ASME International

Screw and Washer Assemblies - Sems (Inch Series)
 N B18.13A

Annotation

(a) This Standard covers general and dimensional data pertinent to the various types of screw and captive washer assemblies, otherwise known as sems. The word sems is recognized in the United States as a generic term applicable to screw and washer assemblies.

Also included in this Standard are appendices to illustrate the relative proportions of plain and conical washer sems and provide documentation on the washer dimensions for sems with screw types and head styles that have been relegated to "not recommended for new design" status.

(b) This Standard does not duplicate the general and dimensional data pertaining to components of sems as found in the following standards:

ASME B18.2.1 Square and Hex Bolts and Screws (Inch Series)

ASME B18.6.3 Machine Screws and Machine Screw Nuts

ASME B18.6.4 Thread Forming and Thread Cutting Tapping Screws and Metallic Drive Screws (Inch Series)

ASME B18.21.1 Lock Washers

ASME B18.22.1 Plain Washers

SAE 5773 Conical Spring Washers

NOTE: The word lock, which appears in the names of products in this Standard, is a generic term historically associated with their identification and is not intended to imply an indefinite fixity in attachments where the fasteners are used.

(c) Copies of referenced standards may be obtained from the following: SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001; ANSI, 11 West 42nd Street, New York, NY 10036-8002; ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959; ASME, 22 Law Drive, Box 2300, Fairfield, NJ 07007-2300, (800) 843-2763.