Torque and Tension are two different methods that are trying to accomplish the same end goal – proper clamp load. Torque uses force to turn the nut which in-turn causes the stretch of the bolt to increase. After turning the nut to a set value, this should meet the engineering spec to achieve proper clamp load/force on your fastener. A bolt tensioner stretches the bolt first as opposed to turning/torquing the nut. Once the proper load has been achieved from the bolt tensioner, the nuts are turned hand tight. After all nuts have been secured, the pressure from the hydraulic tensioner is released back into the pump.