The Code assigns responsibilities to three different entities when it comes to pressure vessels. First is the fabricator, who has the main responsibility to ensure that all aspects of the vessel design and fabrication meet the rules of the code, based on the given design conditions. That means that even if a new vessel is identical to an existing code-stamped unit, the fabricator is still required to perform calculations and verify that the design meets the current edition of the code. Secondly, the owner or end user of the vessel also has certain requirements assigned by the code. They have the responsibility to give the correct design conditions to the fabricator. In addition to the required temperature and pressure, design conditions also include any additional loadings that might be on the vessel, any upset conditions that need to be considered, or any special service conditions such as lethal contents. Owners are also responsible for the installation of pressure relief devices, and to make sure that the vessel never exceeds the stamped MAWP in service. Lastly, the Authorized Inspector has the responsibility to inspect the vessel during fabrication and testing, verify the calculations performed by the manufacturer, and sign the U-1 data report to certify the vessel. With all parties doing their part, pressure vessels are built and operated safely through decades of service.
