US Patent 10273954 Fluid end of a reciprocating pump with reduced stress

A fluid end of a pump includes a body that defines a suction bore, a discharge bore, and a plunger bore. A first central longitudinal axis extends through the suction bore, the discharge bore, or both. A second central longitudinal axis extends through the plunger bore. A chamber is defined at an intersection between the suction bore, the discharge bore, and the plunger bore. An interior surface of the body that at least partially defines the chamber comprises a first wall portion that is at least partially planar and oriented at an angle that is less than or equal to 15° from perpendicular to the first central longitudinal axis.