Annular seal element and dovetail groove

A seal element for installation in an annular groove is disclosed. The groove has a mouth, first and second side walls, and a base wall axially extending between the side walls. The side walls extend toward each other as each side wall respectively approaches the mouth to form a dove-tail shape in toroidal cross-section. Within the groove, the first side wall meets the base wall at a generally inwardly rounded surface. The seal element is annularly shaped and has an external seal surface that in toroidal cross-section includes first and second arcual portions and a pair of flashing points. The first arcual portion contacts the side walls and the base wall and partially protrudes through the mouth of the groove. The second arcual portion is complementarily received by a portion of the inwardly rounded surface of the groove. The pair of mold flashing points are oppositely situated on the external seal surface, and each flashing point is positioned on a part of the external seal surface located away from a sealed fluid.