Abstract: A method of forming a flat plate swing valve shell from a commercially available forged or swaged pressure vessel head having circular sections in horizontal planes and elliptic sections in vertical planes. The shell is formed by cutting the head along a vertical axis to form two halves, rotating the halves outwardly with respect to each other and repositioning them so their original base edges are juxtaposed and the two halves form a continuous enclosure having an open base and which has elliptic sections in both vertical and horizontal planes, and welding the two halves along said base edges to form a unitary valve shell.