ASME B18.2.1
Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)
Published by American Society of Mechanical Engineers (ASME)
The CFR incorporates ASME B18.2.1 by reference, which makes the edition it names part of the regulation. The CFR requires the edition it names, which may not be the newest. To enforce any other edition, the agency must publish the change in the Federal Register.
The edition the CFR requires
ASME B18.2.1-2012, issued April 24, 2013
As the CFR lists it: “ASME B18.2.1-2012, Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series), issued April 24, 2013 (“ASME B18.2.1”)”
How to read it
- Where to get itASME codes and standards ↗
A free or purchased copy may not be the edition the CFR names; check it against the edition above. Every incorporated standard can also be inspected at the National Archives (NARA) and at the agency named in the section that lists it.
ASME B18.2.1 is copyrighted by its publisher; RegKnot shows its title and the editions the CFR names, not its text. Read from the eCFR's incorporation-by-reference sections, current as of October 26, 2026. The regulation text governs. All standards the CFR requires.