Shell and tube heat exchanger tube sheet corrosion protection

1. Introduction shell and tube heat exchanger is the most widely used as a heat exchanger on the production of chemical and other industries at present. It mainly consists of the housing, the tube plate, the heat transfer tubes, head, baffles and other components, material of ordinary carbon steel, copper, and stainless steel. During heat transfer, a fluid into the connecting pipe at the head, the flow in the pipe, the flow from the outlet head at the other end, which termed the tube; another fluid into the takeover of the housing, from Another takeover of the housing on the outflow, which is called the shell. With shell and tube heat exchangers large number of applications, due to the different heat exchanger configuration, materials, conditions, and cooling water quality and other factors, often leading to corrosion control, and nozzle tube plate at the leak, which seriously affect safety production, leakage into the cooling water system has caused environmental pollution waste materials, can lead to serious accidents. 2, the tube sheet corrosion causes and solutions 2.1 plate heat exchanger Corrosion of heat leakage is the most common use of equipment problems, leakage is mainly caused by corrosion, a small part is due to the heat exchanger selection and defects in the manufacturing process itself, heat exchangers, shell-and-tube heat exchanger corrosion in the form of two basic categories: electrochemical corrosion and chemical corrosion. Shell and tube heat exchangers in the production, tube plate and the tubes commonly used SMAW welding, weld shape varying degrees of defects such as dents, pores, slag, etc., welding stress distribution is not uniform. Tube plate portion when the use of general and industrial cooling water contact, and industrial cooling water impurities, salt, gas, micro-organisms will constitute the tube plate and weld corrosion. This is what we often say that the electrochemical corrosion. Studies have shown that industrial water either fresh or sea water, there will be a variety of ions and dissolved oxygen, which changes the concentration of chloride ions and oxygen corrosion shape of the metal plays an important role. In addition, the complexity of the metal structure can also affect the corrosion morphology. Thus, the tube plate and tube weld corrosion to pitting and crevice corrosion based. From the outside, the tube sheet surface will have a lot of corrosion products and accumulated sediments, the distribution of pits of varying sizes. Seawater as media, will produce galvanic corrosion. Chemical etching is the corrosive medium, the heat exchanger tube plate contacts a wide variety of chemical mediators, would be corrosive chemical media. In addition, the heat exchanger tube to tube sheet also between certain bimetallic corrosion. Some long-term erosion of the tube plate further corrosion medium. Particularly with fixed tube sheet heat exchanger, as well as thermal stress, the joint of the tube plate and the heat transfer tubes can easily leak, resulting in heat exchanger failure. 2.2 condenser tube sheet corrosion solutions using US technology products for corrosion protection Wah, its products have excellent adhesion properties and resistance to temperature, resistance to chemical corrosion, material is 100% solids, no volatiles in a closed environment where you can safely and will not shrink, especially good isolation material bimetallic corrosion and erosion resistance, excellent performance, excellent corrosion resistance, and fundamentally eliminate the leakage corrosion repair site can provide a long-term protection for members coating. Polymer composite material is polymer, metal or ceramic ultra-fine powders, fibers and other materials for composite made of the role of the curing agent, curing accelerator material. Learn from each other in the performance of a variety of materials with each other to produce a synergistic effect, the overall performance is better than the original composition of the composite material. With strong adhesion, mechanical properties and resistance to chemical corrosion and other properties, which are widely used in metal equipment machinery wear, scratches, dents, cracks, leaks, trachoma and other casting repair and various chemical tanks , reaction tanks, condensers, piping and other equipment of chemical corrosion protection and restoration. Advantage 2.3 US Wah polymer composite materials: (1) excellent adhesion performance, smooth steel surface adhesion of 295 kg / cm. (2) 100% solids, no shrinkage. (3) excellent resistance to chemical corrosion, isolation bimetallic corrosion. (4) to reach the United States USDA certified, non-toxic, harmless and will not cause pollution to the water quality. Case I: corrosion protection plant condenser tube plate: Case II: Fertilizers corporate board protection: