Shaft failures cause significant setbacks
Problems with the shafting system are among the most critical issues a shipping company can face. Wear, fatigue, and corrosion can weaken the tail shaft of a vessel, eventually causing cracking and fractures. In serious cases, the ship’s propeller can be lost, leading to significant delays and enormous costs.
To reduce the risk of such incidents, shipping companies must dock their vessels at five-year intervals for inspection. However, before the shaft can be pulled out for examination, the heavy-duty bolts connecting the tail shaft and the main shaft need to be removed. And if there are complications, this task can take days to complete.
A race against time
When the crew of the vessel noticed metal debris in the lubrication system of the tail shaft, the shipping company decided the bulk carrier needed to immediately dock at the Blohm+Voss shipyard in Hamburg, Germany to ensure safe operation. However, during the removal procedure of the propeller shaft, further problems with the flange connection of the two shafts were noticed.
The vessel’s owners were under pressure to find a solution as quickly as possible. With a combination of the cost of repairs and the dry docking fees, unscheduled downtime can be extremely costly. And as the vessel is a commercial bulk carrier, it has tight schedules to meet: Any delays in shipment will lead to additional expenses.
Type: Bulk carrier
Year built: 2005
Deadweight tonnage: 170,012
Flag state: Marshall Islands
Home port: Majuro
Teaming up to find the fastest solution
The Greek shipping company contacted its partner J & E PAPADOPOULOS SA, the official distributor of SKF products in Piraeus, to find a solution and coordinate the repair project. The team of technicians at the shipyard identified the cause of the issue as shaft misalignment. Local engineers in Hamburg took the necessary measurements and advised both the shipyard and the ship owners on how to remove the old steel bolts without causing additional damage to the flange.
However, there were complications as the holes left by the old bolts were worn. They required on-site machining to ensure the new bolts would fit precisely and to prevent the problem reoccurring. Since the bolts needed to be installed and removed several times during the operation, J & E PAPADOPOULOS SA along with SKF Hellas recommended hydraulic bolts as the solution. These Supergrip Bolts also made it possible to perform the machining while the shaft was already back in the vessel, saving considerable time.
To minimize downtime, the new parts had to be delivered as quickly as possible, with all the required documentation from the classification society to state that the materials and components meet industry standards. The holes were precisely machined to ensure that the bolts fit perfectly.
The benefits of hydraulic bolts
- Considerable time savings during first installation and maintenance.
- Reduced risk of damage to the flange connection or coupling when removing the bolts.
- Fully re-usable– no need to make new bolts.
The big decision paid off
In the end, the rapid responses of all involved saved the shipping company significant time and money. Thanks to the hydraulic bolts, the service technicians were able to complete the repair operation in ten days—something that would not have been possible with conventional bolts. Despite the technical challenges and time pressure, a combination of global teamwork, high-quality components, and marine expertise saved the day.