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Enameled lining: Enameled lining products are a composite of glass and metal; they possess not only the corrosion resistance, smoothness, and wear resistance of glass, but also the mechanical properties such as pressure resistance and heat resistance of metal components. The raw materials used for glass lining are glass, a binder (base glaze or intermediate transition layer), and metal materials. Carbon steel and cast iron are commonly used metal materials for glass linings. Reference can be made to HG2432 \"Technical Requirements for Enameled Equipment\". Glass lining involves applying glass to a metal surface to form a corrosion-resistant coating, and its corrosion resistance depends on the properties of the glass used. Construction and inspection ① The construction methods for glass linings can be divided into three processes: blowing and pasting method, loose sleeve expansion lining method, and spraying and firing method. (a) Blowing and pasting method. Lining technology using manual or compressed air blowing. First, the inner surface of the metal product to be lined is descaled by sandblasting, then a primer is applied and dried ； The glass mixture is then melted at 800–1000°C; the molten glass is taken out and shaped by manual methods or with compressed air, and applied to the inner surface of metal components that have been heated to around 800°C. Due to being under a certain compressive stress, the frit adheres firmly to the surface of the metal component, forming a glass-metal composite. The products manufactured by this method include pipes, pipe fittings, valves, small reactors, and tower sections, which have proven to be highly effective in chemical manufacturing. (b) Loose sleeve expansion lining method. A glass tube of appropriate diameter is inserted into a metal tube coated with a base glaze. After heating until the glass tube becomes soft, compressed air is introduced; under the pressure of this air, the glass tube expands and adheres to the inside of the metal tube. Finally, the ends of the glass tube are cut flat. A flange connection structure is adopted during installation. This method can be used to produce straight tubes with glass lining. (c) Spraying and firing method. Enameled glass is a type of specialized technology within industrial enamel. Enameled products, such as reaction kettles, storage tanks, mixers, pipes and pipe fittings, valves, pumps, tower sections of various specifications and models, are widely used in chemical equipment. ②The inspection of the glass-lined layer focuses on checking for defects such as sand holes, cracks, and incomplete coating in the glass lining. If any defects are found, they should be repaired, repainted, or fire-clad promptly to meet the required standards. Micropore inspection is carried out using an electric spark detector. ③The main defects of the glass-lined layer include porcelain loss, micropores, and microcracks. There are several methods for repairing glass linings: (a) micro-porosity defects. The repair methods include mechanical repair and mortar bonding. Mechanical repair involves first treating the micro-hole area, and then using corrosion-resistant metal materials such as platinum and tantalum to create bolts that are screwed into the defective micro-hole areas to clamp them in place. For clay-based repair, the porous areas are first treated, after which a corrosion-resistant repair material, resinous clay, or siliceous clay is used to fill and smooth those pores, followed by curing to complete the repair. (b) Porcelain loss defect. Depending on the size of the defect, mechanical repair or patching with putty can be used for restoration. When the area of damaged porcelain is large, rework and repainting are the only options. (c) Microcrack defects. It can generally be repaired using the mud bonding method. If the repair of defects in the glass-lined layer is not effective, it is necessary to improve product quality during glass lining production, and to strictly follow operating procedures and carry out proper maintenance to effectively extend its service life.