ASTM F 2437/F 2437M:2017

1.1 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. 1.2 Direct tension indicators in inch sizes ¹/₄ through 2¹/₂ in. 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 ). 1.3.1 Style 1 DTIs are suitable for comparatively smaller bearing surfaces. Style 1 DTIs are available in Grades 5 and 8, which differ in the amount of tension they indicate at a prescribed gap (see Table 1 and Table 3 ). 1.3.2 Style 2 DTIs are suitable for comparatively large bearing surfaces. Style 2 DTIs are available in Grades 55 and 105, which differ in the amount of tension they indicate at a prescribed gap (see Table 1 and Table 3 ). (A) Compression load requirements establish the capability of the direct tension indicators to satisfy typical tension requirements for these grades. The user is not obliged to install fasteners and DTIs to these tensions, and is free to specify installation to lower tension values. When so specified, the DTI supplier shall provide a load-gap curve in accordance with 15.2 to enable the user to select the appropriate gap criteria for the intended target tension of the application. (B) The Mean compression load values for Grades 5 and 8 in nominal sizes up through 1-¹/₂ in are based upon 75% of the proof load for SAE J429 cap screws. For Grade 5 in nominal sizes over 1-¹/₂ in and up to 2-¹/₂ in inclusive, the mean compression load values are based on 75% of the proof load for ASTM A449. For grade 8 in nominal sizes over 1-¹/₂ in and up to 2-¹/₂ in inclusive, mean compression load values are based upon 75 % of the proof load for ASTM A354BD. © Mean compression load values for Grades 55 and 105 are based upon 60% of the yield strength for the matching fasteners on which they are used. (A) The Mean compression load values for property classes 8.8 and 10.9 are based upon 75% of the proof load for ISO 898-1 Bolts/Stud/Screws. (A) A Inch bolt and cap screw dimensions are designated in ASME B18.2.1 and metric bolt dimensions are designated in ISO 4014. (B) Inch nuts dimensions are designated in ASME B18.2.2 and metric nut dimensions are designated in ISO 4032. 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 Recommended Fasteners- Fasteners meeting the requirements of the standards referenced in Table 3 are considered compatible with the DTI grade or class listed. 1.6 The 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 may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.7 The following precautionary statement pertains only to the test method portions, Section 12 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. 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.

21.060.01