NBIC NB23-4 2025, Part 4 of the National Board Inspection Code, provides requirements, information, and guidance for pressure relief devices used with boilers, pressure vessels, piping systems, and related pressure-retaining equipment. This edition addresses general and administrative requirements, installation practices, in-service inspection, testing and operational inspection, repair of pressure relief valves, accreditation requirements for test-only and VR repair organizations, and supplemental procedures for specialized pressure relief device applications.
The document is intended for manufacturers, jurisdictions, inspectors, owner-users, installers, contractors, repair organizations, and other professionals involved in post-construction activities for pressure relief devices. It includes detailed sections on device requirements, set pressure, capacity, discharge piping, inspection and testing intervals, quality system requirements, nameplate and stamping provisions, repair procedures, metrication policy, technical inquiries, glossary terms, interpretations, and index material.
Application Scope: Applicable to post-construction installation, inspection, testing, and repair activities involving pressure relief devices under the 2025 National Board Inspection Code, subject to jurisdictional requirements and other referenced codes or standards.
