The HELICOFLEX® DELTA seal is a member of the HELICOFLEX® family of spring-energized seals. It is a unique sealing solution using two small ridges or “Deltas” on the face of the seal. The load required to plastically deform the jacket material is greatly reduced by concentrating the compression load on the Deltas. The resulting high-contact stress in the seal track makes the HELICOFLEX® DELTA metal seal an excellent choice for ultra-high vacuum applications that require ultra-low Helium leak rates. There is typically no risk of damaging the flange sealing surfaces as long as the minimum hardness requirements are maintained.