Abstract: A method of closing an externally open segment of a fluid end of a reciprocating pump with a closure assembly includes inserting a non-circular closure element into a segment of a fluid end casing in a first direction while the non-circular closure element is disposed in a first orientation. The non-circular closure element is rotated to a second orientation that is angularly offset from the first orientation with respect to at least one axis of rotation. The non-circular closure element is further moved within the segment of the fluid end casing in a second direction that is opposite the first direction to cause the non-circular closure element to seat within the segment.

Abstract: A closure element for a fluid end of a reciprocating pump is installable within a segment of a casing of the fluid end to substantially close the segment. The closure element includes a main body that extends from an interior surface to an exterior surface, and at least a portion of the main body has a non-circular cross-sectional shape. A fluid end for the closure element may include a plurality of segments and at least a portion of at least one segment of the plurality of segments may have a non-circular cross-sectional shape configured to receive and secure a closure element with a non-circular cross-sectional shape.