This specification covers the requirements for two types (Types 8.8 and 10.9) of compressible-washer-type direct tension indicators, in nominal diameter sizes M16 through M36, capable of indicating the achievement of a specified minimum bolt tension in a structural bolt and are intended for installation under either a bolt head or a hardened washer. Steel materials used in the manufacture of direct tension indicators shall be designed, processed, heat treated, and protectively coated as specified. The direct tension indicators shall conform to required chemical composition, compression load, outside diameter, number of protrusions, thickness values, inside diameter, and protrusion tangential diameter values.

1.1 This specification covers the requirements for compressible-washer-type direct tension indicators, (DTIs) capable of indicating the achievement of a specified minimum tension in a structural bolting assembly.

1.2 Eight types of DTIs in nominal diameter sizes ¹/₂ through 1 ¹/₂ in. as well as M16 through M36 are covered:

1.2.1 Type 325-1—DTIs for use with Specification F3125 Grade A325 Type 1 bolts or Grade F1852 assemblies.

1.2.2 Type 325–3—DTIs for use with Specification F3125 Grade A325 Type 3 bolts or Grade F1852 Type 3 assemblies.

1.2.3 Type 490–1—DTIs for use with Specification F3125 Grade A490 Type 1 bolts or Grade F2280 assemblies.

1.2.4 Type 490–3—DTIs for use with Specification F3125 Grade A490 Type 3 bolts Grade F2280 Type 3 assemblies.

1.2.5 Type 8.8-1—DTIs for use with Specification F3125 Grade A325M Type 1 bolts.

1.2.6 Type 8.8-3—DTIs for use with Specification F3125 Grade A325M Type 3 bolts.

1.2.7 Type 10.9-1—DTIs for use with Specification F3125 Grade A490M Type 1 bolts.

1.2.8 Type 10.9-3—DTIs for use with Specification F3125 Grade A490M Type 3 bolts.

1.3 DTIs are intended for installation with the protrusions against a hardened surface such as a bolt head, a hardened nut, or a hardened washer. (See Research Council on Structural Connections: Specification for Structural Joints Using High–Strength Bolts.)

1.4 This specification provides for furnishing Type 3 DTIs to a Chemical Composition Requirement or a Corrosion Resistance Index (CRI) at the manufacturer’s discretion.

1.5 Terms used in this specification are defined in Terminology F1789 unless otherwise specified.

1.6 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.

1.7 The following precautionary statement pertains only to the test method portions, Section 10 and Appendix X1 of 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.

1.8 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.