PETOL™ PORTABLE HYDRA-TORK™ UNITS get the job done right by providing added safety, convenience, and speed in breaking out drill stem and drilling tools, as well as exactness in measuring torque. A controlled pressure relief valve on electric and gas power consoles allows the operator to adjust the working pressure for each job. When the set pressure is accomplished the system stops torquing. These portable units cover a wide range of diameter and torque requirements. The PETOL Special Chains used with the PETOL Drill Pipe Tongs on these units are equipped with heavy duty bolts which make it possible to quickly change from one O.D. size to another.