This document is a summary of Bolt Tensioning（本文档是螺栓张紧的一个总结）.pdf

Phone: +61 (0) 402 731 563 Fax: +61 (8) 9457 8642 Email: info@ Website: If you want to learn more about best practice machinery maintenance, or world class mechanical equipment maintenance and installation practices, follow the link to our Online Store and see the Training presentations and Books there… /store/machinery-maintenance-and- inspection/store-machinery-maintenance.html This document is a summary of ... Bolt Tensioning A bolt and nut are designed to act together as the internal threaded fastener (nut) is tightened onto the externally threaded fastener (bolt). The bolt is forced to stretch and elongate. This stretching/elongation is maintained by the head of the bolt and the nut on the joint thereby maintaining the joint at the desired tension (Bolt tensioning). As a rule, the joint will have been designed with sufficient fastener to apply the required clamp load at 65% of the fastener proof load stress figure i.e. well below the fastener’s yield point. Yield point or yield strength It is defined as the load that is necessary to stretch the fastener to the point where, after the load is removed, the bolt will not return to its original or previous length. It has moved from being elastic to plastic behaviour. In order for the fastener to incur a longer length part of bolt donates material. This will come from the threads, which are the weakest part of the bolt. A section of the threaded portion of the bolt wall suffers a reduction of area and will “neck out”, creating a “dog bone” appearance. The change in stress area makes the bolt considerably weaker and as the bolt is str