WORKING LOAD LIMITS OF SLINGS

Observing the WLL is a critical safety aspect in all overhead lifting operations. Exceeding the WLL of a chain sling can cause chain failure and, consequently serious injury. To avoid hazards, consider:

  • Always accurately determine the load, force, or weight that is to be lifted or carried with the chain sling.
  • Do not attempt to use a chain sling without complete and accurate knowledge of the force or weight carried by each part of the sling. Even if the sling as a whole may be within the WLL, non-uniform center of gravity locations can result in unbalanced loading conditions.
  • Include all applicable capacity reduction factors when determining the WLL. These factors can substantially reduce the ability of the chain sling to carry a load safely.
  • Do not use slings at angles of less than 30 degrees, as measured from the horizontal plane.
  • Chemically active environments can reduce the strength and WLL of an alloy steel chain sling, or even make the sling unusable.
  • Shock or impact loading can substantially increase the chain sling's force to a level well beyond the WLL.
  • Consult an engineer for approval prior to performing a lifting application if the load's weight or chain sling's WLL is unknown.


  • INSPECTION AND MAINTENANCE

    In order to ensure a safe operation of chain slings, inspection and maintenance are very important. Excessive wear of any single component can result in a failure of the sling and serious injury.

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    Proper safety practices should be followed, including never walking under a suspended load.

    Credit: Pewag

    In order to avoid this hazard, keep the following points in mind:

  • Inspect slings in accordance with federal OSHAregulations and ASME B30.9 standards
  • Perform and record frequent and periodic inspections of chain slings
  • Prior to use, order an inspection of all new, altered, modified, or repaired chain slings to verify compliance with ASME B30.9
  • Visually inspect chain slings for damage before use each day
  • Proper measurements using precision instruments of each link and each component should be performed to provide a benchmark for allowable tolerances
  • Written records containing the most recent periodic inspection should be maintained by the owner or user of the chain sling.
  • — Michael W. Uhrenbacher is the general manager of Pewag Inc., Burr Ridge, Ill.

    Safety checklist
  • Ensure all slings have identification and warning tags
  • Maintain records, including test certifications, drawings, instructions, warnings, and maintenance records of each chain sling
  • Ensure that personnel performing overhead lifting applications are properly trained
  • Ensure that slings are inspected before use
  • Establish an inspection and maintenance plan in accordance with ASME
  • Perform sizing and load calculations to ensure loads remain within working load limits
  • Review and approve lifting applications to ensure loads remain within working load limits and that lifts remain stable
  • Familiarize yourself with federal OSHA requirements and ASME B30.9 standards.
  • Choosing the right chain
  • Determine the maximum load to be lifted
  • Determine the type of slings needed (single, double, etc.)
  • Estimate the proper angle between the leg of the sling and the load
  • Select the proper fittings (hooks, master rings, etc.)
  • Determine the overall reach (measured from the bearing point on the master link to bearing point of fitting)
  • Choose a chain size that meets your required work load, angles, and reduction factor
  • Choose1222222 grade, type, and finish of steel that meets your requirements.