Wire rope selection guide covering construction (6x19, 6x36, 8x19, 19x7, 35xK7), core (FC / IWRC), lay direction (RH / LH regular vs Lang lay), tensile grade (1770 / 1960 / 2160 MPa), preformed vs non-preformed, and coating (galvanised / stainless / plastic-jacketed). Includes minimum breaking load (MBL) tables per ISO 2408 for common diameters, D/d ratio guidance per ISO 4308-1 for cranes and hoists, discard criteria per ISO 4309, and end-termination options (poured socket, swaged, wedge, thimble + Flemish eye).
A wire rope specification is written in a defined order: nominal diameter × construction / core / grade / coating / lay. For example "16 mm × 6 × 36 WS + IWRC / 1960 / A / RRL" reads as 16 mm nominal diameter, 6 outer strands of 36 wires in Warrington-Seale layout, independent wire-rope core, tensile grade 1960 MPa, class A galvanised, right-hand regular lay. Every element affects the working characteristics and the correct code for a given duty.
| Construction | Wires per strand | Common duty | Handling |
|---|---|---|---|
| 6 × 7 | 7 | Standing rigging, guy wires | Stiff, poor fatigue |
| 6 × 19 Seale | 19 | General lifting, mine hoist | Balanced abrasion vs. fatigue |
| 6 × 19 Filler wire | 25 | Elevator, general lifting | Improved fatigue |
| 6 × 25 Filler wire | 25 | General crane hoist | Widely stocked |
| 6 × 36 Warrington-Seale | 36 | Crane, deck machinery, offshore | Best flexibility, moderate abrasion |
| 8 × 19 / 8 × 25 | 19 / 25 | Small-diameter drum, elevator | Very flexible; requires IWRC |
| 19 × 7 non-rotating | 7 (per strand) | Free-fall crane hook lines | Torque-balanced, resists spin |
| 35 × K7 (compacted) | 7 (compacted) | Heavy lift, tower crane, offshore | Rotation-resistant, high MBL/dia |
Fibre core (FC) — traditional sisal or polypropylene, ~10% lower MBL than IWRC at the same diameter; used only where the rope stays dry and unloaded. Independent wire-rope core (IWRC) — a small 7 × 7 wire rope inside the outer strands; standard on all industrial and marine crane hoist ropes. IWRC ropes withstand higher lateral crush from drum layers and hold their diameter under overload.
| Grade | Nominal tensile | Typical use |
|---|---|---|
| 1570 MPa | 1570 N/mm² | Legacy elevator, some standing rigging |
| 1770 MPa | 1770 N/mm² | General industrial hoist |
| 1960 MPa (Extra Improved Plow Steel) | 1960 N/mm² | Standard for cranes and deck machinery |
| 2160 MPa | 2160 N/mm² | Heavy lift, mobile crane boom hoist |
| 2500 MPa | 2500 N/mm² | Compacted-strand offshore hoist |
Values below are indicative for 6 × 36 IWRC 1960 MPa. Confirm the actual MBL against the rope manufacturer's test certificate for procurement and lift planning.
| Nominal diameter | Metallic area (mm²) | Approximate mass (kg / 100 m) | Indicative MBL (kN) |
|---|---|---|---|
| 8 mm | 30.7 | 26.8 | 52.7 |
| 10 mm | 47.9 | 41.9 | 82.4 |
| 12 mm | 69.1 | 60.4 | 119 |
| 14 mm | 94.0 | 82.2 | 162 |
| 16 mm | 123 | 107 | 211 |
| 18 mm | 155 | 136 | 267 |
| 20 mm | 192 | 168 | 329 |
| 22 mm | 232 | 203 | 398 |
| 24 mm | 276 | 242 | 474 |
| 28 mm | 375 | 329 | 645 |
| 32 mm | 490 | 430 | 842 |
Rope fatigue life is governed by the ratio of sheave pitch diameter (D) to rope nominal diameter (d). ISO 4308-1 specifies minimum D/d ratios based on crane duty class (M1 through M8). A M5 crane hoist typically demands D/d ≥ 16 for the boom head sheave, ≥ 14 for the drum. Halving the D/d ratio reduces the rope's bending fatigue life by an order of magnitude — sheave selection is the single biggest driver of rope replacement interval.
| Termination | Efficiency | Field-installable? | Typical use |
|---|---|---|---|
| Poured socket (spelter or resin) | 100% | Yes (skilled) | Crane hoist, elevator |
| Swaged (mechanical) | 95% | No (press required) | Bridge, offshore, permanent slings |
| Wedge socket | 80% | Yes | Removable termination, mobile crane |
| Flemish eye + steel sleeve | 90% | No (press required) | Slings, tow lines |
| Fibre-core tucked splice | 85% | Yes (skilled) | Legacy standing rigging |