FPSO - Inspect

FPSO vessels are increasingly being used for production and storage of oil from offshore fields. A typical FPSO vessel contains 20km of internal safety critical welds which require detailed offshore inspection on a 5 year cycle. These welds are prone to fatigue cracking due to increases in loading as the majority of FPSO’s were originally ocean going vessels which have been converted and are now carrying heavy oil which exceeds their original design loads.

Current inspection methods for the welds of these vessels have their drawbacks as they require the FPSO’s to be dry docked, emptied and cleaned which is a disruption to production. The inspections are also manual and visual putting surveyors at risk due to exposure to hazardous conditions e.g. toxic gases. 

The aim of the FPSO-INSPECT project was to develop a prototype of a system to inspect the welds inside the FPSO vessels with a full automated robot (below). This will avoid exposing operators and surveyors to hazardous conditions.

The vessel will be emptied and filled with water allowing the robot to swim to its inspection target. The scanner system will then conduct the inspection.  Phased array and ACFM will be used to inspect the cracking defects around the fillet weld and Pulsed Eddy Currents used for corrosion detection on the tank floor where there is often a lot of sludge left.

The positioning robot will know its location within the tank at all times. The tank structure is known, so it is still able to work in a very poor visibility environment.

KCC’s involvement in this project was in the integration of the software for operation and inspection.  Efforts were made to minimise the number of control PCs and software so that the system became applicable to field trials and commercial application.

We also worked on visualisation of defect indication so that the user can easily identify the suspicious location (below)

KCC successfully designed, developed, tested and deployed the man-machine-interfaces and provide on-going software development skills within this area of NDT and defect detection and visualisation.