6.5 Fibre Rope Slings & Natural Fibre Ropes
Key Takeaways
- Fibre rope slings are the traditional form of textile sling, produced from cut lengths of natural fibre rope—manila, sisal, or hemp—which are hand-spliced to form eyes or endless loops.
- Natural fibre slings are less pliable and bulkier than flat woven webbing slings and roundslings, and they present a hard point contact to the load, though less severe than chain or wire rope.
- Single-leg, multi-leg, and endless fibre rope slings can be produced; where multi-leg assemblies attach eyes through a master link, thimbles are advised to protect the eyes.
- Natural fibres are difficult to identify visually and lack the standardized colour-coded labels of synthetic slings; they are vulnerable to rot, mildew, moisture, and chemical attack.
- Use of fibre rope slings has declined in favour of flat woven webbing slings and roundslings, but they may still be found in service and must be inspected for rot, stiffness, broken yarns, and abrasion before every use.
Fibre Rope Slings & Natural Fibre Ropes
Long before polyester webbing and high-modulus polyethylene existed, loads were slung with natural fibre rope. Fibre rope slings are the traditional form of textile sling, with origins in the earliest recorded history of lifting equipment. Although their use has declined in favour of flat woven webbing slings and roundslings, they may still be found in general use throughout industry—so inspectors and riggers must know how they are made, how they behave, and when to reject them.
1. Materials & Construction
Natural Fibres
Fibre ropes are produced from grasses and plant leaves that are spun into yarns, twisted into strands, and laid into rope. Common natural fibres include:
- Manila (abaca leaf fibre): the strongest and most durable of the natural lifting fibres.
- Sisal: similar to manila but slightly lower strength; widely used for general-purpose ropes.
- Hemp: soft-handling traditional fibre, now rare in lifting service.
(Man-made fibre ropes—polyamide, polyester, polypropylene—follow similar rope constructions but belong to the synthetic sling family of Sections 6.1-6.2; high-performance HMPE fibres are covered in Section 6.2.)
Sling Assembly
Fibre rope slings are produced from cut lengths of rope which are hand spliced:
- Single-leg: eyes hand-spliced at each end of a rope length.
- Endless: one cut end spliced to the other, forming a continuous loop.
- Multi-leg: the eye of each leg is made through a master link; where this is done, the use of thimbles is advised to protect the rope eyes.
Eyes are formed by bending the rope into a loop, separating the strands at the rope end, and tucking them back into the standing part against the lay so they lock under load. Splicing requirements differ between rope types because of differing coefficients of friction—another reason splicing must be left to trained hands.
2. Handling Characteristics & Limitations
| Characteristic | Fibre Rope Sling | Comparison |
|---|---|---|
| Pliability | Less pliable than webbing slings and roundslings; bulky to handle | Synthetics conform closely to the load |
| Load contact | Presents a hard, point contact to the load | Less severe than chain or wire rope, but harsher than webbing |
| Moisture | Absorbs water; swells, stiffens, and loses strength | Synthetic PES/PP are largely unaffected |
| Rot & mildew | Vulnerable to biological decay if stored damp | Synthetics do not rot (but suffer UV and chemical limits) |
| Identification | Fibres look alike; no standardized colour-coded label system | Synthetic slings carry BS EN 1492 labels and colour codes |
| Temperature & chemicals | Limited; acids, alkalis, and heat degrade natural fibres | Choose sling material to match the environment (Section 6.1 matrix) |
The Identification Problem
Visually, the various natural fibres appear much the same, making material identification extremely difficult. There is no harmonized colour-coded label scheme for natural fibre slings comparable to BS EN 1492. If a fibre rope sling's material, WLL, or certification cannot be positively established, it must be treated with the same zero-tolerance discipline applied to unlabelled synthetic slings: withdraw it from service.
3. Deterioration Modes & Inspection
Natural fibre slings degrade biologically and mechanically. A thorough pre-use inspection combines sight, touch, and smell:
- Rot and mildew: Musty odour, dark staining, or powdery fibre breakdown—accelerated by damp storage. Discard immediately; rot cannot be assessed for residual strength.
- Stiffness and brittleness: Old, wet-then-dried natural rope becomes rigid and inelastic; stiff fibres snap under shock. Reject.
- Broken yarns and abrasion: Frayed or cut strands reduce effective diameter; reject on significant external wear or any cut strands in a load-bearing area.
- Chemical contamination: Contact with acids, alkalis, or solvents weakens natural fibres without always leaving visible signs—if contamination is suspected, discard.
- Splice integrity: Any slippage, opening, or strand withdrawal at the hand-spliced eyes requires immediate rejection.
Storage
Store natural fibre slings dry, ventilated, and off the ground, away from direct heat, sunlight, and chemicals. Never store them damp—moisture trapped in the coils guarantees mildew.
4. Where Fibre Rope Slings Fit Today
Their decline is not accidental: flat woven webbing slings spread load across the full webbing width, roundslings protect a parallel core inside a woven jacket, and both carry unambiguous BS EN 1492 identification. Natural fibre rope slings survive mainly in legacy stores, agriculture, and traditional trades. When one is encountered:
- Confirm identification and rating before use—no guessing.
- Inspect for rot, stiffness, broken yarns, and splice condition.
- Apply the same hitch mode factors as any sling (choke derating, angle effects—Chapter 9).
- When in doubt, replace it with a certified synthetic sling rather than debate its residual strength.
Which natural fibres are commonly used to produce fibre rope slings?
How are the eyes of fibre rope slings formed, and what protects the eyes of multi-leg assemblies at the master link?
A pre-use inspection of a natural fibre rope sling finds a musty odour, dark staining, and powdery fibre breakdown. What action is required?