Abstract: A groove particularly designed and constructed for receiving an O-ring sealing member therein, and particularly for use on the closure member of a check valve. The groove comprises an annular recess provided on one face of the closure member, and having a cross-sectional configuration generally similar to a dovetail groove. One side of the groove is inwardly tapered to provide an undercut for the groove, and the opposite side of the groove is of an arcuate configuration complementary to the configuration of the outer periphery of the O-ring seating within the groove. When the O-ring is in a sealing position within the groove, there will be no scrubbing of the outer periphery of the O-ring against the inner periphery of the groove since the groove snugly receives the O-ring against the inner periphery of the groove since the groove snugly receives the O-ring against the arcuate sidewall thereof.