An 80 metre Diameter Crude Oil Storage (COS) Tank was required to have an Online robotic Tank Floor Inspection conducted to extend the endorsement as the tank was due major overhaul but could not be removed from service due to operational ullage requirement.
COS Tank 260 Feet – SONAR Online
OUTCOME
Just over 3 years later the tank was removed from service and internally inspected. The results of
the two inspections were as follows:
The In-Service Robotic Inspection of the 80m Crude Oil Tank with sludge up to 1m provided data that when projected forward to the time of the Out of Service UT was deemed to be incredibly accurate and comparable.
A difference of 0.33 mm could be considered to be within the uncertainty of a
manual UT reading and the percentage difference between the two methodologies was less than 5% using the HOIS Statistical Analysis of Corrosion Data.
