Ultrasound Condition Monitoring Of Existing Imperfections In Static Equipment

Continuous operation of static equipment is not possible without assessing the metal condition, and one method to implement the asset management strategy is ultrasonic (UT) analysis of existing imperfections. A focus is placed on the risk-based inspection (RBI) of a high-pressure amine absorber in service where a zone with permissible short, scattered indications is found before the commissioning. The vessel has been hydrotested and put into operation, and the corresponding risk category has been defined. It has been in service for ten years, with regular thickness measurements and maintenance performed. The subsequent scheduled inspection is set at every five years. Initially, RBI recommendations are followed based on the criticality of the asset and the severity evaluation of the imperfections. For an absorber made from P355NH with a height of roughly 17 m and a diameter more than a meter, shell metal UT zones of a total size of 2.115 m² have been evaluated. No crack-like faults have been detected, and the existing rounded imperfections with a diameter of less than 4 mm are being monitored for eventual growth. Since no change is observed after the strategy-defined five-year period and all the inspection protocols show consistent results, an RBI reevaluation is performed for the definition of the new risk category. As a result, there is a decrease in the calculated risk of the corresponding asset.

Funding: The author acknowledges support from project BG16RFPR002-1.014-0005.