Non-metallic expansion joints (also known as flexible expansion joints or fabric expansion joints) are primarily used to absorb thermal expansion, contraction, vibration, and displacement in piping systems while providing good tightness. They are commonly used in high-temperature, high-pressure or corrosive environments, so the choice of their material is crucial. The materials of non-metal expansion joints mainly include the following parts:
Cover
Fluorine rubber (FKM): Suitable for environments with high temperature and chemical stability requirements.
Silicone Rubber (VMQ): It has good heat resistance and oxidation resistance, and is suitable for high temperature environment.
Polytetrafluoroethylene (PTFE ）: Excellent chemical stability and temperature resistance, commonly used in chemical and pharmaceutical industries.
Neoprene (CR): It has good oil resistance and weather resistance, suitable for oil media and outdoor environment.
Ethylene propylene monomer (EPDM): Suitable for water and steam media with good heat and weather resistance.
Thermal insulation (Insulation Layer)
Glass fiber: Excellent insulation and high temperature resistance, suitable for high temperature environment.
Ceramic fiber: It is used in extreme high temperature conditions and has good heat insulation effect.
Reinforcement Layer
Aramid fibers (e.g. Kevlar): Provides high strength and abrasion resistance.
steel wire mesh: Increase the structural strength of expansion joints, especially in high pressure environments.
Guide layer (Guide Layer)
Stainless steel wire mesh or cloth: Used to protect the skin from external mechanical damage while enhancing the overall structure.
connecting flange
Carbon steel: Suitable for general environments and lower temperatures.
Stainless Steel: Use in corrosive environments, such as seawater or chemical delivery systems.
Alloy steel: Used in high temperature and high pressure environments, such as boiler systems in power plants.
The material combination of non-metallic expansion joints should be selected according to specific application conditions (such as medium, temperature, pressure, etc.) to ensure the safe and reliable operation of the expansion joints under predetermined working conditions. The following factors are usually considered when designing and selecting models:
Temperature range: From low temperature to high temperature, ensuring that the material does not degrade due to temperature changes.
Chemical compatibility: The material must be compatible with the conveying medium to avoid corrosion or degradation.
pressure: Materials and structures are required to withstand the maximum working pressure in the system.
Displacement capacity: Material and design to accommodate axial, lateral and angular displacements.
Service life: The material must have sufficient durability to meet the expected service life.
In special applications, composites, specialty rubbers, or other custom-made materials may also be employed to meet more complex needs.