Abstract: At approximately 8:00 a.m. on January 13, 2010, Employee #1 was working on a natural gas service rig, tightening a safety valve onto the rig's 2.38-inch metal tubing, using a 36-inch wrench. Earlier in the day, Employee #1 and a coworker laid metal tubing on the ground for placement in the drill hole. Simultaneously, Employee #1 and his coworker positioned a Texas Iron Work (TIW) safety valve on the end of the metal tubing a few feet above from the rig floor. Employee #1 then began to attach the TIW safety valve onto the end of the metal tubing by hand tightening it to the tubing's thread. After hand tightening the TIW safety valve, Employee #1 and his coworker obtained two 36-inch monkey wrenches, which they used to complete tightening the TIW safety valve to the tubing. As Employee #1's right leg was over the wrench and he used his right hand to grasped the outer side of the wrench, he jumped (or bounced) 6 inches off the drill rig floor onto the wrenches handle to gain extra leverage in tightening the TIW safety valve. He continued to successfully jump about three more times while tightening the valve, but on the fourth jump the wrench slipped off of the metal tubing and dropped to the rig floor. Employee #1's left leg then struck the rig floor, where the wrench had fallen, fracturing his leg. Employee #1 was hospitalized and treated for his injury. The accident investigation revealed that Employee #1 was improperly using the wrench by "jumping" on wrench to tighten the TIW safety valve, and supervisors failed to stop such an unsafe practice. No citations were issued to the employer.