O Rings To Fit In Non-Circular Grooves
Contrary to popular belief, O-Rings can be used in rectangular and non-circular groove patterns (Also known as ‘racetrack grooves’, ‘wandering grooves’ or ‘custom plan views’ non-circular grooves). However, there are certain rules to follow.
The main design consideration when using an O-Ring in these applications is the corner or the smallest radius. The inside radius should be at least three times the O-Ring cross sectional diameter, with six times considered optimal. Over-stressing of the O-Ring around the bend increases the chance of corner leakage due to corner crease. A radius developed at six times the cross section will minimise this risk. This reduces bending stress which increases service life.
To reduce installation difficulties and over-stretching, match the centreline perimeter of the groove with the centreline circumference of the O-Ring. For more information on O Ring installation and guidelines read our O-Ring Basics Handbook.
In certain circumstances the inside corner of the radii cannot be increased to the desired size. In this case, an alternative option is an O-Seal. This type of gasket has a round cross section similar to O-rings, but is designed to match the exact shape of the groove. This eliminates the risk that comes with bending stress at the corners.
Seals can be consolidated into a single O-Seal solution if multiple ports or openings in the face, or bolt holes to contour around. The installation process is simplified with all seals installed at the same time. This mitigates the risk of installing the incorrect seal material and allows for streamlining which in turn simplifies the amount of stock to be replenished during the assembly process.
Like O Rings, O-Seals are available in almost every material and engineered for optimum size and configuration for each unique application.
E & OE. M Barnwell Services endeavour to make sure that all content is correct. The information has been gathered from manufacturing partners.