ASME · ANSI / ASME B18.21.1

ASME B18.21.1 Standard: Technical requirements for spring, tooth, and plain washers (inch series)

Technical requirements of the ASME B18.21.1 standard

This regulatory document specifies geometric parameters, physical and mechanical properties, and control test protocols for inch-series fasteners. The scope of the standard includes helical spring lock washers (size range from 0 to 3 inches), tooth lock washers (from 2 to 1 3/4 inches), and plain (flat) washers (from 0 to 3 inches). Specialists at EV Group China note that the presence of the standard in our database does not guarantee stock availability of all sizes; to verify current stock levels and delivery times, please contact our engineers.

Analysis of compliance with international standards

Currently, there are no direct equivalents in the ISO metric system for the specified types of fasteners.

Product classification

  • Helical spring washers: The standard covers a wide spectrum of cross-sections, including regular, heavy, extra-duty, and high-collar designs.
  • Tooth lock washers: These include modifications with internal, external, countersunk external tooth profiles, as well as combined internal/external teeth and specialized design types A and B.
  • Plain (flat) washers: The standard describes requirements for type A and B designs, as well as washers with a protective configuration.

Geometric parameters

All dimensional characteristics in the standard are presented in the imperial system. The specified values are basic and are applicable to products prior to the application of anti-corrosion or other protective coatings.

Terminology base and normative references

For the correct interpretation of terms and definitions related to the design features of washers, one should refer to the ASME B18.12 standard. A complete list of normative documents referenced by the current edition is presented in the appendix to the standard. EV Group China recommends using the latest editions of documents in your work, unless otherwise specified in the contract.