Scope
1.1 This specification covers the chemical, mechanical, and dimensional requirements for hardened steel Backup and Reaction washers for use with fasteners having nominal diameters of 1/2 in. through 3 in. and M14 through M80. These washers are intended for general-purpose mechanical and structural use with bolts, nuts, studs, DTIs, and other internally and externally threaded fasteners. These washers are suitable for use with fasteners covered in Specifications A354, A193/A193M, A194/A194M, A320/A320M, F959/F959M, A449, A563, A563M, and F3125.
1.2 The washers are designated by style denoting the shape, by type denoting the material, and by inch or metric dimensions.
1.2.1 The styles of washers covered are:
1.2.1.1 Reaction—Circular washers with a knurled surface on one side and a contoured outside diameter designed to couple with the installation tool.
1.2.1.2 Backup—Circular washers having a knurled surface on both sides.
1.2.2 The types of washers covered are:
1.2.2.1 Type 1—Medium Carbon or Medium Carbon Alloy Steel.
1.2.2.2 Type 3—Weathering steel. This specification provides for furnishing Type 3 to chemical composition or a Corrosion Index (CRI) of 6 or higher, at the supplier’s option.
1.3 The values stated in either inch-pound units for inch fasteners and SI units for metric fasteners and 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.
1.4 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.
1.5 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.
