Once the cracked carbon ring starts to wear, high pressure and high speed leaking steam will enter the bearing housing. Traditional labyrinth seals have proven ineffective in many cases, and only solidly designed bearing protector seals can effectively prevent leaking steam from entering. The bearing case protector seals are designed for steam turbines. It contains a small and large diameter dynamic O-ring. The bearing protector seal is stable and does not sway on the shaft; it is also field-modifiable.

When the turbine stops, the outside of the two dynamic O-rings will move back to their rest position. When stationary, the outer O-ring contracts and contacts the larger cross-section O-ring. In this design, a larger cross-section O-ring contacts a larger contour area.

Because contact pressure is equal to force divided by area, a good design goal is to reduce pressure. In outdated configurations, contact with the sharp edges of the O-ring groove can damage the O-ring, and fragments of O-ring material can contaminate the process lubricant.

Increase to a good bearing environment

Fortunately, concerns about the time taken to add to the bearing protector seal have been resolved. Modern products fit the space previously occupied by lip seals.

In 2009, when a Dutch refinery requested a bearing protector seal for one of its steam turbines, no modification of existing equipment was allowed.