The National Board maintains four separate accreditation programs, issuing certificates of authorization and corresponding stamps and marks for the repair and alteration of boilers and pressure vessels (R), the repair/replacement of nuclear components (NR), the repair of pressure relief valves (VR), and the “test only” (T/O) in-service testing of pressure relief valves. National Board accredited programs — and their associated stamps and marks — are recognized worldwide. They are evidence that acceptable codes and standards are followed, jurisdictional and regulatory requirements are understood, and in-service repair and testing methods are applied satisfactorily. NBBI accreditation ensures users that boilers, pressure vessels, and pressure-retaining items have been repaired or replaced properly and will operate safely. 

Figure 2. National Board’s R stamp.
Figure 3. National Board’s T/O stamp.

The certificates are valid for three years from their date of issue. After a review, a recommendation to either issue, renew, or withhold the certificate of authorization will be made. Triennial reviews help ensure code compliance and that the quality program is updated, understood, and implemented as described within the organization’s written quality manual. A good quality control manual acts as a translation of the code language into the procedures applied on the shop floor. 

The R, NR, and VR stamps and T/O mark take up only a small section of a repair tag, but they represent the successful completion of a long and painstaking process on the part of the manufacturer, assembler, repairer, and/or testing organizations responsible for affixing them. Countless hours of hard work and dedication are behind every National Board stamp and mark, demonstrating to the owners, users, and inspectors of pressurized equipment that their safety and well-being are protected by a device that makes the grade. 

Below is an overview of the four accreditation programs NBBI offers. For more information, including program costs and applications, visit the accreditation section at NBBI.org. 

The National Board offers the R certificate of authorization and permission to use the R symbol stamp for the repair and/or alteration of boilers, pressure vessels, and other pressure-retaining items. Requirements are described in NB-415, “Accreditation of R Repair Organizations.” It is issued to organizations whose business is the repair and alteration of pressure-retaining items and to manufacturers and owner-users of pressure-retaining items. Organizations may be authorized to perform repairs only or repairs and alterations. The scope of the certificate of authorization can be for performing design only, metallic, or nonmetallic repairs and/or alterations. It may be issued for the shop only, field only, or in both shop and field environments. 

Figure 4. National Board’s VR stamp.

Organizations holding the R symbol stamp must maintain an inspection agreement with an authorized inspection agency (AIA). They must also have a written quality system that complies with the National Board Inspection Code (NBIC) and includes the expected scope of activities. A review of facilities will be conducted by a review team that includes a jurisdictional or National Board representative. Reviews include verifying the applicant has implemented a written quality system and has the latest mandatory edition of the NBIC and any applicable codes of construct ion appropriate for the intended scope of work. 

The National Board offers the NR certificate of authorization and permission to use the NR symbol stamp for the repair and/or replacement of nuclear components and pressure-retaining items. Requirements are described in NB-417, “Accreditation of NR Repair Organizations.” 

Organizations holding the NR symbol stamp must maintain an inspection agreement with an AIA. They must have a written quality system that complies with the NBIC and includes the expected scope of activities. A review of facilities will be conducted by a review team that includes a jurisdictional or National Board representative. Reviews include verifying the applicant has implemented a written quality system and has the latest mandatory edition of the NBIC, any applicable codes of construction appropriate for the intended scope of work, and a copy of the ASME Boiler and Pressure Vessel Code, Section XI. Organizations must also complete a pre-survey questionnaire at least 30 days in advance. 

The National Board offers the VR Certificate of Authorization and permission to use the VR symbol stamp for the repair of pressure relief valves. Requirements are described in NB-514, “Accreditation of VR Repair Organizations.” 

Organizations holding the VR symbol stamp must have a written quality system that complies with the NBIC and includes the expected scope of activities. A review of facilities will be conducted by a National Board representative. Reviews include verifying the applicant has implemented a written quality system and has the latest mandatory edition of the NBIC and any applicable codes of construction appropriate for the intended scope of work. 

An important part of that review is witnessing the repair of several sample pressure relief valves. An independent test for operation and capacity of these sample pressure relief valves will then be conducted at a National Board-accepted laboratory. The test is to verify the repaired valves meet applicable ASME code requirements for performance and capacity. 

The National Board offers the T/O certificate of authorization and permission to use the T/O mark for the in-service testing of pressure relief valves. Requirements are described in NB-528, “Accreditation of T/O Test Only Organizations.” 

Organizations holding the T/O mark must have a written quality system that complies with the NBIC and includes the expected scope of activities. A review of facilities will be conducted by a National Board representative. Reviews include verifying the applicant has implemented a written quality system and has the latest mandatory edition of the NBIC and any applicable codes of construction appropriate for the intended scope of work. 

An important part of that review is witnessing the testing and adjustment of several sample pressure relief valves. An independent test for operation of these sample-tested pressure relief valves will be conducted at a National Board-accepted laboratory. The test is to verify the tested valves meet applicable ASME code requirements for performance.

Related Accreditation Documents 

• NB-12, “Application for the National Board R Certificate of Authorization;” 

• NB-57, “The National Board and ASME Guide;”

• NB-163, “Application for the National Board NR Certificate of Authorization;” 

• NB-223, “Pre-Survey Questionnaire;” 

• NB-550, “Application for National Board VR and/or T/O Certificate of Authorization;” 

• NB-552, “Control Sheet;” 

• NB-553, “Applicant’s Guide for Implementation Demonstrations of Quality Control Systems for the Repair and Testing of Pressure Relief Valves;” and 

• NB-556, “VR and T/O Quality Manual Review Checklist.”     

This article originally appeared in the fall 2021 edition of the National Board’s BULLETIN. 

By Stephanie Campbell, publications editor, NBBI