Undetected Corrosion and Wear Lead to Equipment Failure on Cargo Ship -NTSB

A recent incident involving a cargo ship in Houston has brought attention to the importance of regular maintenance and inspection of equipment. According to the National Transportation Safety Board (NTSB), undetected corrosion and wear led to an equipment failure on the cargo ship Thorco Basilisk while offloading cargo at the Greensport Terminal on the Houston Ship Channel.

On July 23, 2022, the ship was offloading a wind turbine component when the hoisting wire rope on one of the cargo cranes failed, causing the component to drop onto the vessel’s cargo hold tween deck. Fortunately, no injuries were reported, but damages to the ship and cargo were estimated to be between $3-5 million.

An examination of the hoisting wire rope revealed significant external corrosion and wear that had gone unnoticed. The grease on the rope had concealed the visible signs of corrosion. While annual visual inspections were conducted on the wire ropes, they did not detect the underlying corrosion below the grease.

The wire rope, which had been in use for 9 years, was still within the standard 10-year period of use. However, a post-casualty examination determined that the wire rope was near the end of its service life and should have been discarded. The operating company has since updated their maintenance system to require crane wire rope replacement every 5 years.

The NTSB report highlighted the challenges of maintaining high-strength steel wire ropes on vessels due to the corrosive effects of saltwater and humid ocean air.

“A deteriorated wire rope directly affects a crane’s ability to safely and reliably handle loads up to its rated capacity (safe working load). Therefore, diligent inspection, maintenance, and management of wire ropes are essential. Working wires should be changed at recommended intervals, or more frequently, depending on operating conditions and use,” the report said.

This incident underscores the importance of proactive maintenance practices and serves as a reminder to the maritime industry to remain vigilant in ensuring the safety and reliability of equipment on board ships.

The NTSB report comes after the U.S. Coast Guard last week issued a safety alert warning about the hazards associated with crane wire ropes on ships, seemingly related to the same incident.

The NTSB report can be found here.

Read more: gCaptain’s full coverage of marine casualty reports

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