Patent ID: 9249798
Filing Date: 2016-02-02
CPC Classification: F04B,Y10T

Claim Text:
1. A two-step autofrettage process for enhancing the fatigue resistance of a multi-cylinder reciprocating pump fluid end used to pump well stimulation fluids downhole, the process comprising: arranging at least three fluid end cylinders in a linear fashion; determining an optimal autofrettage pressure for a central cylinder of the at least three fluid end cylinders; determining an optimal autofrettage pressure for the remaining at least two side fluid end cylinders; autofrettaging the central cylinder separately from the remaining cylinders at the optimal central cylinder autofrettage pressure; autofrettaging the remaining at least two side fluid end cylinders without autofrettaging said central cylinder at the optimal side fluid end cylinder autofrettage pressure; wherein said autofrettaging the remaining at least two side fluid end cylinders is performed concurrently, yet independently of said autofrettaging of the central cylinder.