STS Container Crane Hoist Ropes: Beyond Broken Wires

By Dean McDonald, founder, Crane Rope Solutions

On container cranes (ship-to-shore or quay cranes) the conversation is always about hoist ropes. ZPMC usually delivers its cranes with a 6x36 rope made in Asia, and on cost per move that rope is simply unmatched, regardless of construction or where it's made. The other factor is kill rate: the share of ropes removed from service because they were crushed against a container. It's usually around 33%, so it's hard to justify spending even a penny more on a better rope.

A dangerous pattern

Of all the ports I've visited over the years, I've found a dangerous pattern that doesn't depend on location. East coast to west coast, Canada or the USA, almost every port I've spoken with that uses these ropes is only checking for wire breaks, and they very rarely find any.

The catch: these are six-strand uncompacted ropes on single-layer drums, running through a maze of sheaves from the drum, down the gantry to the spreader, back up to the trolley and back to the drum. The rope is rightly chosen for bending fatigue and made as flexible as possible, and as always with rope, that's a trade-off. By design, and because of how they're reeved, these ropes stretch and lose diameter. They don't break wires unless the diameter has already dropped dramatically, or they're poorly maintained and rusting.

Stretch and a reduction in diameter can mean the core is failing, and once the core fails, the chance of a sudden, catastrophic failure rises sharply.

To prevent this, measure rope diameter, and check for broken wires and every other discard criterion set out by your local governing standard and the crane OEM. The discard calculator combines the reduction in diameter with broken wires at the same spot: added together under ISO 4309 and CSA, worst single finding under ASME and API.

Rope life and berth availability

Beyond safety, there is a big benefit to optimizing rope selection. Rope changeouts can be one of the biggest reasons for planned outages on an STS crane, which cuts port productivity and berth availability. If berth availability is the biggest bottleneck to your port's revenue growth, choosing a rope that lasts longer, regardless of cost per container moved, can be a seven-figure change in revenue.

Email us and we'll show you a live demo using metrics from your own port.

From our inspections

Fresh grease applied over a dangerously corroded wire rope on a ZPMC ship-to-shore crane — **ZPMC ship-to-shore crane**Greasing over dangerously corroded wire rope. Fresh lubricant slows new corrosion but does not undo what is already there.

Steel rule across the grooves of a ZPMC ship-to-shore crane drum to measure the groove pitch — **ZPMC ship-to-shore crane**Measuring drum pitch: the spacing of the drum grooves, checked with a steel rule.

Drum of a port RTG crane with a wrong lay direction rope installed, the rope pattern worn into the drum — **Port RTG crane**Port RTG crane with a wrong lay direction rope installed. The rope's pattern is worn into the drum as negative impressions.

Two right-hand lay ropes spooled on a single-layer double drum of a LeTourneau RTG container crane — **LeTourneau RTG crane**Incorrect rope selection: two right-hand lay ropes on a single-layer double drum. The two halves of the drum are grooved in opposite directions, so they need one right-hand and one left-hand lay rope.

Crown wire breaks and corrosion on a wire rope from a Konecranes quay crane, with a broken outer wire lifting off the strand — **Konecranes quay crane**Crown wire breaks and corrosion: a broken outer wire lifting off the strand crown, with rust along the rope.

Hoist rope on a Konecranes quay crane with external damage from a container, marked with a red outline — **Konecranes quay crane**Hoist rope external damage from a container (marked): outer wires flattened and scraped where the rope was struck.

Negative rope imprints in the hoist drum grooves of a Liebherr RTG container crane — **Liebherr RTG crane**Negative rope imprints worn into the hoist drum. A new rope laid into these grooves wears on the imprint edges.

Non-standard swaged wire rope end at the drum anchor of a LeTourneau RTG container crane — **LeTourneau RTG crane**Non-standard swaged rope end at the drum anchor. Order the replacement to the exact end dimensions in the OEM specification, not by the rope size alone.

Worn flange on a trim beam deflection sheave of a Liebherr P125L ship-to-shore container crane — **Liebherr P125L ship-to-shore crane**Trim beam deflection sheave worn on the flange. Wear like this changes the groove profile and wears the rope's outer wires.

Slight negative rope imprints in a boom hoist deflection sheave of a ship-to-shore container crane — **Liebherr P125L ship-to-shore crane**Slight negative rope imprints in a boom hoist deflection sheave. Caught early, the sheave can be replaced before it marks a new rope.

More wire rope damage photos

Need a replacement rope? Find your crane for the diameter, length and part number of every winch, or call 604-813-9473.

Container crane hoist ropes: why checking for broken wires isn't enough

A dangerous pattern

Rope life and berth availability

From our inspections