How to order a replacement crane rope

By Dean McDonald, founder, Crane Rope Solutions

The quickest way to order the right replacement crane rope is by the crane manufacturer’s (OEM) part number. One part number fixes every detail that matters: nominal diameter, construction, diameter tolerance, lay direction and lay type, wire grade, minimum breaking load (MBL), finish, length and end fittings.

If you don’t have the part number, send us:

• the crane make, model and serial number
• which rope it is (main hoist, auxiliary or whip line, boom hoist, luffing rope, kelly or crowd rope)
• a photo of the rope tag, or the original OEM rope specification from the manual

Please don’t send only the mill certificate from the last replacement rope. See why below.

Send us those three things and we will quote the rope: dean@craneropesolutions.com or 604-813-9473.

The ten details behind every crane rope part number

Why order by the OEM part number?

An OEM part number describes the rope the crane was designed and tested with. Behind most part numbers there are usually several approved ropes from different rope makers. For example, one rope may be fully compacted with a lower wire grade, and another may have a higher grade with only the outer strands compacted.

Neither is right or wrong. Rope forensics on your old rope, meaning how it actually failed, tells us whether your next rope would last longer going up or down in grade or construction.

Can I use an imperial rope on a metric drum?

No, not on a multi-layer drum. Buy the size your drum was built for.

A 1-1/8 in rope is 28.58 mm, which is 2.1% bigger than a 28 mm rope. That can be the difference between a rope that spools cleanly through every layer and one that leaves gaps halfway across the second layer, or kicks over wrongly on the third.

Even a 1% mismatch can make a rough-terrain crane rope wrap less neatly and dive into the layer below. Those cranes are often run by newer operators, so a spooling problem is more likely to turn into damage. The price difference between the metric and imperial rope is almost nothing. Confirm whether your drum is metric or imperial, and stick with it.

What do 35x7, 8x31 and 6x36 mean?

The first number is the number of strands. The second is the number of wires in each strand. A 35x7 rope has 35 strands of 7 wires each.

Letters added to the construction tell you more:

• K: compacted strands (flattened outer wires for more contact area and crush resistance)
• IWRC or WSC: independent wire rope core, or wire strand core
• EPIWRC: a steel core covered with a polymer (plastic) layer
• WS, S, W, F: the strand type (Warrington-Seale, Seale, Warrington, Filler)

Every abbreviation you’ll see on a mill certificate or OEM rope specification is explained in our wire rope abbreviations guide.

What is a Category 1 rotation-resistant rope?

A Category 1 rotation-resistant rope has at least 15 outer strands and at least three layers of strands, and has little or no tendency to rotate under load. 35x7 is the typical example. Most crane hoist ropes reeved through multi-sheave hook blocks are Category 1.

Ordinary, non-rotation-resistant ropes such as 6x36 or 8x31 usually have 6 to 9 outer strands. They are used where both rope ends are fixed against turning, or the rope runs in a single part.

What diameter tolerance does my crane rope need?

Diameter tolerance is how much bigger than nominal the rope is allowed to be. On multi-layer grooved drums it is the most important detail in rope selection.

A 26 mm rope with a tolerance of 0 to +5% can measure anywhere from 26.0 mm to 27.3 mm along its length. On a drum 25 wraps wide, 1.3 mm extra per wrap adds up to 32.5 mm by the far flange, and the next layer won’t spool properly.

Typical tolerances we see:

• Most grooved (Lebus) drums: the grooves are typically cut to a pitch 5% over the nominal rope diameter, and these cranes usually need +2% to +4%.
• Large wind cranes (Liebherr LR and LG series, Demag CC): as tight as +2.9% to +3.5%.
• Some offshore pedestal cranes: +3.5% to +4.5%.
• Plain or shimmable drums (Seatrax cranes, spud winches, barge anchor winches): tolerance matters less, because shims let you adjust the drum width.

The more layers on the drum, the tighter the tolerance needs to be. By the fourth or fifth layer it is critical.

Related: Diameter tolerance, and why a rope stops spooling

Right-hand or left-hand lay rope?

Lay direction is right (Z) or left (S). The right one depends on which side of the drum the rope is anchored to, whether the drum is overwound or underwound, and sometimes on the reeving.

On some multi-layer winches the lay direction can be changed if the lay you need isn’t available. Only do this after checking with your rope supplier or the crane manufacturer. The wrong lay direction for the reeving can open up or tighten the rope’s structure in service.

Regular lay or Lang’s lay: which lasts longer?

