Don’t Twist It: Preventing Sling Twist and Torsion in Rigging Operations

Sling twist is one of the most commonly overlooked causes of rigging failures, sling wear and load instability. Whether you’re using synthetic webbing, wire rope, or chain slings, improper setup or load rotation can result in torsion (twisting tension) that severely compromises safety.

In this week’s ELEVATIP, we explore how sling twist occurs, what hazards it introduces, and how to prevent it through good rigging practices and equipment awareness.

What Is Sling Twist and Why Is It Dangerous?

Sling twist occurs when the lifting sling — regardless of material — becomes twisted along its axis during a lift. This may happen when:

  • The load rotates during elevation.
  • The rigging setup is not aligned with the load’s COG.
  • The crane hook spins under tension.
  • The slings are installed with a pre-existing twist.

Twisting places uneven stress across the sling fibres or links, reducing their effective strength and accelerating wear. In extreme cases, it can cause a catastrophic sling failure.

Key Risks of Sling Twist

  •  Load Instability
    Twisting forces can cause the load to rotate or tilt unpredictably mid-lift.

  • Premature Sling Damage
    Twist concentrates strain on edges, accelerating abrasion or crushing in synthetic and wire slings.

  • Reduced Sling Capacity
    Manufacturers rate slings for straight-line loading. Twist reduces load-bearing capability.

  • Hook or Shackle Failure
    If the load rotates, it may bind against hardware components not designed for torsion

Common Causes of Sling Twist

  1. Misaligned Load and Hook
    When the crane hook is not centred over the load’s COG, the lifting action pulls at an angle, causing the load to rotate — and the slings to twist.
  2. Uneven Sling Lengths
    When slings are of differing lengths, one takes more tension, and the imbalance may cause load rotation.
  3. Swivelling Without Swivels
    Attempting to rotate a load without a proper swivel device at the hook or shackle can induce torsion in the slings.
  4. Inadequate Pre-Lift Check
    If slings are placed on the load already twisted, the issue worsens once tension is applied.

Best Practices to Prevent Sling Twist

  • Use a Swivel Hook or Eye
    If the load is likely to rotate, use lifting hardware that allows for controlled rotation without affecting the slings.

  • Align Hook with Load COG
    Ensure the hook is positioned directly above the centre of gravity — especially with off-centre or asymmetrical loads.

  • Check for Sling Twists Before the Lift
    Lay slings flat and trace them end to end. Even one 180° twist can compromise performance under tension.

  • Use Equal Sling Lengths
    For multi-leg configurations, confirm sling lengths are even and attachment points are symmetrical.

  • Communicate Before and During Lift
    The lifting crew should agree on the load’s orientation and rotation plan before lifting. Adjust if any twisting occurs mid-lift.

  • Tag Slings with Visual Indicators
    Use coloured tags or stripes along the length of slings to visually detect twists before use.

Special Considerations by Sling Type

  • Chain slings: Less sensitive to twist but still subject to link damage and misalignment.
  • Web slings: Highly vulnerable; twisting weakens structure and causes sharp edge damage.
  • Wire rope: May kink permanently when twisted under load — extremely dangerous.

Real-World Insight

On a fabrication site, a heavy steel tank was lifted using two synthetic slings. One sling was unintentionally twisted once before use. As the crane took the load, the twist forced the tank to rotate slightly, bringing it dangerously close to a scaffolding tower. After that incident, the team implemented a new checklist step: “trace and flatten all slings before every lift.”

Simple precautions prevent serious consequences.

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