TM 9-243TYPES AND USES - ContinuedPIPE WRENCHESThere are three basic types of pipe wrenches, thestillson wrench, the strap wrench, and the chain wrench.They are all used to connect or break pipe joints or toturn cylindrical parts.The stillson pipe wrench has a fixed jaw which is on theend of the handle and an adjustable jaw at the top of thewrench. Adjustment is made by turning a knurledadjusting screw which moves the jaw. Always pull thepipe fitting towards the fixed jaw. The serrated (grooved)jaws of the stillson wrench will mar soft pipe.Strap pipe wrenches have a leather or canvas strapwhich is attached to the handle. The strap is loopedaround the pipe and back through the handle to grip thepipe. The strap pipe wrench will not scratch the surfaceof the pipe.Chain pipe wrenches have a section of bicycle-typechain permanently attached to the handle. The uppersection of the head has teeth which mate with the links ofthe chain. The chain is wrapped around the pipe andpulled over the head section of the wrench to grip thepipe. Chain pipe wrenches will scratch the surface of thepipe.T O R Q U E W R E N C H E STorque wrenches are designed to measure the spe-cific degree of tightness of nuts or bolts. Torquewrenches are considered precision instruments andtherefore must be calibrated at regular intervals.Torque wrenches are used for final tightening of nutsor bolts. Torque wrenches are normally calibrated ina right-hand direction only. If a unit is required toperform torquing operations in a left-hand direction,they must request that the supporting calibration fa-cility calibrate the torque wrench in both directions.A dial torque wrench has a head which contains thedrive element and a dial for reading the exact amount oftorque.Change 125-11
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