The majority of the pressure vessels were found fit for service, but there were three issues requiring solutions that arose over the course of the assessment.
Problem: incomplete design data. Solution: as pressure vessels have a finite number of configurations and use standard fittings, the design of the vessel could typically be determined from the inspection report and therefore endorsed on that basis.
Problem: incomplete inspection data. Solution: A hydrogen damage survey was performed on several pieces of equipment and it was found that only vessels of a certain age and construction appeared to be susceptible to hydrogen-induced damage. From this survey, the susceptibility of any vessel could be inferred.
Problem: genuine internal corrosion. Solution: There were many reported instances of localised internal corrosion. These were detected by deviations in wall thickness. Checks were performed on deviations to determine the validity of the result. The system only failed endorsement when these deviations were deemed accurate and large enough to undermine its integrity.
Although the assessment found that some of the vessels could not be endorsed, those that fell under this category were already out of service and scheduled for decommission.
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