Non-metallic expansion joints are indeed one of the pressure pipe elements. Pressure piping elements refer to various components used in industrial piping systems for the purpose of performing the function of transporting fluids (gases, liquids or suspensions). These elements include, but are not limited to, pipes, fittings (elbows, tees, reducers), valves, flanges, gaskets, fasteners, expansion joints (metallic and non-metallic), filters, traps, compensators, and the like.

The non-metallic expansion joint, as a special compensator, has the main function of absorbing axial, transverse and angular displacements caused by thermal expansion and contraction, vibration or installation errors in the pipe system. It is able to help reduce stress on pipes and equipment and protect the system from damage. Non-metallic expansion joints are usually made of non-metallic materials such as fibrous fabric, rubber, high temperature resistant materials, and are suitable for use in high temperatures, corrosive, or where soft connections are required.

According to relevant regulations and standards, such as American ASME code, European PED directive, etc., non-metallic expansion joints as pressure pipe elements, their design, manufacture, inspection and testing need to meet specific safety and performance requirements. In some countries and regions, the production and use of non-metallic expansion joints may require obtaining specific certifications or licenses. For example, manufacturing of metal expansion joints in China needs to comply with special equipment production requirements, and non-metal expansion joints may have similar requirements.