Another successful inspection performed in Q4 of 2015 was the external inspection of flexible pipes located on a turret drag chain of a FPSO for wire gap disorganisation.
Arranged in a ’bull-nose’ structure inside the upper part of the turret drag chain on the FPSO, the flexible pipes are subjected to external tensile armour wire disorganisation. An external inspection on four 10’ and three 6’ flexible pipe sections stacked in 70 masts of the turret drag chain was performed to identify, monitor and measure the increasing wire gaps of the flexible pipes.
As the aim of the inspection was to detect the signals from the surface to determine the wire gaps of the flexible pipes instead of penetrating into the flexible pipe structure for defect detection, the MEC-FITTM technique had to be verified for its suitability prior the inspection campaign. It was successfully verified for its capability and repeatability in determining the individual wire gaps.
The tight space between the flexible pipes on the drag chain configuration meant that the inspection tool must fit in between the 150mm gaps. As a result, a handy and flat MEC-P7 Pipescanner which was a modification of hand-held MEC-Pipescanner normally used for topside inspection was built and deployed customised. The MEC-P7 Pipescanner was customised with a high resolution encoded drive to enable the precise definition of the wire edges and the distance to the neighbouring wire.
This wire gap monitoring inspection operation was successfully performed to the satisfaction of the client.