Pipeline networks cover extensively modern societies' national territories and can be located in areas difficult to access. This makes their maintenance logistically challenging and potentially dangerous for field personnel. River crossings, where pipelines are buried under the bed of a water stream, fall under such a definition. Recurrent safety monitoring operations entail the deployment of divers with their suit of operational risks and constraints. In addition, most of the tools available are inefficient due to the presence of water. In particular, traditional Ground Penetrating Radars (GPR), are not applicable. Other radio-frequency equipment will provide low-density datasets which rely significantly on human interpretation, introducing measurement biases impacting accuracy and reliability.
Skipper NDT has enhanced its proprietary autonomous technology to serve clients looking to position and secure their pipeline networks under river crossings. Magnetic mapping using a UAS vector allows 1- a quick data acquisition, with less than 30 minutes of flight time per 100-meters of river inspection, and 2- an automated survey without putting field personnel at a safety risk. Gathered datasets present a high spatial density, up to 20 points per meter (6 points per foot), which enables the creation of high-precision digital twins of the buried structure.
In addition, Skipper NDT deliverables are ESRI® compatible and can integrate third-party GIS datasets such as bathymetric or photogrammetric measurements. Thus, a 3D model of the river crossing features using QGIS software was made possible, to further enhance pipeline integrity departments' decision-making capabilities. The performances of the Skipper NDT technology were tested under field conditions with the collaboration of the French Gas operator GRTgaz. This paper is based on 3 case studies from 160 to 220-meter river crossings with a maximum of a 12-meter below water surface. The data shows strong correlation with existing information while enhancing its quality and reliability.