloric acid. Most metal materials are not resistant to hydrochloric acid corrosion, when the concentration of hydrochloric acid is relatively high, including various stainless steel materials can not resist its corrosion, molybdenum-containing ferrosilicon can only be used for hydrochloric acid below 50 °C, 30%. Contrary to metal materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so rubber and plastic pumps (such as polypropylene, fluoroplastics, etc.) are good choices for transporting hydrochloric acid.

 2. Sulfuric acid. As one of the strong corrosive media, sulfuric acid is an important industrial raw material with a wide range of uses. For concentrated sulfuric acid with a concentration of more than 80% and a temperature of less than 80 °C, carbon steel and cast iron have good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, so carbon steel and cast iron should not be used for pump and valve materials; Even common stainless steels such as 304 and 316 are of limited use for sulphuric acid media. Therefore, pumps and valves for transporting sulfuric acid are usually made of high-silicon cast iron or high-alloy stainless steel, i.e. alloy 20, but they are very difficult to cast and process. Fluoroplastics have good resistance to sulfuric acid, and fluorine-lined pumps are a more economical option.

3. Nitric acid. As a strong oxidizing acid, most of the general metals are rapidly corroded and destroyed in nitric acid, at room temperature, fluoroplastics and stainless steel materials have strong corrosion resistance to nitric acid, it is worth noting that the corrosion resistance of molybdenum-containing stainless steel (such as 316, 316L) to nitric acid is not only not better than ordinary stainless steel (such as 304, 321), sometimes even inferior. For high-temperature nitric acid, titanium and titanium alloy materials are usually used.

4. Acetic acid It is one of the corrosive substances in organic acids, ordinary steel will be seriously corroded in acetic acid at all concentrations and temperatures, stainless steel is an excellent acetic acid resistant material, and 316 stainless steel containing molybdenum can also be suitable for high temperature and dilute acetic acid steam. For demanding requirements such as high temperature, high concentration acetic acid or other corrosive media, high-alloy stainless steel or fluoroplastic pumps can be selected.

 5. Alkali. The common chemical base is sodium hydroxide. Sodium hydroxide solutions below 80°C and at a concentration of 30% can be made of steel, and there are many factories that still use ordinary steel at 100°C and below 75%, which is economical and economical. The corrosion resistance of ordinary stainless steel to lye solution has no obvious advantage compared with cast iron, as long as a small amount of iron is allowed in the medium, stainless steel is not recommended. For high-temperature lye, titanium and titanium alloy or high-alloy stainless steel are mostly used. Generally, cast iron pumps can be used for low concentration lye at room temperature, and various chemical FRP pumps, chemical plastic pumps, PTFE magnetic pumps, stainless steel magnetic pumps, fluoroplastic magnetic pumps, high-temperature resistant magnetic pumps, etc. can be used for special requirements.

6. Ammonia (ammonia hydroxide) Most metals and non-metals are very slightly corroded in liquid ammonia and ammonia (ammonia hydroxide), and only copper and copper alloys are not suitable for use.
7Alcohols, ketones, esters, etc. Alcohols are common such as methanol, ethanol, ethylene glycol, propanol, etc.; Ketones such as acetone, butanone, etc.; Esters such as methyl ester, ethyl ester, etc., they are basically non-corrosive, and common materials can be used, but stainless steel materials are used for cleaning; In addition, it is worth noting that ketones and esters have solubility to a variety of rubbers, so you should pay attention to them when choosing machine seal materials.

7. Salt water and sea water. For media such as seawater, the corrosion rate of ordinary steel in sodium chloride solution and seawater and saltwater is not too high, and it is generally necessary to be protected by coatings; All kinds of stainless steel also have a very low uniform corrosion rate, but it may cause local corrosion due to chloride ions, and it is usually better to use 316 stainless steel material.