Speedy turnaround for first X-DF major overhaul


The SK Shipping owned and operated <i>SK Audace</i> (Image credit: SK Shipping Co. Ltd)The SK Shipping owned and operated SK Audace (Image credit: SK Shipping Co. Ltd)



The first major overhaul on two WinGD X-DF engines has been completed in nine days. The overhaul was conducted by CSSC Marine Service Co (CMS), the worldwide equipment service subsidiary of China State Shipbuilding Corp (CSSC).

The twin 6X62DF engines overhauled belong to the first X-DF powered vessel in operation, 2017-built 180,000-cbm LNG tanker, SK Audace (Owned and operated by SK Shipping Co. LTD), which was anchored at the Sabine Pass anchorage in Texas.

In the three years since vessel delivery, the X-DF engines installed on SK Audace had reached 18,000 operating hours, >99% of which were gas operation and <1% Diesel operation required for manoeuvring. Therefore, scheduled maintenance was required to ensure continuous uninterrupted operation. 

The CMS Korea team completed the full maintenance on the two engines within nine days, and the ship returned to commercial service after a successful sea trial run. The rapid completion of the work, despite the disruption to working plans caused by Covid-19, reflects the skill and dedication of the CMS team, along with the simplicity of the X-DF engine for maintenance.

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 overhauls, no abnormalities were found. However, the team overcame the challenge of the unknown and being the first ever to perform maintenance on X-DF technology. The CMS Korea team prepared their work guidelines well which included the reservation of correct materials and real-time support from the WinGD design team. The CMS Korea team also observed that the 6X62DF engine parts were in incredibly good condition compared to engines historically overhauled by CMS that operate on heavy fuel oil (HFO).

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

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 TBO (time between overhaul) or CBM (Condition based Maintenance) decisions, to be agreed between the ship owner and classification society. 

Andrew Stump, President CMS says: “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. As the demand for our services grows, CMS will continue its expansion into more locations worldwide.

“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.” 

The 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. Working closely with WinGD really made a difference to how quickly we were able to resume operations. We look forward to working with the team again in the future.”

To-date, CMS has established three service hubs located in South Korea, Singapore and Hamburg. In addition to the service hubs and operates five service stations located in China (Qingdao, Gaungzhou, Chengxi and Shanghai), South Korea, Singapore, Hamburg and Switzerland. Partner service stations are also located in countries including Brazil, Turkey, Poland, South Africa, Oman, Qatar, Dubai, US, New Zealand and Greece.

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