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1.1 This specification covers the chemical and mechanical requirements of quenched and tempered steel bolts, in nominal thread diameters M16 to M36, inch. These bolts are intended for use in structural joints that are comparable to those made under the Specification for Structural Joints Using ASTM A325 or A490 Bolts issued by the Research Council on Structural Connections of the Engineering Foundation. The various types of bolts covered by this specification are:

1.1.1 Type 1- Bolts made of alloy steel, supplied in nominal thread diameters M16 to M36, inclusive.

1.1.2 Type 2- Bolts made from what is generally described as low-carbon martensite steel, supplied in nominal thread diameters M16 to M24 inclusive.

1.1.3 Type 3- Bolts in nominal thread diameters M16 to M36, inclusive, having atmospheric corrosion resistance and weathering characteristics comparable to that of the steels covered in Specifications A588/A588M, A242/A242M, and A709/A709M. The atmospheric corrosion resistance of these steels is substantially better than that of carbon steel with or without copper addition. See 6.3. When properly exposed to the atmosphere, these steels can be used bare (uncoated) for many applications.

1.2 Unless otherwise specified, all nuts used on these bolts shall conform to the requirements of Specification A563M, shall be heavy hex, and shall be of the class and surface finish for each type of bolt as follows:

Bolt Type and Finish Nut Class and Finish 1 and 2, plain (noncoated) 10S, 1053, plain 3, plain 10S3, plain

1.3 Unless otherwise specified, all washers used on these bolts shall conform to the requirements of Specification F436M and shall be of a surface finish for each type of bolt as follows:

Bolt Type and Finish Washer Finish 1 and 2, plain (uncoated) plain (uncoated) 3, plain weathering steel, plain

1.4 This specification provides that heavy hex structural bolts and heavy hex nuts shall be furnished unless other dimensional requirements are stipulated in the purchase inquiry and order.

Note 1-For quenched and tempered steel bolts, studs, and other externally threaded fasteners with nominal thread diameters larger than M36, but with similar mechanical properties, refer to class 10.9 of Specification F568. Note 2-This specification is the metric companion of Specification A490.