The customary way of performing inspections of river crossings more than 3 m deep is to send men underwater, so as they see and feel the pipelines if they are over the riverbed or use a steel rod to assess their depth under the riverbed, where they are buried under it. The main problem of that approach is, diving is a risky venture, linked to several accidents, sometimes fatal. Transpetro has looked for an alternative way to avoid diving. The first experience with diverless technologies was with a Sub Bottom Profiler, back in 2017. At that time, the profiler was considered only as a complement of the diving activity.
In 2020, we made our first experience with the combined use of three pieces of equipment: a Sub Bottom Profiler, a Side Scan Sonar, and an Echo bathymeter. This first experience took place in the Billings Lake, part of the Billings Dam, near São Paulo, SP, Brazil. Using that combined approach, we could acquire information about the depth of the pipelines, for the buried lengths, as well as the extension and height of clear spans for the lengths above the riverbed.
Since the depths under the riverbed should be known and controlled and since clear spans are potentially dangerous (if they are longer than the admissible span), these are invaluable information on the safety conditions of the pipelines. Since 2020, Transpetro have been using these technologies in several more crossings, whereas diving was used in only one case, to assess doubts about clear spans. It can be concluded that circa 90% of diving was eliminated, with the associated risk reduction.