This standard establishes a test procedure for nonmetallic resistant element prevailing-torque nuts having coarse threads, to determine their conformance with specified prevailing-torque requirements in nominal sizes #10 thru 1 in. intended for application temperatures of – 49°F to 250°F. Both partial (less than 360°) and full circumference (360°) element designs are included. It does not include nuts with adhesive coated threads which are included in IFI-160 or top insert two piece construction nuts which are included in IFI-100/107.

The prevailing-torque values given apply only to the combination of test conditions established in this standard. If conditions of any actual service/application differ from those included in this standard, the prevailing-torques may differ. Variables which may cause variation in prevailing-torque values include such conditions as length of thread engagement, thread tolerance and fit, speed of installation, materials, platings or coatings, and environment. Such values may only be determined by tests in actual application.

This standard is not concerned with dimensional features such as nut thickness or flanges; refer to IFI-100/107. Other mechanical or performance properties such as strength properties, corrosion resistance, sealing, and/or consistency of torque-to-tension relationships during assembly are not included in this specification. Such features and properties are covered in other standards and specifications and must be referenced when specifying a nut to ensure that all service conditions of the particular engineering application are properly met. For editorial convenience, the words, “Resistant Element Prevailing-Torque”, shall henceforth be referred to as “REPT”.