Inspectioneering Journal

Undocumented Pressure Vessels and Suitability for Service

By Daniel T. Schardine, Senior Engineer at Applied Technical Services. This article appears in the January/February 2023 issue of Inspectioneering Journal.


It is not uncommon for owner/users to encounter undocumented pressure vessels when performing equipment inventories. Undocumented vessels are also commonly bought and sold on the used market. The significance, potential risk, and potential value of this subset of equipment are often poorly understood. What is an undocumented pressure vessel? Why do we care? What do we do about them?

What is an Undocumented Pressure Vessel?

Knowing a bit of history regarding ASME and the National Board is helpful in understanding what this all means.

In 1914, as a result of multiple fatal boiler explosions, the American Society of Mechanical Engineers (ASME) published the first edition of the ASME Boiler and Pressure Vessel Code (ASME BPVC / ASME Code). With this came stamping requirements to demonstrate that the equipment was designed and fabricated in accordance with ASME requirements. The ASME stamp certifies that the vessel was built according to an ASME code by an organization that has demonstrated a quality system sufficient to design and fabricate vessels meeting the minimum requirements of the Code. To obtain and retain an ASME stamp, the organization must pass initial and periodic audits to demonstrate that a quality system is in place to ensure that material control, welding and fabrication conformance and quality, proper documentation, etc., meet the minimum requirements of the ASME Code.

Additionally, during the same time frame, many states and large cities implemented independent boiler laws that had differing requirements for QC inspection and stamping. As a result, interstate boiler sales were infeasible. The National Board of Boiler and Pressure Vessel Inspectors (NBBI / the National Board) was formed in 1919 to uniformly administer and enforce the rules of the ASME BPVC. The National Board qualifies all inspectors in a common set of requirements and issues National Board commissions to successful candidates. The National Board also authorizes manufacturers to stamp a National Board number on boilers and pressure vessels inspected by a National Board Commissioned Inspector. By 1921, the National Board had developed a system of registering and recording ASME boilers. The system was developed to ensure “that no state need fear of a counterfeit Code boiler, if it bears the National Board stamp.” This encouraged boiler sales between multiple states and provided the only central repository for manufacturer’s data reports.

For the purposes of this article, an undocumented pressure vessel is a vessel that:

  • Falls under the scope of the ASME BPVC, generally meaning that it operates at greater than 15 psig internal or external pressure and is greater than 6” inner diameter. Also, state regulations often provide further pressure and volume combination exemptions as well as various other exemptions,
  • does not bear a code stamp/nameplate either because it never existed or the nameplate/stamping has been removed or rendered illegible, and
  • is not National Board registered. It is important to note that the lack of National Board registration does not necessarily make a vessel undocumented. However, many jurisdictions require National Board registration by law.

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Comments and Discussion

Posted by Duncan Humphrey on March 14, 2023
Nice overview, thank you for sharing. We complete... Log in or register to read the rest of this comment.

Posted by Medjahdi Djelloul on March 14, 2023
Dans des cas pareils . Qu'elle est la procédure... Log in or register to read the rest of this comment.

Posted by Mostafa Amirjani on March 17, 2023
Many thanks Daniel. A very familiar topic in... Log in or register to read the rest of this comment.

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