Remotely Operated Vehicles (ROVs) have been in use for many years at sea, often sent down to perform maintenance tasks by remote control, or for filming shipwrecks. Filming of the opening shots of the movie Titanic is a good example of such work. The manufacturer of the ROV used at that time was Houston-based Oceaneering, a leading supplier of ROV services to the offshore industry. DNV selected Oceaneering to help develop a new offshore ROV to be used for scanning hulls and other parts of offshore structures.
Jay Collins - bringing Oceaneering's experience to work with DNV on enhanced inspection capability.
The ROV can scan a hull at the speed of one square metre per second at an accuracy of less than one millimetre on hull thickness.
First of a family
It is a grey, rainy morning in Stavanger on Norways west coast. Here for the first time wee see the Oceaneering Millennium ROV, which, together with the Magnum version, is used in the North Sea. These ROVs, painted in bright yellow, are equipped with two arms with mechanical claws and lowered from supply vessels to perform underwater maintenance. They are operated by cable and an integrated video system.
The new DNV ROV is small, versatile and operates in six degrees of freedom. Oceaneerings project manager Alf-Kristian Aadland explains This new design has six thrusters. We can compare its manoeuvrability with that of a jet fighter. It can roll and loop and move in all directions. In ROV terms, this is new, and it has been an interesting challenge to develop to the requirements of DNV.
President of Oceaneering International, T. Jay Collins, says: We are pleased to be working with DNV to develop inspection technologies and to incorporate them into a new series of capabilities for our offshore customers. Oceaneering and DNV bring world class experience to this combined effort to enhance the inspection, maintenance, and repair of floating systems. This hull-inspection ROV is the first of what we hope will be a family of new technologies to reduce costs, provide fast, accurate information, and add value to our customers projects.
Ease of scanning
Jostein Jacobsen describes the ROVs advantages: Using RTM technology means that our customers FPSOs or other offshore structures can remain operational all the time. Scanning the vessels with our ROV can be done while production goes on as normal. FPSOs are designed to remain on location for many years, and discontinuing production for one to go to a yard for maintenance is costly. Our ROV can be taken to any location at short notice. In fact, the entire system fits easily into a helicopter, including the DNV and Oceaneering operators. The new ROV, due to its manoeuvrability, can also move into the turret area of an FPSO and perform scanning as well as video recording of the condition of the structure and production lines.
The ROV can scan at a speed of 1m2/sec using several sensors and advanced data processing. Combined with a high-accuracy navigational system, the data can be dumped directly into a 3-dimensional digital model, such as DNVs Nauticus system. The ROV itself weighs some 60 kilos, the entire system 150 kilos.