As ROVs are given tasks in more and more challenging environments, there has been a call for the industry to develop a classification system. Meg Chesshyre reports.
Saipem’s Innovator ROV. Image from Saipem.
A call for the International Marine Contractors Association (IMCA) to help set up a round table to develop a classification system for work-class remotely operated vehicles (ROVs) was made in a paper at the association’s recent annual seminar in London.
The paper, presented by Saipem subsea remote technology engineer Lorenzo Granelli, was co-authored by subsea remote technology project manager Giovanni Massari. Both authors are involved in the project engineering and production of new ROVs for Sonsub/Saipem.
Granelli says a classification system is needed for ROVs, just as there is for vessels. “If you ask for a crane vessel you have a clear idea of what you are asking for. If you ask for a work-class ROV, no one states what it is,” he says.
Granelli sees IMCA as potentially the missing link between two engineering worlds, the engineering and manufacture of ROVs, and subsea project engineering, undertaken by the main contractors and the major oil companies.
He says ROV manufacturers need input to steer their research and development programs in the right direction, and a clear vision of the technical specification of ROVs. The project engineers also need to know what an ROV can or cannot do so they can plan their operations in the most effective way. It was also suggested that input from Xmas tree manufacturers might be included in the round table.
Granelli says there is also a need to define a way marine contractors can efficiently drive new developments on the basis of real needs, with the identification of standard requirements for current and foreseeable jobs in terms of ROVs, interfaces and tools. It is important to define a way in which new technology can be validated so that only well proven solutions are adopted, and to identify procedures and best practice to test ROVs or technical solutions against requirements, he says. There is also a need to redefine classification for new ROVs with a clear idea of performance.
ROV technology has reached an early maturity phase. While ROV functionalities are well defined, there is still considerable room for improvement, Granelli says. Main ROV manufacturers assert ROV technology is comparable with the automotive market at the beginning of the 1970s, he says. There is also a need to improve ROV operability, to guarantee highly reliable systems with a reduced maintenance cost and optimized availability. For optimal ROV operation, ROV crew capability is also a key factor for the success of an intervention.
As subsea construction programs go deeper and get more complex, in harsher environments, the demands on ROVs will continue to increase. Workclass ROV technology development will be driven by those factors that will directly impact on the capability to win contracts for state of the art subsea projects, Granelli says, in new operating environments such as the Arctic, or in areas of poor visibility and ecologically sensitive environments.
New operative tasks will include permanent inspection, maintenance and repair of subsea fields, or remote intervention by means of subsea resident vehicles, emergency intervention, touchdown point monitoring for deep water S-lay projects. The development of so-called subsea factories will lead to new construction, maintenance and inspection needs, Granelli continues. More automated or independent/semi-independent tasks are also emerging.
There are a number of different classifications and standards in existence covering ROVs, for example, DNV-GL i-5-3, ISO 13628-8, Norsok U-102-2, API 17H, IMCA r004, ABS osv-5, but on the whole they are very general. There are no specific requirements for maximum dimensions for specific operating scenarios and tasks, or for continuous dive time capability for specific operating scenarios and tasks, of particular relevance for operations in the Arctic, where access may be limited, guidelines are needed for validation of new features, tools and technical solutions, Granelli and Massari say. Environmental operability limits are needed in terms of temperature and significant wave height.