The Challenge

Design of any subsea component or mechanism requires expert knowledge and a real focus on risk analysis to ensure that no failures or faults occur within planned maintenance intervals.  Unscheduled interventions are extremely costly, not only in terms of lost generation revenue, but also incur very high offshore vessel, diver and other specialised personnel costs.  During device development projects, failures can damage reputations and in extreme cases can result in withdrawal of investments.

The project design team were experienced working in an offshore and subsea environment, and combined with PEC’s deep-water experience, gained from working on devices and structures associated with the UK fleet of submarines, were able to produce mechanical assembly drawings which would prove to be reliable in service.  Clearly, the failure of a pull-down winch in either of the pulldown or release modes could prove very costly.  Similarly, if the turbine rotation mechanism failed either the turbine could not be put into generation orientation, or could not be prevented from rotation for maintenance activities.  Thus, both mechanisms had to be completely reliable.

The project also required PEC to manufacture the nose cone units which were to be hinged and provide buoyancy for the PLAT-O device.

Our Solution

Once designs for the pull-down winch assembly and turbine rotation mechanism were finalised, it was a simple matter for PEC’s machining group to produce the necessary components.  Materials were carefully selected, taking into account the duty and planned likely lifespan of the PLAT-O 1 tidal generator, and coating systems specified.

Once installed, each assembly was trialled, and in the case of the pull-down mechanism, also load tested in SME’s assembly shop.

PEC’s experience manufacturing buoys and other marine based structures made the production of the potentially complex nose cone a straightforward one.  Materials were selected based on duty, and taking into account the expected lifespan required, in order to minimise costs.  PEC’s ability to machine large non-metallic items ensured that the manufacture was entirely routine.

The Outcome

PLAT-O 1 was successfully manufactured and successfully tested by SME in the waters off the coast of the Isle of Wight before being taken to the EMEC test facility for further trials.

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