A pressure vessel experienced an overpressure event that exceeds the maximum allowable working pressure (MAWP). Externally, there was a movement of piping observed at the supports of up to 2”. Internally, the baffles, attachments, and internal piping had either moved or were completely separated from the shell.
Aside from only the attachment welds being affected, a slight movement was observed and there were no obvious signs of damage to the shell. The client was on the cusp of repairing the damaged vessel and returning it to service. However, the Chief Inspector (CI) wanted an assessment to prove that the vessel was safe for continued service. Assistu was called upon to provide advice as to how to assess the integrity of the vessel. It was suggested to use laser scanning and FEA software to perform a Fitness for Service (FFS) assessment. Although not noticeable to the naked eye, there were large areas in the shell which incurred significant deflections.
Results were provided within 2 weeks. Assistu achieved an efficient turnaround by performing a preliminary assessment to determine pass or fail. The client was able to decide quickly to either replace, repair, or leave as-is to reduce the impact of lost production. Results were presented in a report for documenting the assessment.
After a preliminary assessment was completed, the stresses were determined to be unacceptable. Although options were provided to de-rate or repair the vessel, it was decided the more economical approach would be to replace it. Assistu provided key information for the client to be able to make an informed decision that is cost effective and safe.