Abstract: At approximately 11:00 a.m. on March 22, 2011, Employee #1, a sales representative with Surface Pumps, Inc., was assisting a field mechanic removing a positive displacement pump from its foundation at an oil well. A CoorsTek pulsation dampener (Serial Number 01011173A, Model Number 5085-3-F HNBR) was connected vertically to a pipe that ran horizontally, east to west. At the east end of the pipe, the dampener was connected to a block valve with bolts on a square flange that allowed for the pipe to swivel inside the flange. At the west end of the pipe, the dampener was welded to a flange that was bolted to the discharge end of the pump, keeping it from rotating. When the mechanic removed the bolts from this flange, the dampener rotated and struck Employee #1. He was hospitalized at Kern Medical Center for a compound left ankle fracture, a left elbow laceration, a fractured left clavicle, and torn cartilage in his sternum.