Subsea Pipelines Inspection with Next Generation MEC & PECT Techniques
Maintaining the integrity of coated and uncoated subsea pipelines is a challenge due to accessibility issues and difficult inspection conditions such as the water depth, visibility and temperature. As large amount of the subsea pipelines are non-piggable, the typical internal inspection involving the installation of a subsea launcher and receiver is also costly.
To overcome this inspection challenge, Innospection has developed an external subsea pipeline inspection package based on the MEC (Magnetic Eddy Current) technique for the external inspection and condition assessment of the non-piggable subsea pipelines, subsea flowlines and manifold pipes.
The next generation MEC technique is used by Innospection as a key tool for integrity assessment support. With high sensitivity in detecting internal and external defects including small and shallow pitting, cracks and thinning, the MEC technique is capable of inspecting through higher wall and coating thickness as well as direct sizing of defects during scanning without the need for Ultrasonic verification.
To deploy the MEC technique, the fleet of sophisticated MEC-Combi PipeCrawlers has been designed and built to offer a cost effective inspection solution by targeting inspection, deployment and subsea accessibility challenges. In addition, the MEC-Combi PipeCrawlers are capable of providing comprehensive inspection data within a single deployment as supporting inspection technique such as high resolution Ultrasonic mapping, Pulsed Eddy Current, laser triangulation and camera system can easily be incorporated.
Deployable by divers or work-class / inspection-class ROVs from support vessels, the MEC-Combi PipeCrawlers are capable of self-crawling along the inspection surface to perform the scanning in axial and/or circumferential orientation while remaining in stable contact with the inspection surface despite the turbulences and waves due to its integral buoyancy and magnetic system
Figure 1 – MEC-Combi PipeCrawlers inspecting the subsea pipelines
For the inspection of heavy weight concrete-coated subsea pipelines, the next generation PECT (Pulsed Eddy Current Testing) technique is deployed. The PECT technique offers enhanced wall loss detection capability including the ability to inspect through 250mm of coating to detect the corrosion and defects beneath. It’s highly repeatable results make PECT well suited for the wall thickness monitoring of coated subsea pipelines.
The PECT inspection of coated subsea pipelines with OD from 12” to 20” is currently performed with the diver deployed Subsea PECT Scanners capable of axial and circumferential scanning. A semi-automatic scanning ring that is remotely controlled by the operator improves the inspection performance, particularly the timing and reproducibility.
Figure 2 – The semi-automatic scanning ring to improve the PECT inspection of coated assets
To help the Operators solve their niche inspection challenges of their subsea assets, a large in-house R&D team supports the company in the development of optimum inspection solutions and equipment.