The oil-film-lubricated mechanical face seal described here is a hydrodynamically lubricated, noncontacting, mechanical face seal with zero leakage. Oil the basis of systematic theoretical analyses, research on design methods, and experimental investigations, many field applications have been made. The experimental investigations include test rig development; longtime high-speed running tests; frequent start-up and shut-down tests; measurements of the seal leakage, face temperature, and characteristics of the self-circulating screw pump; observation, measurement, and solution of interface wear, and so on. Until now, this new seal design has been successfully applied in more than 40 high-speed turbocompressors in the oil refinery and petrochemical industries, achieving zero leakage and long operation. These seals are all designed with diffferent face spiral-groove patterns, structure arrangements, and supporting systems.