Back To Top
Products & Services

Marks That Matter: PRVs & Certification Symbols

March 11, 2020

 If you’ve ever worked with pressure relief valves (PRVs), you’ve likely seen the images in the graphic below. Do you know what they mean?

Click on the image below to try our PRV Certification Marks Quiz. Find out how much you know about the certification marks on pressure relief devices.

Th "NB" symbol  is a stamp that means an organization has earned its certification from the National Board of Boiler and Pressure Vessel Inspectors to repair pressure relief valves.

The "ASME" symbol  is a certification mark from the National Board and the American Society of Mechanical Engineers. It indicates that a pressure relief device is compliant with the ASME Boiler and Pressure Vessel Codes (BPVCs).

Why do certification marks and symbols on pressure relief devices matter?

The improper installation of pressure relief devices can have dire consequences, causing unnecessary safety risks, and delaying operations while they are replaced or repaired. PRVs are typically one of the last lines of defense in an upset condition. To ensure that PRVs relieve and flow properly, the ASME and the National Board certify all PRV assembly programs, testing facilities, and even technicians. When you see marks and symbols on your pressure relief devices, it means that your device is certified safe because it came from a National Board and/or ASME certified organization.

The National Board sets the industry standards for pressure relief devices and is responsible for markings and symbols on their pressure relief devices are those that:

  1. Successfully complete ASME & National Board programs,
  2. Receive and maintain successful audits of their processes, and
  3. Receive accreditation.

That’s why the symbols stamped on PRVs and other pressure relief devices matter.


What do the symbols look like, and what do they stand for?

 The five symbols in the above graphic above are issued by the ASME and National Board. There are others, and you may see a few different variations from time to time. Each of them denotes a specific certification:

ASME Boiler and Pressure Vessel Code Certificate of Authorization Program The American Society of Mechanical Engineers offers Certificates of Authorization for the construction of new pressure-retaining equipment to various sections of the ASME Boiler and Pressure Vessel Code – Section I; IV; VIII, Divisions 1, 2, & 3; X; and XII. A

The National Board offers the Certificate of Authorization and the “R” symbol stamp for the repair and/or alteration of boilers, pressure vessels, and other pressure-retaining items.

The National Board offers the Certificate of Authorization and “NR” symbol stamp for the repair and replacement actives for nuclear items.

The National Board offers the Certificate of Authorization and VR Stamp for the repair of pressure relief valves.

The ASME Single Certification mark indicates that an organization has followed all aspects of the ASME codes and standards, meeting all requirements of the Conformity Assessment certification program. The ASME certification mark is stamped onto devices, paired with one of 8 designators from the National Board: V, UV, UV3, UD, HV, NV, TV, depending on which program they’ve completed. For example, at Vinson Process Controls, we are UV Assembly certified, meaning we successfully completed the National Board’s UV Assembly certification program. Because we are a certified PRV assembler, our customers know that the pressure relief devices they receive from us are compliant with the ASME Boiler and Pressure Vessel Codes (BPVCs). The mark for a UV assembly certified company has the ASME single certification mark paired with the UV designator from the national board.


Did You Know:

Vinson is UV Assembly Certified

 Why is it important that you purchase PRV devices from an ASME and National Board UV- Certified Assembler?

The simple answer? Safety. However, there’s a bit more to safety than you might think. In order to ensure safe operation, organizations like the ASME and National Board set firm standards and require the completion of specific programs to attain certification. These programs are rigorous, and the UV Assembly Program is no exception.  It’s designed to be very stringent, as it ensures consistency in the capabilities and functionality of all components in the PRV assembly process. Ideally, a PRV should be procured from a certified assembler that is also able to test and repair the device if necessary. Unfortunately, this is a tall order that not all suppliers are able to.

Vinson Process Controls has the capabilities and credentials required to assemble, test and repair pressure relief devices. In order to better serve our customers, we earned the certifications for the UV (assembly program), VR (valve repair) and T/O (testing only) certifications from the ASME and the National Board. We take the guesswork out of PRV procuring and maintenance so that our customers can relax and reap the benefits.


What are the benefits of purchasing PRV devices from an ASME and National Board-Certified supplier? 

Purchasing pressure relief devices from a certified supplier, like Vinson, benefits customers in three ways:

  1. Flexible Delivery,
  2. Dependable quality,
  3. Competitive pricing.


Flexible Delivery

How does the UV Assembly Program allow for flexible delivery?

As a UV-certified assembler, Vinson has invested in stocking Anderson Greenwood™ and Crosby™ relief valves for faster lead times. We have a wide range of options for our customers, including same-day service, when required.  The vast majority of Vinson’s relief valve inventory is in the portable 81P valves and pilot operated valves. Apart from the combined inventory we share with Emerson, we also have access to shared inventory across all 21 of Emerson’s Impact Partners. We are proud to say that all valves assembled in our Carrolton Valve Center have met or exceeded expected shipping dates.

Dependable Quality

Faster lead times are great, but what about quality?

In addition to faster lead times, our customers can maintain confidence that the products shipping from Vinson are of the same quality as those shipping directly from Emerson’s factory. The ASME, the National Board and Emerson audit all shops, quality control processes, techniques, and valves, before and after awarding certifications.  Vinson will continue to receive audits to ensure that we are meeting or exceeding expectations over time. Our adhesion to our quality control manual means that all valves assembled by Vinson have the same factory warranty as if they were assembled in Emerson’s production line.


Competitive Pricing       

How much more does it cost for fast, quality equipment?

As a part of the Emerson Impact Partner Network, Vinson is one of the primary points of contact for direct sales of Anderson Greenwood™ and Crosby™. We are a certified UV assembler, also offering valve repair and testing services. We can offer you quotes for both repair and replacement options.  Because of this unique status, Vinson can offer competitive pricing.

Vinson is proud to be an ASME and National Board UV and VR certified supplier. We are excited about our ability to offer our customers flexible delivery and quality products, all at a competitive rate. Our partnership with Emerson™ and the Emerson Impact Partner network enables us to provide continued support for our clients, no matter the complexity of their application needs. Contact us for assistance with your next project. We’re here to help and we’d love to hear from you!

To learn more, please call 972-459-8200 and ask for the Pressure Management Team.