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Spring 2019 29 The software is next used to identify the fl oor, shell and roof, as well as interior deadwood such as piping and structural members. Built-in functions analyse verticality, out-of-roundness and settlement or subsidence around the tank's edges and fl oor. The stations desired for verticality analysis can be selected and RealWorks will produce the two-station plots equivalent to those created by the manual process. The plots and reports are readily incorporated into the fi nal report that the inspection company provides to its clients. In addition to the results of the scanning, these reports contain information on fl oor thickness, pitting or corrosion, welds, nozzles and other issues noted by the inspection team. The automated software can save about half a day in processing compared to the traditional method. Because scanning captures the entire tank, it can reveal issues that would not show up in a conventional inspection. For example, the software can compare the tank shell to a cylinder to reveal any deformation. It can also fi t a plane to the base of the shell to compare the measured fl oor with a fl at surface. Screenshots of any problem areas are included in the reports. The fi nished point cloud provides a comprehensive depiction of the tank. As a result, it can be used for other applications. Tank analysis can develop information on capacity and fi ll levels. Scanning is also used on the exterior of in-service tanks to produce reports on roundness and verticality. The scanners can also capture surrounding conditions, including berms for secondary containments. The software can identify low areas or spill points in the containment berms and then compute the capacity of the containment. The analysis can also account for any expected rainfall and adjust the containment capacity accordingly. One of the most valuable aspects of scanning is the ability to conduct a virtual revisit at any time. When a client requests additional information or questions a report, technicians can quickly access actual measurements and fi eld data to assess the issue. This is especially valuable in assessing tanks that have been returned to service. The rapid time frame and low costs of scanning create new applications as well. For example, scanning new tanks creates precise baseline data on tank dimensions and capacity. The information can be compared with subsequent scans to assess the tank health and performance. Clients can be supplied with free viewer software to enable them to view their tanks from any angle and make measurements within the point cloud. Conclusion While laser scanning helps meet goals of speed, safety and accuracy, it also enables reports to come out faster and include much more information than the older reports. With this technology, inspectors can offer clients more for their money. Figure 3. Scanner data of tank interior showing floor and interior piping. White dots indicate individual measurements on the floor. Figure 4. A tank model with stations for API 653 report. Stations can be created in software during office processing. Figure 5. An inspection uses colour coding (heat maps) to reveal bulges or deformation in a tank shell. The dimensions of the region may be measured directly from the scanning data.

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