5.1 The techniques described provide for the 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.

5.2 The Ultrasonic Pulse Echo technique is used to monitor changes in length of fasteners and as a tool for industrial quality control. Applications include fasteners used in turbines, petrochemical pressure vessels, aircraft, automotive manufacturing, general bolting within the nuclear industry, structural steel connections, and laboratory testing.

1.1 This practice covers a procedure for measuring changes in length of threaded bolts using the ultrasonic pulse-echo technique.

1.2 This procedure is normally intended for metal bolting 6.3 mm or more in nominal diameter with effective length-to-diameter ratios of 2:1 or greater.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.