A non-metallic expansion joint is a device used to absorb axial, lateral, or angular displacements in a piping system and is mainly made of non-metallic materials to accommodate environments with high temperatures, corrosive, or special media. The following is an illustration of the basic structure of a non-metallic expansion joint and its components:
The basic structure of a non-metallic expansion joint usually includes the following parts:
Cover/Liner: This is the main flexible part of the expansion joint, which is usually composed of multiple layers of high temperature and corrosion resistant non-metallic materials, such as aluminum silicate fiber, ceramic fiber, polytetrafluoroethylene (PTFE) or special rubber, etc. The skin is able to withstand the displacement of the pipe and absorb stress.
Thermal insulation (Insulation Layer)Located on the inside of the skin, made of aluminum silicate cotton or other thermal insulation material, used to reduce heat transfer and protect the skin from overheating.
Reinforcement Layer: Usually stainless steel wire mesh or other metal mesh to increase the mechanical strength and stability of the expansion joint and prevent deformation under pressure.
inner baffle (Inner Flange/Baffle): There will be inner baffles in some designs to guide the flow of media and prevent the media from directly impacting the skin, usually connected to the inlet frame in the direction of flue gas flow.
Frame/Structure: Made of metallic material to provide support and structural stability to the expansion joint, usually with inlet and outlet frames.
Sealing material (Sealing Material): It is used to improve the sealing performance of expansion joints and prevent media leakage. The common ones are silicone rubber strips or other sealing materials.
Flanges: Used to connect expansion joints to piping systems, either welded or bolted flanges.
Tie Rods: Used to maintain the correct alignment of the expansion joint during installation and operation to avoid excessive displacement, should be loosened appropriately after installation to allow free expansion.
Wear Resistant Layer: In some designs, wear layers are added on the inside or outside of the skin to improve the durability of the expansion joint in abrasive media environments.
Heat insulating Dust Cover: Some designs will have an additional jacket to protect the skin from dust and external environmental factors.
Working Principle
Non-metallic expansion joints absorb thermal expansion, contraction, shock or displacement in the pipeline system by the extension and contraction of their flexible skin, thereby reducing stress in the pipeline system and protecting the pipeline and equipment from damage.
Please note that the specific design of non-metallic expansion joints may vary depending on the manufacturer, application environment, and working conditions, and the above construction is for a basic reference only. In practical applications, the detailed drawings and installation guidelines provided by the manufacturer should be referred to.