[Barry_R]

Sometimes lost in the discussions lies the fact that gapless rings are not a new invention. They have been around in various overlap joints, bevel joints, and multirail designs since at least the 20s if not earlier.

The ring package is a dynamic sealing device moving at a high rate of speed under high pressures and at high temperatures. Not an easy thing to optimize or quantify. What works in one environment (say an air compressor) is not the best in another.

If you look at the wear pattern of rings at the gap you will find that they are not round. More & wider wear is evident at the tail end alongside the gap. They cut them after lapping so that the unit pressure at the gap is higher - this helps to stabilize the "tails".