Inspection of oil and gas infrastructure can be dangerous. In order to maintain the reliability of pipes, tanks, pressures vessels, and other structures, inspection personnel must often work in hazardous locations. These locations include confined spaces, areas that can only be inspected via rope access, heights that require scaffolding to reach, and areas where the presence of volatile organic compounds and other toxins (e.g. H2S) may be present. Meeting the goal of zero incidents and zero injuries requires that operators and service companies implement stringent safety programs designed to ensure that everyone goes home at the end of the day.
Because of the need to limit exposure to hazardous conditions, inspections are generally infrequent. However, frequency of inspection leads to early detection of problems. Early detection of problems is one of the best ways to reduce the economic impact of infrastructure damage. Consequently, there is tension between the need to strive for zero incidents and zero injuries and the need to maintain infrastructure.
Figure 1: Petro-chemical plant
Robotic inspection improves the safety associated with a plant turn-around and enables more frequent inspection. The MR Equus robot, developed by Seikowave with support from Chevron, PRCI, and Asahi Khosan, was designed to meet the needs of NDT teams involved in plant and pipeline inspection. The robot magnetically clamps to steel infrastructure and can move in any direction over the surface of a pipe, tank, or pressure vessel to perform an inspection.
The motion tracking system ensures that all data collected is in a common coordinate system. The data can be associated with reference points inside a plant or on a pipeline (e.g. a weld location) to ensure that the technicians and engineers can locate damage and take corrective action if needed. Although each individual scan is approximately the size of a sheet of paper, the motion tracking of the robot ensures that all of the 3D data is automatically aligned without the need for markers. This greatly facilities inspection in areas where it may be difficult or hazardous to place markers.
An added benefit of robotic inspection is the volume and accuracy of the data that can be collected. The 3DSL NDT software suite, from Seikowave, enables Level 1 and Level 2 assessment of the impact of the damage. The 3D model below was collected robotically and automatically analyzed to determine the remaining strength using Level 1 and Level 2 methods..The 3DSL NDT software suite can also export the 3D data in a standard format that can be used to perform a Level 3 (finite element analysis) assessment of the impact of the damage.The image below shows the Von Mises stress on the corroded pipe as the internal load is increased.
Figure 3: 3D data of a corroded segment of infrastructure
Figure 4: Von Mises stress calculate using FEA
Provided that the correct material parameters are known (e.g. yield strength, tensile strength), finite element analysis can be used to calculate the burst pressure. This is particularly useful on elbows, T's, and other infrastructure where standard ASME and API approaches may not produce accurate results.
The new MR Equus solution from Seikowave, presented at the 2017 API Inspection Summit, highlights how robots can be used to improve safety and inspection results. During 2017, we will be adding ultrasound measurements to the NDT tools on the MR Equus. Seikowave is deploying these new robots globally to help meet the goal of zero incidents and zero injuries. To find out how we can help you, give us a call.