The driller was using a hex tool wrench to remove a 2"" pipe fitting from the side inlet body. While pushing hard to break the fitting, the wrench slipped and EE's hand struck the drill mast. Wrong tool for the job was used. Driller had used a Hex tool wrench in place of a Pipe Wrench. Pipe wrenches ranging in size from 18 to 36"" were already on site. Incorrect Safety Glove worn.