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As an elastic compensation component, the expansion joint boasts advantages such as reliable operation, good performance, and a compact structure. It is widely used in various infrastructure sectors including chemical engineering, construction, water supply, drainage, petroleum, light and heavy industry, refrigeration, sanitation, plumbing, fire protection, and electricity, playing an important role in people’s lives. What is an expansion joint? The expansion joint XL, also commonly referred to as a compensator, is a flexible structure installed on container shells or pipes to compensate for the additional stresses caused by temperature differences and mechanical vibrations. Expansion joints are divided into: metal expansion joints and non-metallic expansion joints. Next, please follow the editor to compare the performance differences between metal expansion joints and non-metallic expansion joints, so as to gain a deeper understanding of expansion joints. 1. Compensation function: Under the same external dimensions, the compensation capability of non-metallic expansion joints is much greater than that of metallic expansion joints. Especially in terms of the compensation function for lateral displacement, the compensation capability of non-metallic expansion joints is almost an order of magnitude greater than that of metallic expansion joints. 2. Compensating resistance: Expansion joints act like elastic materials; they generate resistance when subjected to compression or tension. The resistance of metal expansion joints is much greater than that of non-metallic ones. This resistance is too high, which is detrimental to the system; it will damage the surrounding devices as well. 3. High-temperature and corrosion resistance: The material of non-metallic expansion joints not only possesses excellent high-temperature resistance but also resistance to acids and alkalis. The yield strength of ordinary carbon structural steel becomes zero at 600°C; at higher temperatures, it oxidizes and develops scaling. Carbon steel expansion joints are prone to cracking during operation, while stainless steel expansion joints suffer from low-leakage corrosion in low-temperature environments; moreover, their cost is quite high. 4. Thermal insulation and energy-saving performance: The structure of non-metallic expansion joints inherently possesses thermal insulation properties. Metal expansion joints, on the other hand, do not meet this requirement; to provide insulation, an insulating layer is also applied over their outer surface. 5. Maintenance and replacement performance: Non-metallic expansion joints require no maintenance throughout their normal service life ； Replacing non-metallic expansion joints is much easier than replacing metallic expansion joints. 6. Service life: The service life of expansion joints is closely related to environmental conditions. Non-metallic expansion joints have good wear and corrosion resistance; relatively speaking, under the same conditions, their service life is longer than that of metallic expansion joints. 7. Pressure resistance: Thanks to its flexible design and the special materials used, non-metallic expansion joints can withstand greater working pressures. 8. Medium used: Metal expansion joints are suitable for liquids, gases, and powders. Non-metallic expansion joints can be either gases or liquids.