IFI-524, Test Procedure for the Performance of Metric Nonmetallic Resistant Element Prevailing-Torque Screws


Issued 1982; Revised 2002, Reaffirmed 2013



This standard establishes a conformance test procedure for the performance of metric Nonmetallic Resistant Element Type Prevailing-Torque Screws (hereinafter called REPT screw), in nominal thread diameters M1.6 thru M36. The prevailing-torque values given in this standard are conformance requirements of test conditions described in the performance test procedure (5.1). If the conditions of the actual service application differ from those of 5.1 (e.g., internally threaded hole in a different material, length of thread engagement, class of internal thread tolerance, speed of driving, different plating or coating on screw or mating part), the prevailing-torque values may differ. Such values can only be determined through testing the REPT screw in its specific application. This standard is not concerned with dimensional features such as head styles, or with performance capabilities such as strength properties, corrosion resistance, sealing, suitability for use in high or low temperatures, and/or consistency of torque-to-tension relationships during assembly.