Measurement of prevail torques 05 January 2023

For the long-term durability of a bolted connection, it is of the utmost importance to know the tendency for embedment and relaxation under stress, which is what REC Fastening is able to measure using its high precision electric measurement wrenches of the FAST portable type.

Within its test laboratory REC Fastening GmbH uses its FAST portable to analyse the embedment and relaxation tendency of fastener joints. With an accuracy of 0.5%, and an angular resolution of 0.025 degrees, up to 10,000 pairs of measured values per second can be recorded and evaluated.

In order to be able to make a statement about the tendency for embedment and relaxation of the fastener joint, the original components are first assembled using a defined assembly strategy. During assembly, the tightening torque produces a certain preload force into the fastener joint. Subsequently, the bolted joint can be affected (loaded) by thermal, dynamic or environmental influences. After the treatment, the fastener joint is subjected to a high precision further tightening torque test. The drop in the measured prevail torque (Mw) in relation to the initiated assembly torque (MA) is a measure of the reduction in the preload force and thus a measure of the tendency of the bolted joint for embedment and relaxation.

“The high-resolution, handheld measuring wrench for torque drive angle testing was developed for the simple and precise detection of further tightening torques and loosening torques,” explains REC Fastening. “Combined with the REC® MESStec proWIN software, the FAST portable is an optimal analysis system for assembly processes in fastener technology, both for use in development and for process validation.” 

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Will Lowry Content Director t: +44 (0) 1727 743 888


Will joined Fastener + Fixing Magazine in 2007 and over the last 15 years has experienced every facet of the fastener sector - interviewing key figures within the industry and visiting leading companies and exhibitions around the globe.

Will manages the content strategy across all platforms and is the guardian for the high editorial standards that the Magazine is renowned.