Mini ROVs for UWILD and Tank Surveys of Offshore Installations

For offshore drilling and production facilities, the Under-Water Inspection in Lieu of Dry-dock (UWILD) and other hull inspections can be an expensive, time consuming and disruptive part of vessel maintenance. UWILDs, traditionally performed by divers, raise safety concerns, operational issues, and other restrictions. Some offshore facilities employ a work-class ROV on board which is typically too large and unwieldy to move in close to the hull and perform the detailed inspections required by regulatory and integrity management personnel. Some work-class ROVs cannot operate in the upper water column due to cooling concerns. Divers can work close to the hull, but cannot be in the water with active thrusters, and can only work for a limited duration. Both solutions (divers and a work-class ROV) require a significant support team and a substantial amount of associated equipment. Hull tank inspection presents its own set of hazards, including confined space entry and personnel fatigue. Many of the constraints are either eliminated or significantly mitigated by use of the mini-ROV. Benefits of mini-ROV inspections stem from the ability to access normally unreachable areas and to inspect tirelessly and indefinitely without risk to human life. Everything necessary for a mini-ROV can be transported in a single helicopter and operated by two ROV pilots. Mini-ROV inspections allow the installation to stay in operation during the inspection. This article will discuss and compare current options for UWILD and tank surveys of offshore installations and describe in detail the benefits of using mini-ROV technology coupled with experienced structural engineering understanding for the work. This article will also present case studies from Proceanic's extensive track-record, where the use of mini-ROV technology greatly benefited the industry beyond the traditional methods of survey. Challenges and solutions will be discussed, and proven methods will be outlined which draw upon 2+ years of ROV field work.