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The process media and products used in the chlor-alkali industry during production (such as NaOH, wet Cl2, saturated brine, HCl, H2SO4, etc.) are all highly corrosive. Corrosion not only poses threats to equipment and pipelines, but it also severely harms the physical and mental health of employees, pollutes the environment, endangers safe production, and leads to various accidents. Therefore, to fundamentally address the losses and hazards caused by corrosion and ensure safe production. I. Corrosion of NaOH and Protective Measures 1. Analysis of NaOH corrosion NaOH is a highly corrosive substance in chlor-alkali production. At room temperature, a dilute alkaline solution with a mass concentration of ≤30% (m/m), hereafter referred to as concentration, can form an insoluble passivation film on the steel surface, thereby granting it good corrosion resistance. However, the corrosion resistance of steel decreases as the concentration of the alkaline solution and the temperature increase. When the alkali concentration is >30%, the protective capacity of the passivation film decreases as the concentration rises; if the temperature also increases (>80°C), ordinary steel will suffer severe corrosion. There are two types of corrosion damage caused by NaOH to steel equipment: uniform corrosion and local corrosion. Local corrosion, which can be caused by various factors, is the more significant form; it can lead to sudden failure of the equipment, posing a serious threat. Steel becomes brittle when corroded by high temperatures and strong alkalis; if stress (either applied stress or residual stress) is present at the same time, stress corrosion of varying degrees occurs, which accelerates the degradation of the material. This phenomenon is generally referred to as \"alkali embrittlement\". According to available information, 15%~48% NaOH does not suffer from \"alkali embrittlement\" at temperatures below 82°C, whereas 50% NaOH experiences alkali embrittlement at 52°C. “\"Alkali embrittlement\" can cause cracks to appear in the heated areas on both sides of the welds in equipment, leading to alkali leakage; once leakage occurs, it is difficult to carry out repair welding. 2. Protective measures The NaOH production system should select appropriate materials based on the concentration and temperature of the alkaline solution. With a NaOH concentration of 30%–33% and a temperature of 85–95°C, this represents a stress-corrosion environment; therefore, for the non-standard equipment and pipelines in this system, ultra-low carbon austenitic stainless steels are the best choice, with 00Cr18Ni10, 0Cr18Ni9, and 00Cr17Ni14Mo2 being suitable options ； Materials such as Ni can be used when the NaOH concentration is 30%~33%, the temperature is 50°C, or the temperature is >85°C. This system can also use non-metallic materials such as polypropylene (PPH), chlorinated polyvinyl chloride (CPVC), and fiber-reinforced polyvinyl chloride (FRP/PVC), but the disadvantages are short lifespan and poor reliability. To prevent \"alkali embrittlement\" in steel equipment, reasonable structural design and manufacturing processes should be employed. While strictly controlling the quality of the materials, it is also necessary to improve the quality of manufacturing; appropriate heat treatment should be carried out after welding (for low-carbon and low-alloy steels, annealing at 600–650°C is used), and thorough inspection of welds is required to eliminate external and residual stresses. II. Corrosion of wet Cl2 and protective measures The Cl2 generated at the anode of the electrolyzer, being saturated with water vapor, is known as wet Cl2. Wet Cl2 often contains HCl and HClO, all of which cause many metal materials to corrode rapidly; when Cl2 contains water