On multi-layer drums, Lang’s lay ropes usually last longer. Regular (ordinary) lay ropes are more stable, tolerate fleet angle better and resist rotation better.

• Regular lay: the wires are laid in the opposite direction to the strands. It tolerates a wider fleet angle onto the drum, resists torque and shock loads better, and is far more rotation resistant. A regular lay rope can stay stable for up to 100 m more lift height than the same rope in Lang’s lay.
• Lang’s lay: the wires and strands are laid in the same direction. The rope is rounder, which spreads the contact pressure between wraps on the drum. That is why most multi-layer winches use Lang’s lay wherever they can.

Lang’s lay ropes need extra care at installation. They twist more easily, and if the structure is opened even slightly, they crush more easily.

Lang’s lay ropes also wear more evenly. So once the first broken wires appear, the time to discard is much shorter than on a regular lay rope. Shorten your inspection interval once you see the first breaks.

Alternate lay ropes, which mix regular and Lang’s lay strands, came before compacted strands as a way to improve crush resistance on boom hoists. Most owners now replace them with compacted ropes, which last longer, are easier to inspect and are easier to get.

1960 or 2160 grade: which is better for a crane rope?

Wire grade is the tensile strength of the wire in N/mm². Each step up (1770, 1960, 2160) adds about 10% strength and makes the rope more rotation resistant, but reduces ductility and fatigue resistance. Higher is not automatically better.

• Common crane grades: 1960 and 2160. Ropes are also made in 1770, 2360 and 2560.
• Grades are mixed inside a rope. A “1960” rope can contain softer 1770 wires where ductility is needed and harder 2160 wires where strength is needed.
• Rope shops often stock only 2160 ropes, so one rope covers the MBL for more crane models. If the grade is higher than the winch needs, you lose fatigue life and get a shorter-lived rope.
• Harder wire is harder to draw to size. Dies wear faster, so wire diameter is harder to hold consistent through a long production run. The result can be poor spooling as the layers build up and the rope beds in.
• Sheave material matters. Rope grade interacts with the steel or iron used in metal sheaves. When you replace a rope on a crane with metal sheaves, tell your rope supplier. A better-matched grade is often available for the same price or close to it.

Why you shouldn’t order from the old mill certificate

Send the OEM part number or the OEM rope specification, not the mill certificate from your last replacement rope. Each round of quotes from a mill certificate tends to push the MBL and wire grade higher, and rope life lower.

Here’s a pattern I see all too often:

1. The original OEM rope: MBL 790 kN, grade 1960. It lasted 10 years.
2. The first replacement: the owner sends the old mill certificate. Suppliers treat 790 kN as the minimum and supply a 2160 rope from stock at 811 kN. It lasted 8 years.
3. The second replacement: the owner sends the 811 kN certificate. Fewer suppliers can quote, and the owner ends up with a different construction at 820 kN in grade 2360. The rope is too stiff and brittle for the winch. It lasted 2 years.

All of that could have been avoided by quoting the OEM part number or specification.

What design factor does my crane rope need?

The required MBL is set by the design factor of the winch: the rope’s minimum breaking load divided by its maximum line pull. North American mobile crane standards ask for 3.5:1 on most running ropes and 5:1 on rotation-resistant ropes. European mobile cranes are typically designed around 4.5:1 for hoist ropes.

A few details that change the answer:

• Synthetic rope: CSA Z150:20 asks for 5:1 on a drum or sheave and 4:1 when standing.
• Boom erection and lowering: CSA Z150:20 (4.7.1.3) allows lower factors while the boom is being raised or lowered: 3:1 for running ropes and 2.5:1 for standing ropes.
• Weak end fittings count against you: if a termination is less than 80% efficient, CSA Z150:20 (4.7.1.1) and API Spec 2C both require the loss to be built into the design factor. That is one more reason to think twice about wedge sockets (see end fittings below).
• API Spec 2C works the factor out from the rated load and the crane’s dynamic coefficient, so offshore crane ropes get a higher factor on small lifts and a lower one on heavy lifts.

That raises a question for owners of European-built cranes working in North America: a rope sized to 4.5:1 for the EN design may not meet the 5:1 that CSA Z150 and ASME B30.5 ask for on rotation-resistant hoist ropes. Check with your rope supplier and the crane manufacturer before ordering.

Bright or galvanized crane rope?

Choose bright rope unless the environment is corrosive. Corrosive means offshore salt and humidity, or open-pit and underground potash mining.

