Frequently Asked Questions

Rigging, Slinging and Lifting

What is the rule of thumb formula used to calculate the WLL of a flexible steel wire rope?

If the Working Load Limit (WLL) of the flexible wire rope is unknown, the rule of thumb formula to compute the WLL is: Diameter in mm squared x 8 = WLL in kg.

Example:

  • The WLL of a 15 mm wire rope = 152 x 8 = 15 x 15 x 8 = 1800 kg
  • The WLL of a 20 mm wire rope = 202 x 8 = 20 x 20 x 8 = 3200 kg.
  • The WLL of a 25 mm wire rope = 252 x 8 = 25 x 25 x 8 = 5000 kg.

What is the rule of thumb for determining the working load limit (WLL) of synthetic rope?

If the WLL of a synthetic fibre rope is unknown, the formula for determining the WLL is: Diameter in mm squared = the WLL in kg.

Example:

  • The WLL of a 12 mm fibre rope is: 122 = 12 x 12 = 144 kg.
  • The WLL of a 15 mm fiber rope is: 152 = 15 x 15 = 225 kg.
  • The WLL of a 20 mm fiber rope is: 202 = 20 x 20 = 400 kg.

What are the requirements for safe storage of synthetic webbing slings?

  • Store in a clean, dry and well ventilated place.
  • Never store on the ground or floor.
  • Store out of direct sunlight, ultraviolet light or fluorescent lighting.
  • Store away from chemicals.
  • Store away from oils.
  • Store away from sand/grit.
  • Store away from machinery.
  • Store in a vermin free environment.

When should a synthetic web sling be discarded?

Synthetic webbing slings must be removed from service when any of the following substandard conditions exitst:

  • Label or tag has been removed and/or destroyed or not legible.
  • Knots, snags, holes, tears or cuts.
  • Damage to sleeve.
  • Evidence of external wear or excessive abrasions.
  • Evidence of internal wear.
  • Melting or charring of any part of the sling surface.
  • Any signs of damage by temperatures, sunlight or chemicals.
  • Damage to the eyes, corrosion discoloration or other damage to end fittings or terminal attachments.
  • Signs of contact with acids for nylon slings or signs of contact with organic solvents for polyster slings.
  • Broken or worn stitches. 

When should lifting hooks be discarded and removed from service?

Lifting hooks must be discarded and removed from service if any of the following unsafe conditions are observed during the regular and pre-use inspection:

  • Missing or illegible manufacturer identification.
  • Any cracks, nicks and gouges.
  • Damage from heat.
  • Any unauthorized repair done on the hook.
  • Any twist from the plane of the unbent hook.
  • Improper operation and locking of self-locking hook.
  • Any wear exceeding 10% of the original dimension.
  • An increase of the throat opening by 5% due to wear or distortion.

When should shackles be discarded and removed from service?

Shackles must be discarded and removed from service immediately if the following unsafe conditions are observed during regular or pre-use inspection:

  • Excessive pitting or corrosion.
  • A 10% or more reduction from the original dimension at any point around the body or pin.
  • Damage on the shackle body including: bent, twisted, distorted, stretched, elongated, cracked, or broken load-bearing
    components.
  • Excessive nicks or gouges.
  • Indication of heat damage (weld splatter, arc strike, etc.)
  • Incomplete pin engagement.
  • Excessive thread damage.
  • Evidence of unathorized repair or welding.

The Golden Rule of Lifting

Lifts utilizing cranes, hoists, or other mechanical lifting devices will not commence unless:

    • An assessment of the lift has been completed and the lift method and equipment have been determined by ancompetent person(s);
    • Operators of powered lifting devices are trained and certified for that equipment;
    • Rigging of the load is carried out by a competent person(s);
    • Lifting devices and equipment have been certified for use within the last 12 months (at a minimum);
    • Load does not exceed dynamic and/or static capacities of the lifting equipment;
    • Any safety devices installed on lifting equipment are operational.;
    • All lifting devices and equipment have been visually examined before each lift by a competent person(s).

    Fibre Rope Inspection

    During fibre rope inspection, condemn the fibre rope from safe use for lifting purposes if any of the following is observed during inspection:

    • Strands are fraying
    • Strands are cut
    • Rope rotted by acid or alkali
    • Rope affected by heat or sun
    • Rope affected by molds
    • Rope has been overloaded
    • Rope chafed inside or outside
    • Unlaid stands
    • Knotted rope