scope:

This standard establishes conformance test procedures for the locking ability performance of prevailing torque type lock screws which utilize a nonmetallic locking element (hereinafter called lock screw).

NOTE: LOCK is a generic term used to identify the externally threaded products coved in this standard. The terms lock and locking are not intended to imply an indefinite permanency of fixity.

The prevailing torque values given in this standard are conformance requirements for lock screws and apply only to the combination of test conditions described in the locking ability test procedures 4.2 or 4.3. If the conditions of the actual service application differ from those of 4.2 or 4.3 (e.g., internally thread 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 lock screw in its application.

This standard is not concerned with dimensional features such as head styles, or with other mechanical or performance capabilities such as strength properties, corrosion resistance, sealing, suitability for use in low temperatures, or temperatures above 125°C, and/or consistency of torque-to-tension relationships during assembly. Such features and properties are covered in other standards and specifications and must be referenced when specifying a lock screw to assure that all of the service conditions of the particular engineering application are properly met.