Activation of Thordon Bearings’ inflatable emergency seal prevented a 70ft (21m) long workboat from certain sinking in February, following multiple shaft failures that damaged the vessel’s primary shaft seal.
The crew of the 2002-built twin-screw workboat activated Thordon Bearing’s TG100’s secondary seal during operations in the lower Mississippi River, when the vessel suffered catastrophic tailshaft failure in shallow waters north of New Orleans, U.S.A. The incident resulted in one of the tailshafts being pulled clear of the gearbox and almost completely out of the boat.
Jim Bright, Sales Manager, Thordon Bearings, said the situation was sudden and with no warning. “The starboard coupling bolts were sheared off, leaving the tailshaft with nowhere to go but out the back of the boat. Thankfully, the TG100 clamp ring prevented the shaft from being pulled any further back.”
Unlike other shaft seal designs that are prone to slipping on the shaft, the TG100 wedge design increases its holding capability in situations like this.
With the starboard shaft’s primary TG100 seal heavily damaged and the vessel taking on water, the crew managed to activate the TG100’s emergency secondary seal, which inflated as designed to re-seal the shaft.
The vessel was the very first workboat to be fitted with a TG100 seal in 2011.
“The primary seals performed flawlessly from the first day they went into service and we can now claim the same for the secondary emergency seal,” said Bright. “Despite the calamity going on, the emergency seal functioned as it should, preventing further water ingress and allowing the crew to safely manage the damage. The safe-return-to-port function almost certainly prevented this vessel from sinking.”
Following the incident, the owner, a large provider of marine transportation services in the U.S.A., with a fleet of more than 120 line-haul vessels, inland towing vessels, barges and tugs, needed to get the vessel back into service quickly. TG100 seals were once again specified.
“The incident was so violent we needed to replace the whole seal on the starboard side,” said Bright. “The owner decided to also upgrade the portside shaft with the current TG100 seal.”
The scope of supply also included the retrofitting of ThorPlas-Blue rudder and tiller bushings and Thordon RiverTough tailshaft bearings.
“The original cutlass bearings were found to be placing a tremendous amount of strain on shaft couplings due to very high wear rates, which could have been the root cause of the problem,” said Bright.
Commenting on the success of the TG100 seal in the US market, Scott Groves, Thordon Bearings’ Regional Manager, Americas, said: “The TG100 has an excellent performance record with hundreds of units now in service. It really is an important component to vessel safety, protecting not only the lives of the crew but also the vessel. The revolutionary design allows you to return safely to the nearest port if your primary seal is ever damaged.
“A number of Inland Towing companies have been replacing competitor products with the Thordon solution over the course of the past 12 months to reduce operational and maintenance costs,” said Groves. “The TG100 seal requires no replacement parts over its service life.”
Sea News, July 9