Used vessels present unique challenges as we are tasked with proving that the vessel condition is still sufficient to pass the code requirements for the original pressure and temperature ratings.
The first determination is whether the vessel requires Ultrasonic Testing (UT) to determine the level of corrosion. This is not typically required for stainless steel vessels but the final decision would be made by an Authorized Inspector (AI). This Authorized Inspector must be from one of the Canadian provincial jurisdictions or be registered with the National Board. If the vessel is not able to be inspected the UT testing may be done as a precaution. If we run ASME calculations based on the original drawing and then the AI decides it needs to have UT at time of inspection, then the calculations will have to be updated based on the test results.
The documentation required for used vessel registration is as follows:
- The original U1-A form that was completed and signed by the National Board (NB) inspector at the time of fabrication. This form is often available from the national board if you have the original NB number from the nameplate.
- Ideally the original drawing of the vessel if available. If not available, a drawing will need to be created. This will include using the U1 for reference and additional inspection. For example, radiography and physical measuring and inspection to verify the weld sizes, nozzle thickness and elevations/orientations etc.
- If the original calculations are available, they can be reviewed and used as reference for the CRN registration.
- If the original calculations are not available, new calculations done to the original code of design can be run. This would also reflect the minimum wall thickness from an ultrasonic test report if applicable due to corrosion.
- If the nameplate is missing from the vessel then it is very difficult to register even with the U1 and the original drawing. Without the nameplate it must be proven that the drawing and the U1 match the vessel. This involves much more testing (i.e., Radiography, PMI (Positive Material Identification), Magnetic Particle Inspection etc.). Often the cost and time to prove a design without a nameplate negate the value of registration except on very valuable designs.
In Canada vessel registrations require an ASME U stamp as well as NB registration for acceptance. These requirements are the same for used vessel registrations.
