This 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. These DTIs are intended for installation under a bolt or cap screw head, a hex nut, or against a hardened washer or other flat hardened surface. The following are two types of DTIs: Type 1 DTIs are suitable for comparatively large bearing surfaces and Type 2 DTIs are suitable for comparatively smaller bearing surfaces. DTIs shall have a configuration produced by extrusion, punching, pressing, or similar forming to permit a measurable decrease in thickness when placed in compression. The design shall be such that the degree of plastic deformation of the protrusions shall indicate the tension in a tightened cap screw, bolt, anchor, or stud. The process used for heat treatment of DTIs, if required, shall be through-hardening by heating to a temperature above the upper transformation temperature, quenching in oil, and then tempering by reheating to a suitable temperature to attain desired mechanical/performance properties. Protective coatings, platings, or finishes may be applied on the DTIs if specified. Compression load and hardness of the DTIs shall be determined by performing mechanical tests.

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

1.2 Direct tension indicators in nominal diameter sizes ¼ through 2 ½ in. are covered.

1.3 There are two Types of DTIs covered by this specification, Type 1 and Type 2.

1.3.1 Type 1 DTIs are suitable for comparatively large bearing surfaces. Type 1 DTIs are available in Grades 55 and 105, which differ in the amount of tension they indicate at a prescribed gap (see Table 1).

1.3.2 Type 2 DTIs are suitable for comparatively smaller bearing surfaces. Type 2 DTIs are available in Grades 5 and 8, which differ in the amount of tension they indicate at a prescribed gap (see Table 1).

1.4 Direct 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.

1.5 The following precautionary statement pertains only to the test method portions, Section 12 and Appendix XI 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 and health practices and determine the applicability of regulatory limitations prior to use.