The spring-energized metal U-ring is a high-performance evolution of the axial seal, integrating a metallic "U" substrate with an internal spring-energized core. This design provides the necessary seating force to seal against rough surfaces while accommodating limited joint motion or sliding.

By default, these seals are system pressure energized for axial pressure applications. While they require a higher bolting load, they offer superior spring-back properties and reliability in extreme conditions ranging from cryogenic temperatures to 800°C.