This directory contains a listing of:
Please note: if a company does not meet at least one of these four criteria, it will not be listed in this directory.
- Manufacturers of boilers, pressure vessels, or other pressure-retaining items who
are authorized to register these items with the National Board;
- Manufacturers of pressure relief devices who have had these items capacity-certified by the National Board;
- Repair organizations holding National Board Certificates of Authorization for use
of either the R, VR, or NR stamps; and
- Pressure relief valve testing organizations holding National Board Certificate of Authorization for use of the T/O Certification Mark.
- Be as general as possible if entering a company name. A company may spell its name
differently on their certificate than how they are known to the public. We suggest
typing in only the first letter or two in the company's name, or simply leave the
company name field empty to ensure you receive all possible matches.
- Know the exact city for the company or plant you are trying to locate. Many times
a plant may have a different physical location than the city it is commonly associated
with. If you do not have this information we suggest you leave this field empty.