| dc.description.abstract | The sub-sea industry mainly uses hydraulics with mineral oil as the pressure medium for
operating tools, manipulators, and drive for Remotely Controlled Vehicles (ROVs). Using
mineral oil as the pressure medium comes with several advantages, however, hydraulic systems
are linked to leakage, a threat to the environment. Leaks of mineral oil can also lead to delays
of production, as operations has to halt until the leak has been rectified. It has therefore
been necessary to explore options that mitigates the issue of mineral oil leaks, where one
alternative is electric power. With electric drive comes challenges making it not suitable for
every application, especially when considering the rough handling of tools by the ROV, and
water intrusion in deep sea environment. Development- and recurring cost for electrics is also
substantially higher compared to hydraulics.
To mitigate issues related to mineral oil hydraulics and electrics, Oceaneering AS has started
exploring the possibility of hydraulics using seawater as the pressure medium. This thesis
therefore explores possible concepts of three key components in a seawater hydraulic system;
cylinder, motor, and linear actuator. By using the V-model, Concept of Operations has
been developed for seawater hydraulics as a whole, and Needs and Requirements matrices
has been developed for each component. Existing solutions and literature has been reviewed
to asses possible feasibility of seawater hydraulics. Furthermore, proposed motor, cylinder,
and actuator concepts has been developed into detailed 3-dimensional models with suggested
material selection.
In addition, Finite Element Analysis has been performed on three key components from the
concepts to verify design choices and unveil needed alternations. | |