The "capture model" is predicated from the concept that sealing is accomplished by compression arising within a gasket between a knife edge and the retaining counter of a flange. Although it has been the rationale for the ConFlat (R) metal seal system, the credibility of the existing model has yet to be verified with respect to the seal mechanism, and hence, warrants reconsideration. In the present study, experimental results indicate that complete capture of the gasket is seldom obtained, and that capture is not a key factor in the sealing process. Numerical analyses of stress distribution in tightened gaskets show that capture rarely increases seal pressure, and has little influence on improving sealing reliability in the ConFlat system. Rather, the sealing ability of the ConFlat system seems to depend primarily on intense compressive stress on 20 degrees tapers of the seal surfaces.