Tightening Your Threaded Bolts
If you want to prevent bolt failure and reduce scatter, you must understand how to correctly tighten the bolts. There are six popular methods for doing so, and each one can be used to control the preload.
Bolt Tensioner With this method, the torque that is needed to tighten the bolt is either calculated or pre-determined with a chart. Torque control tightening overcomes the friction that is normally associated with bolt tightening and calculating the amount of pressure that will be placed on the threads.
Angle Control Tightening-This method involves the use of pre-determined angles that are used to tighten bolts.
Bolt Stretch Method-The bolt stretch method involves the use a hydraulic device that causes an extension of the threaded bolt. If the pressure on the hydraulic device accurately controlled, the preload of the bolt will be controlled.
Bolt Tensioner is heated slowly either under fired, with the use of carbon elements, or with the use of a heating coil so it will expand. The nuts is placed using angle control, and as the bolt cools, it is forced to remain extended. In general, though, this method of tightening relies on the measurement of the extension of a bolt and bolts and washers that indicate how they should be loaded.