There are many industry specific certifications in vessel manufacturing that regulate the construction of a vessel. However, for many types of pressure vessels, ASME certification is required and may be in addition to other industry requirements due to the vessel's geometry and pressure designation. Any tank that meets the requirements of ASME Code Section VIII can be certified. This certification is frequently referred to as "stamped" because the code symbol is most commonly applied using a stamp process. Here are the main differences between ASME U and ASME UM symbols and certification. ASME Certification with U Symbol Any vessel meeting the requirement of ASME Section VIII can be marked with the U Symbol. Most local and state laws require vessel designs 15 PSI and higher to be ASME Code Certified. Qualified manufacturers receive a triennial joint review (audit) by their authorized inspection agency, and the National Board of Boiler and Pressure Vessel inspectors. U vessels require an Authorized Inspector (3rd party ASME inspector) to review with approved calculations. U vessels require an ASME pressure test with the Authorized Inspector residing over the test. ASME UM Symbol UM vessels are smaller in volume (less than 5 cubic feet) UM qualified manufacturers receive an annual ASME review by their authorized inspection agency and are also subject to the same triennial joint review (audit) as mentioned above. UM vessels have size specifications, including: 5 cubic feet of volume or small with pressures not exceeding 250 PSI 3 cubic feet of volume or smaller with pressures not exceeding 350 PSI 1.5 cubic feet of volume or smaller with pressures not exceeding 600 PSI UM Vessels are inspected and tested by a manufacturer's own certified individuals. Note that there may be exceptions to the ASME Certification requirements, depending on your state and local municipality. Apache manufactures tanks and vessels for compliance and regulated industries, including pharmaceutical, food and beverage, petrochemical, biofuels, chemical and life science. We hold these certifications: ASME U Certificate, ASME UM Certificate, National Board of Boiler & Pressure Inspectors R Certificate, and National Board of Boiler & Pressure Vessel Authorization to Register Certificate. Questions? Please call and ask for a Sales / ASME Specialist at 920-356-9900.