An O-ring is a circular, ring-shaped elastic sealing device. First appearing in the mid-19th century as a sealing element for steam engine cylinders, the first O-rings were made of cast iron. Primarily used for static and reciprocating motion sealing, it prevents liquid or gas leakage and is widely used in hydraulic and pneumatic systems.
The choice of material directly affects sealing performance and service life. Commonly used materials include nitrile rubber, fluororubber, and silicone, but plastics, metals, and other materials can also be used. It is suitable for bearing seals, hydraulic systems, the automotive industry, aerospace, semiconductor manufacturing, and many other fields. Specifications are usually indicated by the inner diameter and cross-sectional diameter. International standards include American Standard AS568A and Chinese Standard GB/T3452.1. According to industry reports, the global O-ring market size was approximately 32.57 billion yuan in 2025 and is expected to maintain steady growth in the future.
