This case-study, covering the period 2012 – 2015, describes how a "Change in the Safety Culture" process that took place in workshops which were manufacturing, assembling, and repairing valves used in the fracturing of unconventional reservoirs. The need for action was clearly demonstrated by an unacceptable 2012 Total Recordable Incident Rate of 13.99. A situational assessment, executed by late 2012, showed that the prevailing safety culture was one that accepted as inevitable that "accidents happened, happen, and will continue to happen." Corrective and proactive actions were outlined and implemented in order to change that state of mind. The ultimate and most important key performance indicator (KPI) chosen to monitor the "Change in the Safety Culture" was the rolling 12-month total recordable incident rate (Rol12Mo TRIR). From the period of May 2013 thru the end of 2015 the trend in Rol12Mo TRIR was almost continually downward. The last OSHA recordable injury occurred in November 2014; over the subsequent 13 months in a row, not a single recordable injury was registered.