This specification covers externally threaded bolts, studs, and cap screws called fasteners, capable of indicating clamping forces up to yield strength during the tightening process or post installation residual tension, or both. Load-indicating fasteners utilize mechanical, electronic, or ultrasonic means to indicate fastener tension. These fasteners provide a means to verify the desired clamp load in critical applications upon installation and in service. This specification covers the following four different types of load-indicating fasteners: mechanical dial type (MT); electronic type (ET); strain gauge type (ST); and ultrasonic type (UT). Tension test shall be performed to conform to the chemical and mechanical requirements specified.

1.1 This specification covers externally threaded bolts, studs, and cap screws, herein called fasteners, capable of indicating clamping forces up to yield strength during the tightening process or post installation residual tension, or both. Load-indicating fasteners utilize a variety of sensor types to indicate fastener tension. This specification outlines the various types of load indication technologies available and defines their performance requirements.

1.2 This specification covers fastener diameters ¹/₄ to 7 in. [M6 to M180] inclusive. Fasteners are manufactured from a variety of material types and grades. All fastener materials shall be defined by a governing engineering standard or specification for strength and performance values (see 6.1). Fasteners governed by this specification shall maintain traceability of material test records throughout the manufacturing process to verify conformance with the applicable fastener standards.

1.3 These fasteners provide a means to verify the desired clamp load in critical applications upon installation and in service.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.5 The following precautionary statement pertains only to the test method portion, Section 11, of the specification: 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.

1.6 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.