ASME B16.5
Pipe Flanges and Flanged Fittings, NPS 1/2 Through NPS 24 Metric/Inch Standard, Issued
Published by American Society of Mechanical Engineers (ASME)
The CFR incorporates ASME B16.5 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 4 editions the CFR requires
Different parts name different editions; each applies where its part says so. Newest first.
ASME B16.5-2020, January 29, 2021
As the CFR lists it: “ASME B16.5-2020, Pipe Flanges and Flanged Fittings, NPS 1/2 Through NPS 24 Metric/Inch Standard, Issued January 29, 2021”
- Listed in 33 CFR 127.003(b)(1); required by33 CFR 127.1102 ↗
ASME B16.5-2017, issued November 20, 2017
As the CFR lists it: “ASME B16.5-2017, Pipe Flanges and Flanged Fittings, NPS 1/2 Through NPS 24 Metric/Inch Standard, issued November 20, 2017, (“ASME B16.5”)”
ANSI B16.5, 1988
As the CFR lists it: “ANSI B16.5, Steel Pipe Flanges and Flanged Fittings, 1988”
- Listed in 46 CFR 153.4(b)(1); required by46 CFR 153.940 ↗
Listed as: “ANSI B16.5, Pipe Flanges and Flanged Fittings, 1988”
ANSI B16.5, 1981
As the CFR lists it: “ANSI B16.5, Steel Pipe Flanges and Flanged Fittings, 1981”
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 B16.5 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.