At an oil refinery, non-permissible defects were found in the upper part of the gas adsorber of the circulating gas (commissioned in 1970). From 1999 to 2009, the lamination was known to exist in the main upper end plate (the area of the lamination ~0.4 m2, the depth of the lamination 6.1-12.4 mm). On the same unit, the defect of the planar type (crack) in the weld of the shell to the end plate (length 140 mm, depth 12-14 mm) was also present. This gas adsorber has the following parameters: working pressure 4.2 MPa, operating temperature +45°С, wall thickness 22.0 24.0 mm, the inner diameter 1.156 m and the height 16.45 m.
A preliminary decision was made to install a monitoring system for the upper part of the adsorber. The main task of the monitoring system was to ensure safe operation of the adsorber before its replacement within a year. Prior to installation of the monitoring system during the overhaul in the spring of 2012, its AE testing was carried out. AE sources of class I and II were registered, the locations of which were correlated with the place of previously detected defects on the vessel head of the adsorber. This allowed us to assume the possibility of further expansion of the lamination zone during the life extension period of the adsorber.
Based on the results of the AE testing, the previously approved decision on the installation of the monitoring system for the vessel head of the gas adsorber was confirmed. The system successfully done the task. Adsorber was operated before its replacement.