Adding on to that, tensioning bolts using torque is convenient and inexpensive but not very accurate at all. Some data reproduced in Shigley's Mechanical Engine

Adding on to that, tensioning bolts using torque is convenient and inexpensive but not very accurate at all. Some data reproduced in Shigley's Mechanical Engineering Design showed a +/- 30% variation in tension for properly torqued bolts, if my memory is correct. Emphasis on properly torqued: in the field threads or bolt heads might be dirty, or torque wrenches might be out of calibration, adding even more uncertainty.