Chemical industry
The chemical industry is the fundamental and pillar industry of the national economy, and its development speed and scale have a direct impact on various aspects of the social economy. The chemical industry is characterized by a wide range of categories, complex processes, diverse products, and a large number of pollutants discharged during production, with high toxicity. Therefore, the sustainable development path of the chemical industry has important practical significance for human economic and social development. The modern chemical industry has always been committed to reducing emissions, increasing factory safety and environmental protection, facing strict government management requirements that vary in content for different countries and markets. CNNC Suvalves can provide the highest quality valve products to meet the needs of chemical production. CNNC Suzhou Valve has obtained all applicable international standard certifications for the chemical industry solution, meeting the strictest environmental standards, including European low leakage standards.
In the chemical industry, valves with a straight through flow channel are generally selected due to their small flow resistance. Additionally, valves for cut-off and open media are commonly used. These valves are easy to adjust flow and are used for controlling flow. Ball valves and plug valves are suitable for reversing and diverting flow, and the sliding of the closing part along the sealing surface has a wiping effect. This type of valve is suitable for media with suspended particles. The commonly used chemical valves we see include globe valves, ball valves, gate valves, safety valves, check valves, plug valves, and so on. The mainstream of chemical valve media contains chemical substances, and most of them contain acid and alkali corrosive media. The chemical industry may involve various processes. Control is established through electrical, hydraulic, pneumatic, and sometimes manual means. The valve used should be able to handle pressure and prevent any leakage. Different valves are known for their different functions.
When selecting valves in the chemical industry, the first thing to pay attention to is the scientific nature of material selection. There is usually a misconception that stainless steel is a "universal material", and it is very dangerous to hold stainless steel valves regardless of the medium and environmental conditions.
Key points for selecting materials for some commonly used chemical media: sulfuric acid: As one of the highly corrosive media, sulfuric acid is an important industrial raw material with a wide range of uses. The corrosion of materials varies greatly with different concentrations and temperatures of sulfuric acid. For concentrated sulfuric acid with concentrations above 80% and temperatures below 80 ℃, carbon steel and cast iron have good corrosion resistance, but they are not suitable for high-speed flow of sulfuric acid and are not suitable as materials for pump valves; Ordinary stainless steels such as 304 (0Cr18Ni9) and 316 (0Cr18Ni12Mo2Ti) are also limited in their use for sulfuric acid media. Therefore, pump valves for transporting sulfuric acid are usually made of high silicon cast iron (with high difficulty in casting and processing) and high alloy stainless steel (alloy 20). Fluoroplastics have good sulfuric acid resistance, and using fluorine lined valves is a more economical choice. Hydrochloric acid: Most metal materials are not resistant to hydrochloric acid corrosion (including various stainless steel materials), and high silicon iron containing molybdenum can only be used for hydrochloric acid below 50 ℃ and 30%. Contrary to metal materials, the vast majority of non-metallic materials have good corrosion resistance to hydrochloric acid, so lined rubber valves and plastic valves (such as polypropylene, fluoroplastics, etc.) are better choices for transporting hydrochloric acid. Nitric acid: Most metals are rapidly corroded and destroyed in nitric acid. Stainless steel is a more widely used nitric acid resistant material, which has good corrosion resistance to all concentrations of nitric acid at room temperature. It is worth mentioning that stainless steel containing molybdenum (such as 316, 316L) not only has better corrosion resistance to nitric acid than ordinary stainless steel (such as 304, 321), but sometimes even worse. For high-temperature nitric acid, titanium and titanium alloy materials are usually used. Acetic acid: It is one of the more corrosive substances in organic acids. Ordinary steel will severely corrode in all concentrations and temperatures of acetic acid. Stainless steel is an excellent acetic acid resistant material, and 316 stainless steel containing molybdenum can also be suitable for high temperatures and dilute acetic acid vapor. For demanding requirements such as high temperature and high concentration acetic acid or containing other corrosive media, high alloy stainless steel valves or fluoroplastic valves can be selected.