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Pressure Relief Group / Testing Laboratory

Part of the NBBI Technical Department, the Pressure Relief Group maintains and promotes programs related to overpressure protection of pressure equipment.

The NBBI Testing Laboratory plays an integral role in this process. The lab is an independent ASME-certified flow lab that tests pressure-relieving devices (PRDs) from valve manufacturers, assemblers, and repair facilities from around the world. Devices are tested to rigorous standards to demonstrate they will provide critical overpressure protection.

The Pressure Relief Group also maintains the following NBBI Capacity Certification programs: NB Mark for newly manufactured PRDs, VR Valve Repair program, and T/O Testing Organization program. NBBI serves as an ASME Designated organization, and Pressure Relief staff perform quality system reviews and audits on PRD manufacturers and assemblers whose devices bear the ASME V, UV, UD, HV and NV designators.

National Board Activities

  • Pressure Relief Device Certification
    The NB mark must be used by pressure relief device manufacturers and assemblers to identify pressure relief devices that have been certified by the National Board in accordance with NB-501, National Board Certification of Pressure Relief Devices.
  • VR Repair Program
    The National Board offers the Certificate of Authorization and VR Symbol Stamp for the repair of pressure relief valves. Requirements are included in the current mandatory edition of the National Board Inspection Code (NBIC), Part 4, and NB-514, Accreditation of VR Repair Organizations.
  • T/O Testing Program
    The National Board offers the Certificate of Authorization for use of the T/O symbol which indicates accreditation as a pressure relief valve Testing Organization. The program includes provisions for minor adjustments to restore valve performance. Requirements are based upon the current mandatory edition of the National Board Inspection Code (NBIC), Part 2, Part 4, and NB-528, Accreditation of T/O Test Only Organizations.
  • Investigation Testing
    The National Board supports members who request tests be conducted on pressure relief devices involved in boiler and pressure vessel accidents. This service is provided at no cost to the National Board member. Please contact Pressure Relief or Executive staff for more information.
  • Testing Laboratory
    As the world's only independent ASME certified flow laboratory, located north of Columbus, the National Board Testing Laboratory remains the leader in promoting accurate performance measurement of pressure relieving devices and the development of technical standards. Please click on the above Testing Laboratory link for additional information including test device size, pressure, and capacity limitations.


ASME Supporting Activities

  • ASME Designee – Shop Reviews
    The National Board is the ASME designee to conduct shop reviews of organizations for the ASME Certification mark with V, HVUV, and UD designators.
  • ASME Designee – Valve Selection and Test Witnessing
    Representatives from the National Board are assigned to visit company sites to select production sample valves for testing at National Board- and ASME- accepted labs.
  • ASME Designee – Laboratory Acceptance


Committee Participation

The National Board supports the following technical committees:

  • ASME Subcommittee on Safety Valve Requirements
  • ASME Subgroup on Pressure Relief Valves (Section III, Nuclear)
  • NBIC Subgroup Pressure Relief Devices
  • ISO/TC 185, international committee concerned with overpressure protection
  • U.S. Technical Advisory Group on ISO/TC 185


For more information regarding the National Board Pressure Relief Department,
please Contact Us.