expansion joint

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As an elastic compensation element, the expansion joint boasts advantages such as reliable operation, good performance, and a compact structure. It is widely used in various infrastructure sectors including chemicals, 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? An expansion joint*, also commonly referred to as a compensator, is a flexible structure installed on container shells or pipelines 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, let’s compare the performance differences between metal expansion joints and non-metallic expansion joints to gain a deeper understanding of expansion joints. 1. Compensation function: Under the same external dimensions, the compensation capacity 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 compensating capacity 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 is 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-temperature corrosion at low temperatures; 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 maintain heat insulation, a thermal insulation 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 higher operating pressures. 8. Medium used: Metal expansion joints are suitable for liquids, gases, and powders. Non-metallic expansion joints can be used with both gases and liquids. As an important category of non-metallic expansion joints, rubber expansion joints possess a high capacity for displacement compensation; they can compensate for axial, lateral, and angular displacements. They also help to reduce noise and vibrations, and offer certain corrosion resistance. Compensator operation animation