Crane Wire Failure: NTSB Report MIR-26-11

Crane Wire Failure: A $3.8 Million Warning on Internal Wire Corrosion | NTSB Report MIR-26-11

What Happened: On April 3, 2025, the offshore construction vessel Island Venture was using its subsea crane to lift a 338-metric-ton wire reel off the main deck of the offshore supply vessel C-Enforcer. As the load was hoisted, the crane’s wire snapped, sending the massive reel crashing onto the C-Enforcer’s main deck. Fortunately, no injuries or pollution occurred, but the impact caused an estimated $3.8 million in damages to both vessels.

Investigations revealed that the 10-year-old hoisting wire failed due to severe internal and external rust. The wire had been regularly submerged in saltwater during subsea operations. Despite passing a break test nine months prior and undergoing routine freshwater rinses, the internal corrosion progressed faster than anticipated. Because of the previous break test results, the crane had been derated to a 320-metric-ton Safe Working Load (SWL). To lift the 338-metric-ton reel, the operator had to activate an override function. The internally weakened wire could not handle the excess load, leading to the sudden failure.

Immediate Operational Checks:

Officers and lift teams should immediately verify the condition of their heavy lifting equipment:

• Inspect all hoisting wires for signs of external rust, paying special attention to wires heavily utilized in submerged environments.
• Review high-pressure lubrication logs for subsea cranes to ensure grease is fully penetrating the wire core according to manufacturer recommendations.
• Verify that no planned lifts require overriding a crane’s programmed Safe Working Load (SWL) limits, especially if the wire has been derated due to fatigue or previous break tests.

Wire Inspection & Replacement Guidelines:

When inspecting a crane wire, meticulously examine its entire length, especially sections repeatedly exposed to saltwater or resting on sheaves. Clean away old grease to expose the inner strands. Run a thick-gloved hand along the wire to feel for snags from broken wires. Replace the wire immediately if you detect localized strand breaks, a significant reduction in diameter, severe rust pitting, or a dry, degraded core causing visible changes in the rope’s shape.

Lessons Learned:

• Enhance Wire Maintenance: Submerged crane wires require strict adherence to high-pressure lubrication schedules to prevent trapped salt water from causing internal corrosion.
• Respect Derated Cranes: Never treat a derated SWL as a flexible limit. Overriding safety systems to lift loads beyond the reduced SWL places unacceptable stress on weakened components.
• Monitor Degradation Rates: Recognize that corrosion can accelerate rapidly. If a wire shows reduced breaking strength during testing, its deterioration rate might be faster than standard maintenance intervals can handle.
• Improve Post-Submersion Care: Surface-level freshwater rinsing is often not enough to clear salt water from deep within the wire strands.

Specifying and Ordering Replacement Crane Wire
When it comes time to order a replacement wire, you cannot rely on guesswork or simply ordering what “looks right.” The wrong wire can lead to catastrophic failure, similar to the incident on the Island Venture. As officers, your first and only definitive reference for ordering replacement wire is the crane manufacturer’s original equipment manual (OEM) and your vessel’s approved lifting gear register.

When you look at the specifications, you will see a string of numbers and letters. Here is how marine wire ropes are specified:

• Diameter: This is the thickness of the wire rope. It must perfectly match the grooves on your crane’s sheaves and winch drum to prevent crushing or excessive wear.
• Construction: This describes how the wire is built, usually written as a formula like “6×36 WS.” E.g. This means there are 6 outer strands, and each strand is made of 36 individual wires arranged in a Warrington Seale (WS) pattern.
• Core Type: The center of the rope supports the outer strands. For heavy marine lifting, this is often an Independent Wire Rope Core (IWRC).
• Grade and Minimum Breaking Load (MBL): This defines the tensile strength of the steel used (e.g., 1960 N/mm²) and the minimum force required to break a new rope. Your chosen wire must meet the Safe Working Load (SWL) safety factor required by your Classification Society, or company policies.
• Lay: This specifies the direction the strands twist (Right or Left) and how the wires twist within those strands (Regular lay or Lang lay). Using the wrong lay can cause the wire to untwist under load or spool improperly on the drum.
• Finish: For marine environments, the wire is typically specified as galvanized to resist saltwater corrosion, rather than “bright” (uncoated) steel. It will also specify the factory lubrication applied during manufacturing.

Always ensure the new wire comes with a proper manufacturer’s test certificate, and that the certificate is logged in your vessel’s planned maintenance system (PMS) before the wire is put into service.

Tags:

Marine Safety, Crane Failure, Wire Rope Corrosion, Heavy Lifting, Subsea Operations

Official Report:

Read the official NTSB Report MIR-26-11 here