1. O-ring seals undergo heat hardening and oxidation
① Reason: Due to the working temperature exceeding the normal range of use, the elastomer hardens, the plasticizer evaporates and oxidizes, causing small surface cracks perpendicular to the direction of applied pressure on the sealing ring, resulting in local dents or cracking. This type of failure is mainly caused by exposure to dynamic and static seals in the air or sealing rings that come into contact with other air pollutants;
② Solution: Use materials with good antioxidant properties and high temperature resistance to reduce the working temperature of the system oil.
2. O-ring exhibits protrusion, biting, and spiral failure
① Reason: The main reasons for protrusion and biting failure are: excessive sealing gap, system pressure exceeding the sealing pressure bearing strength or no retaining ring added, sealing ring material not meeting the design hardness requirements, sealing ring groove processing size not meeting standard requirements, inappropriate selection of sealing ring (compared to sealing groove size being too large), etc. The main reasons for spiral failure are: low concentricity of parts, insufficient lubrication, and too soft sealing ring material. When some parts of the sealing ring are sliding while others are rolling, it can cause distortion or cracking;
② Solution: Reduce the sealing gap, select an appropriate size O-ring seal, and ensure that the concentricity of the parts meets the design requirements; The sealing groove is strictly processed according to the standard, using reinforced composite seals such as composite gaskets, using sealing ring materials that meet the design requirements or adding retaining rings to prevent the O-ring from being squeezed out.
3. The O-ring seal was damaged during installation
① Reason: This situation often occurs in dynamic and static seals. The main reason is that there are sharp edges or chamfers on the sealing groove that do not meet the standards, and lubricating oil was not applied during installation, resulting in the sealing ring being cut, twisted or stuck by sharp cutting edges, and the surface producing concave (or convex) marks, peeling or flaking phenomena;
② Solution: Process the sealing groove according to the design requirements, without leaving sharp edges. Apply lubricating oil on the groove and sealing ring during installation. When the O-ring passes through the thread, insert a metal sheet or strip on the thread to ensure smooth insertion of the sealing ring.
