NBBI NB23 Part 4-2025

First published in 1946, the National Board Inspection Code (NBIC) is an internationally recognized standard that governs and maintains rules for the installation, inspection, repair, and alteration of inservice pressure equipment. The NBIC is adopted into law by most US and Canadian jurisdictions. It is the basis for NBBI’s four accreditation programs (R, VR, NR, and T/O) and is utilized by more than 5,200 repair organizations in over 60 countries. The NBIC is recognized as a national standard by the American National Standards Institute (ANSI).

The NBIC is organized into four (4) Parts to coincide with specific post-construction activities involving pressure-retaining items.

Part 4, Pressure Relief Devices – This Part provides information and guidance to perform, verify, and document the installation, inspection, and repair of Pressure Relief Devices, including a supplemental section that contains specialized information, such as pressure margins, recommended repair practices, and test stand design details.