Remote support underpins major overhaul of first X-DF engines on LNGC

CSSC Marine Service (CMS) overhauled the two 6X62DF engines on LNG carrier SK Audace while at anchor in Sabine Pass, Texas.

Owned and operated by South Korea’s SK Shipping Co, SK Audace was the first-ever X-DF-powered vessel in operation. Since SK Audace’s delivery in 2017, its X-DF engines have reached 18,000 operating hours, more than 99% of which was in gas operation. The LNG carrier operated on diesel less than 1% during manoeuvring.

The CMS Korea team completed the two engines’ full maintenance within nine days, and the ship returned to commercial service after a successful sea trial. The work was completed in short order despite the travel, logistics and health and safety working precautions implemented as a result of the Covid-19 pandemic.

Although work scopes were varied, CMS and WinGD collaborated to execute the job according to the standard manual for that engine type. Original spare parts such as piston rings and gas components were delivered to the vessel’s location by CMS.

During the engine overhauls, the CMS Korea team received real-time support from the WinGD design team. WinGD reported that the CMS Korea team observed that the 6X62DF engine parts were in "incredibly good condition" as compared to similar overhauls of engines that operate on heavy fuel oil (HFO).

Following the overhaul, the trial run of the engines was performed in service power and optimised engine performance was calibrated. To ensure optimal engine operating standards through to the next periodic maintenance, the CMS Korea team conducted maintenance on the pistons, exhaust valves, flow limiting valve and fuel pump component, overhauling and replacing where necessary. Additionally, the overhaul included more complex gas components such as gas admission valves, pre-chamber replacements and gas valve units.

In total, 10 X-DF engines on five vessels will be overhauled by CSSC Marine Service in the coming months. Results of the ongoing condition-based investigation on all five vessels will enable increased time between overhaul or condition-based maintenance decisions, to be agreed between the shipowner and classification society.

CMS president Andrew Stump, said “For customers who operate X-DF engines and have concerns about service accessibility, CMS is able to provide qualified service through our growing network. This is the first X-DF major engine overhaul completed and our team provided such a short turnaround time for a twin-engine installation that truly proves what is possible.” Mr Stump added "The results recorded in the service reports have been investigated together with WinGD product managers in the Swiss headquarters, and we are all extremely happy with the condition and cleanliness of engine components, in particular compared to an engine of the same running hours operating on HFO. The results of investigation by WinGD will enable any design optimisation necessary and extension of the time between overhauls where appropriate. Once we have comparative results from the sister vessels we will be able to confirm the success of the X-DF product as the most reliable and sustainable LNG main engine solution”

SK Audace superintendent said “As the first-ever X-DF engines, I had concerns about the scope of the project. But the CSSC Marine Service team demonstrated their ability with a fast and professional overhaul.”

CMS has three service hubs, in South Korea, Singapore and Hamburg. Additionally, it operates five service stations located in China, South Korea, Singapore, Hamburg and Switzerland. Partner service stations are also located in Brazil, Turkey, Poland, South Africa, Oman, Qatar, Dubai, the US, New Zealand and Greece.