Many O-ring failures can be directly attributed to Improper installation during assembly. In spite of its simple appearance, the O-ring is a
precision device requiring care during installation. Some of the more frequent causes of O-ring failure due to careless handling are listed below
Damage to an O-ring during installation can occur when:
- 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.
- Insufficient lead-in chamfer.
- Blind grooves in multi-port valves.
- Oversize O-ring on piston seal application.
- Undersize O-ring on rod application.
- O-ring twisted/pinched during installation.
- O-ring not properly lubricated before installation.
- O-ring dirty upon installation.
- O-ring gland and/or other surfaces over which O-ring must pass during assembly contaminated with metal particles.
- 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 however, some specific solutions which are listed below:
IDENTIFICATION OF INSTALLATION FAILURE
- Break all sharp edges on metal components.
- Allow a 20° lead-in chamfer.
- Check all components for cleanliness before Installation.
- Tape all threads over which the O-ring will pass.
- Use an O-ring lubricant such as Parker 0-Lube or Parker Super 0-Lube if its use will not contaminate system.
- Double check O-ring to insure correct size and material.
- Be CAREFUL.
It is difficult to properly illustrate the many possible results of Installation Failure.
However, below is an example of a common failure mode, the "Skiving" of the O-ring surface due to cutting by metal components. These cuts are
usually very clean as if made with a very sharp knife. Another indication of bad installation will be small cuts or notches on the O-ring.
In almost all cases, the damage will appear on the surface of the O-ring AWAY from the bottom of the O-ring groove.