| dc.description.abstract | If one could imagine a single pipeline spanning approximately 11,000 km from Oslo, Norway to Bangkok, Thailand, this would be similar to the total length of the Norwegian oil and gas pipeline network combined [1]. The hydrocarbon resources located in the cold waters of subsea fields offshore Norway, are transported via pipelines to either an onshore processing facility or directly exported to consumers in the UK and European Union area. Long sections of this transportation pipeline network require protection from potential hazards, such as trawling-shipping activities and dropped objects. One common method of pipeline protection is the installation of concrete mattresses on top of the pipeline. Concrete mattresses are also utilized where soil stabilization and foundation support is needed.
Despite a large number of concrete mattress installation projects is performed annually, the current deployment method is relatively inefficient, as each mattress is individually lifted and installed. The present thesis proposes a handling mechanism for the deployment of multiple concrete mattresses in a single lift.
Initially, Subsea 7 proposed a concept for a multi-installation tool. The concept comprised a steel frame that would facilitate six concrete mattresses and embody a handling mechanism with rotating pipes and gears. The mattresses will be lowered to the seabed through the mechanism with the assistance of a ROV torque tool. The key feature of the project is the study of the handling mechanism, and more specifically, to resolve the concept under certain requirements, elaborate on its operational and installation aspects, and assess the structural integrity of the finalized solution.
The initial concept is thoroughly presented and examined. The operational procedure and the functionality of each component is also discussed. The design phase starts with the dimensioning of the rotating parts of the mechanism, which yield the required design values of the gearset.
In the sequel, an arrangement of spur gears is designed according to the limitations that have been set. The strength of the gearset is evaluated with the use of analytical solutions. Additionally, a finite element analysis of the response of the gearset is performed for verification and comparison purposes.
Finally, the current thesis work concludes to a new configuration of the handling mechanism with the use of alternative ROV tooling aids. The design of the new setup is presented and the structural integrity of the new components is assessed. Lastly, some recommendations for future work are given. | nb_NO |
