Chemical industry: corrosion resistance and sealing solutions in multi-media environments.

The production process in the chemical industry is complex, involving a wide range of media with strong corrosivity, from strong acids and alkalis to various organic solvents. This places extremely high demands on the corrosion resistance and sealing reliability of pipeline connecting components. In chemical plants, flanges serve not only as simple mechanical connections but also as critical barriers ensuring the tightness of the process flow and preventing the leakage of harmful media. For example, in the chlor-alkali industry, wet chlorine gas is highly corrosive to most metals, necessitating the use of special alloys or plastic-lined flanges. In PTA (Purified Terephthalic Acid) plants, the high-temperature acetic acid environment requires flange materials with excellent resistance to intergranular corrosion. Furthermore, the frequent start-up and shutdown in chemical production leads to cyclic changes in temperature and pressure, posing severe challenges to the sealing durability of the flange-gasket-bolt system. Therefore, in the chemical industry, flange selection needs to precisely match the characteristics of the medium and process parameters. Special materials such as Hastelloy, titanium, and duplex stainless steel are widely used, and attention is paid to the optimal combination of sealing surface types (such as tongue-and-groove surfaces) and gasket materials to achieve intrinsic safety and long-term operation.