The MEC-FIT™ flexible riser inspection technique had been successfully deployed on a 7.5’ unbonded flexible riser located on a jack-up rig in the Norwegian North Sea.
Performed in December 2014, the inspection scope was to scan a section of the flexible riser normally covered by the bend stiffener from below the flexible riser top connector down to approximately 2 metre. External corrosion at the armoured layers of the flexible riser had been suspected as a result of the cracked outer polyethylene sheath due to the extreme operating condition and temperature. The water collected at the connector could potentially ingress between the cracked polyethylene and armoured wires. As a result, the inspection task was to determine the pitting corrosion level at the first and second armoured wire layers of the flexible riser.
The bend stiffener was lowered to allow access to the surface of the flexible riser. However, the accessible area from between the top of the lowered bend stiffener to the connection flange was shorter than 2 metres. As a result of the space constraint and weight limit, the setup of the rigging system at the riser section was not possible and the marinised MEC-MPS200+ scanner with a larger dead zone could not be utilised.
Instead, the smaller hand-held MEC-P19 Pipescanner normally used for the topside inspection of pipelines and vessels was adapted with the MEC-FITTM flexible riser inspection technique and deployed to perform the inspection.
This shows the versatility of Innospection’s equipment which enable the incorporation and adaptation of different inspection techniques to meet the deployment and inspection requirements.
The MEC-P19 Pipescanner was manually deployed from the topside and the scanning of the riser was performed in both the axial and circumferential orientation. Light indications at specific areas were detected and different phase settings were used to determine the type of defects such as wire disorganisation, enlarged wire gaps, external and internal metal loss.
Visual and X-Ray inspections performed in parallel confirmed and verified the findings obtained by the MEC-P19 Pipescanner with the MEC-FITTM technique.