Shaft bearing retrofits prevent pollution from terminal service vessels

Seven service vessels operating at single point mooring (SPM) terminals of the Sumed Pipeline have new seawater-lubricated bearing systems from Thordon Bearings.

This pipeline runs from the Ain Sokhna terminal in the Gulf of Suez to offshore Sidi Kerir port, near Alexandria in the Mediterranean Sea, providing an alternative to the Suez Canal for transporting oil.

Nefertiti Marine’s Yard-K shipyard in Rosetta Nile replaced the oil-lubricated tailshaft bearings on these seven 1976–built, 18-m SPM service vessels in 2022, completing the final one in December. These were replaced with Thordon’s SXL, a water-lubricated tailshaft arrangement that negates the need for an aft seal and only has a forward seal between the engineroom and the open system.

These vessels assist tankers in loading shipments from the Sumed oil pipeline including line handling and manoeuvring at the SPMs.

Nefertiti Marine engineering manager Karim Abd El Karim explained why the change to SXL was required.

“Oil was leaking from the shafts, and the operator was looking for a longer-lasting bearing solution, resistant to abrasive waterways,” he said. “We proposed the SXL material as the right solution to meet all performance and environmental needs. The vessel owner agreed.”

SXL tailshaft bearings were machined for shaft diameters of 95 mm. Nefertiti Marine provided classification approval drawings and advised on the installation process through to commissioning.

“The success of that first installation, together with the reliability and availability of Thordon’s SXL bearings, lead times and Nefertiti Marine’s engineering expertise, gave us the confidence to convert all these special purpose service boats to seawater-lubrication,” said Mr Karim.

“The perennial problem of worn aft seals leaking oil into the sea and canal has now been solved.”

Thordon Bearing’s SXL and ThorPlas-Blue non-metallic bearings are ideal solutions for tugboat, dredger and other coastal workboat operators looking to easily convert their closed oil-polluting seal system to solutions more in-line with their environmental, sustainability and governance goals.

“Based on the success of that first installation, the other vessels in the fleet spent less time in drydock, reducing vessel downtime considerably,” said Thordon Bearings’ regional manager for northern Europe and Africa, Neil McDonald. “The company is now looking at converting greased deck equipment bearings and rudder bearings to our grease-free ThorPlas-Blue bearings.”

An open SXL water-lubricated bearing system is less expensive than new, white-metal bearings that operate with two oil seals.

Thordon recommends vessel operators looking to convert from oil lubrication to water lubrication should do so before existing shaft liners are too worn, as it may be possible to use existing shaft liners and simply replace the bearings.

“We are seeing increased market interest for Thordon’s water-lubricated and grease-free seal and bearing products across the Middle East,” said Mr McDonald.

“With the completion of these conversions, Thordon continues to grow its retrofit market, while increasing workboat reliability and improving the environment in the waters of the Middle East.”