ASTM F2437/F2437M-17(2023)

1.1This specification covers the requirements for carbon and alloy steel compressible-washer-type direct tension indicators (DTIs) capable of indicating a specified bolt tension in cap screws, bolts, anchors, and studs.

1.2Direct tension indicators in inch sizes ¹/₄through 2¹/₂in. and metric sizes M6 and M72 are covered.

1.3 Direct tension indicators have two styles and four grades for inch fasteners, Grades 5, 8, 55, and 105, and two property classes for metric fasteners, property classes 8.8 and 10.9 each of which differ in their compressive load requirements at a given gap (see Table 1 and Table 2).

1.4Direct tension indicators are intended for installation under a bolt or cap screw head, a hex nut, or against a hardened washer or other flat hardened surface.

1.5Recommended Fasteners-Fasteners meeting the requirements of the standards referenced in Table 3 are considered compatible with the DTI grade or class listed.

1.6The values stated for Inch DTIs are expressed in inch-pound units and for Metric DTIs values are expressed in SI units. 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.

1.7The following precautionary statement pertains only to the test method portions, Section 12of this 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.

1.8This 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.