• Galvanized ropes are nearly as strong as bright ropes today. Most galvanized crane rope is made from drawn-galvanized wire, where zinc goes on before the final drawing. Older ropes used final-galvanized wire, galvanized after drawing, and were only about 80% as strong as bright rope.
• The trade-off is bending efficiency and diameter consistency. The zinc coating adds small imperfections, and as it wears, the gaps between wires open up. That can let a rotation-resistant rope come out of balance.
• The difference adds up through a hook block. Galvanized rope loses about 2% bending efficiency against bright. That is small over one sheave. Through a hook block with 30 or more sheaves, it multiplies: the block can lift higher on one side, creating fleet angle and torque where the rope rides up the side of the groove.

Where galvanized rope is the right choice:

• Offshore pedestal cranes: main hoists on two parts of line, single-part auxiliary lines, and boom hoist or luffing ropes running on oversized sheaves that make up for the lost efficiency.
• Deep foundation kelly winches (Bauer BG, Liebherr LB, Soilmec SR): the kelly rope bends over only one or two sheaves on a single part, so the efficiency loss doesn’t matter. Dirt and aggregate are a bigger threat than humidity, and a rope with less grease picks up less dust.
• Tower cranes: case by case. Flat-top, luffing and hammerhead tower cranes can run near duty cycle while flying tables or forms, which favours bright rope. But they are harder to reach for maintenance and sit close to concrete pours and site dust, which favours galvanized.

Which end fittings should a crane rope have?

Drum end: almost always a plain end, brazed and tapered (welded) or seized with wire so the rope keeps its shape while it is pulled in.

Tip: ask for a welded pull link (pad eye) on the drum end. It costs very little from the rope supplier, and it makes pulling the new rope in easier and safer than a wire mesh grip (“rope sock”). Mesh grips are meant for straight-line pulls and have to be fitted perfectly. Installations are complex jobs where things go wrong, and I’ve been on jobs, or involved in investigations afterwards, where mesh grips failed. The cause was usually poor fitting or too much line tension from the spooler, but I’ve seen it too often to recommend them. A welded eye done to procedure by a competent person has never failed me.

Dead end (the other end):

What certificates come with a crane rope?

• Mill certificate (standard). Shows nominal diameter, construction, lay type and direction, and grade. Ask for the actual measured diameter too. It isn’t always on the certificate, but it lets you check the rope is within the maker’s tolerance.
• EN 10204 3.1 certificate. Issued by the rope maker’s own inspection department, independent of production. Many European makers supply one as standard.
• EN 10204 3.2 certificate. Adds sign-off by a third-party inspector or the buyer’s representative, such as DNV, ABS or Lloyd’s. It costs extra and needs to be ordered with the rope.
• ABS, DNV and CSA certificates are available on request.

Do crane rope end fittings need to be proof tested?

Yes. Poured and swaged end fittings are proof loaded after they are fitted to the rope. How hard depends on the standard, and under ASME B30.30-2023 it also depends on whether the fitting was put on in a rope shop or in the field.

What this means when you order:

• Shop-made assemblies (a rope with the button or socket already poured or swaged) should arrive with a proof test certificate showing 40 to 50% of MBF.
• Fittings poured or swaged on site are proof loaded against the crane’s rated line pull, not the rope’s breaking force. Under ASME B30.30-2023 that test has to reach at least 95% of maximum rated line pull.
• CSA Z150:20 has one rule for both: follow the rope or fitting maker, and never exceed 50% of breaking strength.
• Ask for the proof test certificate with every terminated rope, and keep it with the rope’s records.

What changed in ASME B30.30-2023?

The 2023 edition split proof testing of wire rope terminations into shop-made and field-made fittings. For steel wire rope, ASME B30.30-2019 only covered replacement running-rope terminations made in the field:

Other rope changes in the 2023 edition include swaged sockets now allowed on fibre core, Lang’s lay and Category 3 rotation-resistant ropes when a qualified person approves, a new table of diameter-reduction discard criteria, and more required items on the rope certificate.

Don’t just choose a rope, choose a rope person. The right person can do more for your rope life than the best rope installed and maintained without good guidance. Always check with them that you comply with your local standards.

How fast can a replacement crane rope ship?

A well-organised shop focused on crane ropes can usually cut and terminate a rope within a couple of hours if it’s urgent. Poured sockets need time for the resin to cure before proof testing. That is usually an hour or two at room temperature and longer in the cold, so allow up to 24 hours in the worst case.

Frequently asked questions