This specification covers two types of heat treated, steel, tension control bolt-nut-washer assemblies, also referred to as "sets," having a tensile strength of 150 to 173 ksi. These assemblies are capable of developing a minimum predetermined tension when installed by applying torque to the nut, while at the same time applying a counter torque to separate the spline end from the body of the bolt using an appropriate spline drive installation tool. The tension control bolts are designated by type denoting chemical composition as follows: type 1 - alloy steel, and type 3 - weathering steel. The chemical composition of the tension control bolts, nuts, and washers shall conform to the requirements specified. The assembly lot tension test shall be performed on fastener assemblies to determine the ability of the assembly to provide the required minimum tension. Tensile strength, proof load, hardness, and carburization/decarburization shall be tested to meet the requirements prescribed.

1.1 This specification covers two types of heat treated, steel, tension control bolt-nut-washer assemblies, also referred to as “sets,” having a tensile strength of 150 to 173 ksi. These assemblies are capable of developing a minimum predetermined tension when installed by applying torque to the nut, while at the same time applying a counter torque to separate the spline end from the body of the bolt using an appropriate spline drive installation tool.

1.2 An assembly consists of a tension control bolt with spline end (covered by this specification) and a suitable nut and washer covered by reference to applicable ASTM specifications.

1.3 The fastener assemblies are intended for use in structural connections. These connections, installation procedures, and the use of alternate design structural bolts are covered under the requirements of the “Specification for Structural Joints Using ASTM A 325 or A 490 Bolts”, approved by the Research Council on Structural Connections.

1.4 The assemblies are available with either round (button or dome) heads, heavy hex structural heads, or alternate design heads described in Section 11 , in sizes ½ to 1 ¹/₈ in. inclusive, in two types specified in Section 4.

1.5 Tension control bolts manufactured and marked in accordance with the requirements of Specification A 490, and conforming to the dimensional and other requirements of this specification, will be considered an acceptable alternate under this specification for two years following initial publication.

1.6 The following precautionary statement pertains only to the test method portions, Sections 15 and 16, 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.