Power on the Intrepid: The 2955 gt vessel is powered by four Wärtsilä 6L26A diesel engines and propelled by eight Wärtsilä type FS500/-226/500, fully azimuthing, fixed pitch, variable speed, retractable thrusters, controlled by a dynamic positioning system. |
Time was of the essence, when the Houston-based Helix Energy Solutions Group approached Wärtsilä to carry out an overhaul of eight thrusters installed on their reeled pipe-lay vessel Intrepid during a recent dry-docking. Time to use – 28 days.
The customer stressed that time and money was a concern and that yard support would be very limited. We, therefore, needed to be completely self reliant in meeting the customer’s requirement that all eight thrusters were to be dismounted, completely overhauled and replaced in just 28 days.
Multinational team established
From the outset Wärtsilä assembled a team of propulsion specialists from its global service network that included specialists from North America, the Netherlands and Canada. The multinational team gathered at the Wärtsilä repair facility in Houston, Texas, where a plan of action was conceived to meet the challenge.
In short, the retractable thrusters needed to be removed from the pipe-lay vessel as quickly and efficiently as possible, after which the 24,000h overhaul work could commence.
Overhaul and thorough testing
Customer Statement:
“This was an outstanding job performed in an extremely short time frame by very professional and experienced technicians. It required a tremendous amount of coordination and planning both on and off site and the end result speaks for itself; we have had no problems with the thrusters of any type since we put the vessel back in service.”
David Murphy
Marine Manager of Helix Energy Solutions Group.
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The removed thrusters were taken to the Wärtsilä workshop in Houston. Once there, overhaul of the retractable thrusters consisted of a complete disassembly, inspection, and then reassembly of the upper gearboxes, steering pipes and lower gearboxes. After that the equipment was carefully placed back aboard the ship. The American Bureau of Shipping (ABS) was involved during this entire process, because their approval of the work was required; from the rebuild in the shop to the final installation and testing.
Each gearbox, 14 in total, was marked and carefully disassembled to ensure that any existing problems were noted. All critical components, such as gears and shafts, were then subjected to non-destructive testing. This was done to ensure that any potential cracks and damage not visible to the naked eye could be found before reassembly of the units. This kind of testing was necessary considering the critical nature of the equipment and the environment in which the vessel operates.
Working around the clock
One of the major critical success factors for this project was the extremely close cooperation and coordination between the blast paint activity and Wärtsilä’s work. “At night, the dry dock was quiet, which was a factor we could utilize to be more productive. All eight thrusters, with their propellers, rope guards and nozzles, were remounted. Then we installed the drive shafts and upper gear boxes and reinstalled all the associated equipment, such as pumps, steering motors and motor brakes. The thrusters were then filled with oil and calibrated to ensure that they would retract as designed, once the vessel was back in the water,” said Karl Russell, Project Manager Wärtsilä North America. Working around the clock, it was possible to meet the challenge and keep to the time schedule.
Once the vessel was afloat again the thrusters were put through their paces and tested to ensure the equipment would perform as required. Every unit was tested at maximum speed and to maximum power, to the full satisfaction of the vessel’s captain and chief engineer – and still within 28 days.
Intrepid is propelled by eight Wärtsilä type FS500/-226/500, fully azimuthing, fixed pitch, variable speed, retractable thrusters, controlled by a dynamic positioning system. |
Once removed from the vessel, the thrusters were taken to the Wärtsilä workshop in Houston. |
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