Traditional pipe profilers can be error-prone and lead to incorrect interpretation of pipe and tunnel geometry. One of the important elements for understanding the integrity of a pipe or tube is the ovality of that cylinder. Ovality can indicate the presence of undesirable stresses induced into members and reduces the nominal clearance diameter for subsea construction operations. By accurately knowing the dimensions of structures such as pipes, tubes, and caissons, risks can be understood and reduced where needed to ensure ongoing safe operation of the infrastructure.
When a single profile of a pipe is captured, often this is assumed to be the profile of the tube at that location. However, this is only the case if the scanning device is perfectly aligned with the tunnel. If the angle of a traditional single profile scanner is not aligned with the axis of the pipe, ovality will be observed where there is none.
In this illustration, a generic profiling sensor is shown, highlighting how a perfectly aligned sensor will provide accurate shape and measurements where a profiler that has any misalignment will provide an inaccurate assessment of the tunnel geometry.
Given the challenges with aligning any sensor perfectly and the impact that small misalignments can have on the final result, in cases where accuracy is important, single profile pipe scanners should not be used. Since the 2G Robotics underwater laser scanners capture complete swaths of data, the need to have the sensor aligned does not exist, as the centerline of the pipe can be determined from the scan data and a highly accurate cross sectional profile that is orthogonal to the centerline determined.
Because a complete swath of data is captured, the profile location can be selected to be perfectly orthogonal to the centerline of the pipe such that it is perfectly accurate regardless of the alignment of the scanner to the pipe.
Capturing complete swaths have additional benefits that improve the speed and accuracy of any pipe inspection survey. By capturing the complete swath, scanner location setups don’t need to be as precise to capture a specific feature of interest thus reducing total time of operations. Lastly, capturing swaths can also provide accurate full 3D shapes of features rather than just single profiles.