While operating a grinder in a Department of Defense (“DOD”) welding shop in Barstow, California, one of Respondent’s employees was severely injured when the grinding stone he was using exploded. (Tr. 156). Although he was using proper protective equipment, the employee suffered a severe laceration to his head and a concussion that put him out of work for nearly six months.2 (Tr. 58–59, 510; Ex. C-17). Subsequent investigation revealed the employee used a grinding stone with an RPM (revolutions per minute) rating that did not match the RPM rating of the grinder. (Stip. No. 10; Tr. 272; Ex. C-9).