No Drydock Needed

File image courtesy SGS

Published Jan 26, 2018 9:51 PM by Subsea Global Solutions


In November, a fully loaded bulk carrier contacted Subsea Global Solutions (SGS) with a shaft seal issue. They reported that they were losing all stern tube oil into the vessel and were experiencing heavy water ingress through the forward seal system into the engine room. Thanks to a well-thought-out repair, they made it safely to their original destination and discharged their cargo - before heading to drydock, not after. 

After the initial report, the vessel was towed from an anchorage in Russia across the Black Sea to a more favorable location in Eastern Europe. Teams from SGS offices in Vancouver, Miami, Long Beach, Halifax, Houston, and Tampa were dispatched to attend. Once inspections began, it was found that the tail shaft had dropped outside acceptable tolerances due to bearing failure. This bearing failure  was the root cause of the damage.

Together with the responsible class society, the team put together an emergency repair plan for the bulker so it could continue on its way to its deliver cargo, then go to dry dock. If the shaft seal integrity could be reinstated and a successful running test could be conducted to the class society's satisfaction, the vessel would be allowed to sail.

For the seals to be brought back into eccentricity with the shaft, modifications to the seal housing flange were conducted. This consisted of the disassembly of the entire split type seal system inside SGS's proprietary Transhab habitat, a lightweight, inflatable underwater habitat that is fitted around the stern seal, thereby providing a dry environment large enough for two technicians. The housing flange was modified in accordance with specifications developed by SGS’s engineering department in consultation with the seal supplier.  Once machined, the system was assembled with new bonded shaft seals. The aft seal assembly was aligned with the shaft eccentricity within original tolerances. The internal seal assembly and clamp ring was put back into radial and axial alignment and backed up by an additional hold back as an extra precaution.

After working around the clock in extreme weather, the running test was conducted pier side. All testing was completed, and the class society approved for the vessel to make a one-way trip to its next port of call for cargo discharge. The vessel completed its voyage, discharged its cargo and entered the dry dock for permanent repair. 

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.