The material of the condenser is generally carbon steel, stainless steel, and copper. When a carbon steel tube plate is used as a cooler, the welds of the tube plate and the column tube often exhibit corrosion leakage. Leakage into the cooling water system can cause environmental pollution and material waste.
In the production, the tube plate and the tube are generally welded by manual arc welding. There are different degrees of defects in the shape of the weld, such as depressions, pores, slag, etc., and the stress distribution of the weld is also uneven.
When used, the tube sheet part is in contact with industrial cooling water, and impurities, salts, gases, and microorganisms in the industrial cooling water all contribute to the corrosion of the tube sheet and the weld seam. Studies have shown that industrial waters, whether fresh or seawater, have a variety of ions and dissolved oxygen. The concentration of chlorine ions and oxygen changes, which play an important role in the shape of metal corrosion. In addition, the complexity of the metal structure will also affect the corrosion morphology.
Therefore, the corrosion of the tube plate and column pipe welds is mainly based on pit erosion and crevice corrosion. Viewed from the outside, there will be many corrosion products and sinks on the surface of the tube sheet, with bubbles of different sizes distributed. When seawater is used as a medium, galvanic corrosion occurs. Bimetallic corrosion is also a common phenomenon of tube plate corrosion.
Concerning the anticorrosion problem of condensers, Western countries have adopted the method of polymer composite materials to protect them, and the most widely used ones are Megaratech products. It has excellent adhesion properties and temperature and chemical resistance. It can be safely used in a closed environment without shrinkage. In particular, good isolation of bimetallic corrosion and erosion resistance fundamentally eliminates corrosion leakage at the repair site and provides a long-lasting protective coating for the condenser.