A client has a relatively low redundancy structure with many fatigue-sensitive Access Window and Closure Welds that require monitoring. The platform structure is made up of Closure Welds and Access Window Welds across all four faces of the platform jacket, and there is a yearly requirement for weld inspection on the platform.
Targeted Inspection of Jacket Structural Closure Welds and Access Window Welds
Process
Sonomatic already had the MAG Rover in service, this was ideal for ROV deployed inspection of Closure Welds. However, the awkward geometries of the AWW’s took more consideration. A bespoke tool was designed and developed by Sonomatic with 5 axis of control that can deploy TOFD, 0° and Angle Shear Wave Pulse Echo in one deployment from the platform from a Comanche ROV. The tool has the capability to inspect the apex of each window weld and 250 mm either side of this region.
The inspection process first requires 0° inspection of weld area to map out the geometry. Using sophisticated software, the information collected is then utilised to plot out the weld profile to support the TOFD and Pulse Echo Inspections ensuring the probe assemblies are driven tangentially to the weld centreline around the weld apex.
Outcome
Without this bespoke inspection technology being utilised, these welds were un-inspectable by ROV and the client would not be able to fulfil their integrity requirements. The inspection performance (accuracy & POD) delivered was critical in allowing the client to continue to safely operate the platform. This, together with the ROV deployment from the platform and no requirement for a DSV, enabled the client to reduce the risk to life, time and costs to complete the inspection.
