The techniques described provide for the indirect measurement of change in length of a fastener. Such measurements are made from one end of the specimen without requiring access to the rear surface.

The equipment is field portable and should be used in the manner prescribed by the manufacturer. Common uses include monitoring changes in length of fasteners and as a tool for industrial quality control. Current applications include fasteners used in turbines, petrochemical pressure vessels, aircraft, automotive manufacturing, general bolting within the nuclear industry, structural steel connections, laboratory testing, and so forth.

1.1 This practice covers a procedure for measuring changes in length of threaded fasteners using conventional ultrasonic pulse-echo bolt-measuring instrumentation which has been properly calibrated.

1.2 This procedure is normally intended for metal bolting 0.25 in. (6.4 mm) or more in nominal diameter with effective length-to-diameter ratios of 2:1 or greater.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.