Wire rope is a machine — dozens or hundreds of wires moving against each other as the rope bends and loads. The construction code on the certificate (6×19, 6×36, IWRC, RRL) describes exactly how that machine is built, and decoding it tells you where the rope belongs.
Reading the Code
6×19 means 6 strands of (nominally) 19 wires; 6×36 means 6 strands of 36 wires. These are classes — a 6×19-class rope may actually be 6×26WS — grouped by wire count per strand. The trade-off is fundamental: fewer, larger wires resist abrasion; more, smaller wires bend easier and resist fatigue. 6×19 for drag lines and abrasive service; 6×36 for running rope over sheaves and general hoisting, especially above 1" diameter.
Core: IWRC vs Fiber
The core supports the strands. IWRC (independent wire rope core) adds ~7% strength, resists crushing on multi-layer drums, and holds up at temperature — the industrial default. Fiber core ropes are more flexible and hold lubricant well but crush on drums and are limited to ~180°F.
Lay, Grade & Finish
Right regular lay (RRL) is the standard — wires appear to run parallel to the rope axis, giving the best crush and rotation behavior. Lang lay wears longer over sheaves but must have both ends fixed. Grades run IPS → EIPS (+15%) → EEIPS (+10% more); EIPS is today's standard sling and hoist rope. Galvanizing buys corrosion resistance at a small strength cost; bright (uncoated) rope with proper lubrication covers most plant service. Rotation-resistant constructions (19×7, 35×7) are for single-part crane hoist lines where the load must not spin — and have their own strict handling rules.
Strength Snapshot (6×19 EIPS IWRC)
| Diameter | Nominal breaking strength |
|---|---|
| 3/8" | 7.55 tons |
| 1/2" | 13.3 tons |
| 5/8" | 20.6 tons |
| 3/4" | 29.4 tons |
| 1" | 51.7 tons |
Breaking strength is not working load — design factors of 5:1 apply to slings and standing rope. Always work from WLL.
D/d Ratio
Every bend costs strength: a rope bent around a diameter 10× its own retains ~86% efficiency; around 2× its own, barely 65%. Size sheaves, pins, and load edges accordingly — this is the most common hidden de-rating in field rigging.
Rope Cut, Spliced & Certified
Wire rope by the foot, flemish-eye slings, and assemblies with certs — from our Texas warehouse. Construction, diameter, length, and end terminations into the quote form at the top of the page — quotes answered during business hours.