The 2021 National Board Inspection Code Part 4 is a technical PDF reference for pressure relief devices used with boilers, pressure vessels, piping systems, heat exchangers, and related equipment. It covers installation requirements, in-service inspection, testing, operational inspection, repairs, welding, heat treatment, stamping, accreditation programs, personnel qualification, metrication, technical inquiries, approved interpretations, and recommended procedures for specialized pressure relief device applications.
Developed for manufacturers, jurisdictions, inspectors, owner-users, installers, contractors, repair organizations, and other professionals involved in pressure equipment safety, this edition supports consistent post-construction activities and documentation for pressure-retaining items.
Application Scope: Professional use in pressure equipment installation, inspection, testing, repair, alteration, accreditation, and safety compliance activities involving pressure relief devices.
