Many O-ring failures can be directly attributed to improper installation. In spite of its simple appearance, the O-ring is a precision device requiring care during installation. Leakage will often be instantaneous. Installation damage is generally evidenced by a clean line in the seal, often in a pattern consistent with the hardware.
Some of the more frequent causes of O-ring failure due to careless handling are:
1. There are sharp corners on mating metal components such as the O-ring gland or threads over which the O-ring must pass during assembly. Picture shown of O-ring with slice due to a thread cutting the O-ring
2. Insufficient lead-in chamfer. See diagram for recommendation:
3. Blind grooves in multi-port valves.
4. Oversize O-ring on piston seal application.
5. Undersize O-ring on rod application.
6. O-ring twisted/pinched during installation.
7. O-ring not properly lubricated before installation.
8. O-ring dirty upon installation.
9. O-ring gland and/or other surfaces over which O-ring must pass during assembly contaminated with metal particles.
10. General Carelessness.
Probably the best way to prevent damage to O-rings during installation is the use of good old-fashioned “Common Sense.” There are some specific solutions which are listed below:
1. Break all sharp edges on metal components.
2. Provide a 20° lead-in chamfer.
3. Check all components for cleanliness before installation.
4. Tape all threads over which the O-ring will pass.
6. Double check O-ring to ensure correct size and material.
7. Be CAREFUL.