ASME B18.3.5M (1986)

Hexagon Socket Flat Countersunk Head Cap Screws (Metric Series)

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Annotation and contents

This standard is no longer an American National Standard or an ASME-approved standard. It is available for historical reference only.

This Standard contains the general and dimensional requirements for Metric Series Hexagon Socket Flat Countersunk Head Cap Screws of nominal sizes from 3 mm to 20 mm. Also included are appendices covering formulas for dimensions, part numbering system and preferred sizes for government use, and thread dimensions. The application of these screws is limited by their design as noted below. This product is designed and recommended for applications where a flush seating socket head screw is desired. Wrenchability is limited by the socket size and key engagement. Because of the head configuration, this product is not recommended where maximum fatigue resistance is required. The inclusion of dimensional data in this Standard is not intended to imply that all of the products described are stock production sizes. Consumers should consult with manufacturers concerning lists of stock production sizes. Screws purchased for government use shall conform to this Standard and to the requirements of Appendix II.