Gas turbine propulsion gets LR approval

Lloyd’s Register Asia has recently completed the first full safety case of a gas turbine propulsion system for LNG carriers of 250,000 cubic metres and above for Rolls-Royce?s MT30 system. Carried out in conjunction with Daewoo Shipbuilding & Marine Engineering (DSME) and Rolls-Royce, this work was designed to fulfill the requirement of the oil majors involved in the QatarGas and RasGas projects that shipowners, yards and class ensure that proposed ship design concepts are as sound as practicable.

Gas turbine propulsion systems have been widely used on naval and cruise ships but are relatively new to LNG vessels, which have traditionally been powered by steam turbine engines. This safety case is the first of its kind to be completed within the major Korean shipyards and puts DSME and Rolls Royce in a leading position to offer gas turbine propulsion as a viable alternative for the large LNG carriers of the future.

Work began on the project late last year with detailed engineering drawing development by DSME and Rolls Royce. LR Asia provided a risk assessment methodology for evaluation of the gas turbine propulsion system and facilitated its execution with an early hazard identification (HAZID) study in December 2004. This was followed by a full safety case, combining a further HAZID study and a hazard and operability (HAZOP) study of the developed arrangements in April.

Bearing in mind that the gas turbine would normally be fuelled by boil-off gas from the cargo tanks themselves, the safety case paid particular attention to the ship?s high-pressure gas supply system. The HAZOP study covered failure modes and the maintenance of propulsion and electrical power in the event of a gas turbine failure.

“We are delighted that the pre-qualification work has been successful,” says D Y Lee, Executive Director of DSME. “LR Asia?s safety-case approach has once again enabled us to address the relevant design and installation issues and build confidence that risks to the system, the equipment, to owners, operators and the environment have been minimised.”

“We believe that the power and efficiency of the MT30 gas turbine propulsion system is ideally suited to larger LNG carriers travelling on longer journeys,” says Richard Smallwood, Rolls-Royce Business Director. “The process has gone extremely smoothly thanks to Lloyd?s Register Asia?s input.”

Thanos Koliopulos, Safety Case Project Leader for LR, says: “The Lloyd?s Register Group has successfully applied the safety case method to a number of LNG-related projects and we are pleased to have been able to assist Rolls-Royce and DSME with the MT30 gas turbine propulsion system.