Inspection of critical areas in air-cooler tubes.

Haukanes, Frode; Aker Solutions AS; Norway

Haukanes, F.; Aker Solutions; Norway

ID: ECNDT-0152-2018
Session: Oil & Gas 1
Room: H2
Date: 2018-06-11
Time: 13:50 - 14:10

Air cooler units are normally carbon steel tubes with aluminum fins that are cooled by a fan underneath. Inspection of tubes in these units are done by tube inspection techniques such as Near field testing, IRIS, MFL or Acoustic technique. The most common degradation is ID pitting or general ID corrosion wich can be detected by combining these techniques . However there is an area in these tubes that are difficult and challanging to inspect. The area where the aluminum fins ends and the tubes enter the header box. This gap can be 0-70mm depending on fabrication. This area is exposed and we severe degradation can often be seen on the upper row of tubes. Theseupper row tubes can be inspected with radiography, but all tubes further down are impossible to inspect like that. A UT application like IRIS could be applicable, but we we got an additional challange since the client could not allow water or any form of couplant to flow inside these tubes because of the process conditions. So we did several trials and developed a tool with an ultrasonc application. We then inspected these areas in all tubes without leaving any couplant inside the tubes. All data are digitally recorded and stored for future trending and monitoring. Each tube take approximately 7 second to inspect.