The term “rigging” originated as a nautical word defined as the ropes, chains, and other lines that support the mast and spars of a vessel or serves to set and trim the sails.
Today, rigging is the process of moving heavy loads with slings, hoists, and other equipment. In much the same way rigging had to be correctly set for a ship to arrive at its designated port, proper planning is essential to ensure a rigging job moves the load safely and securely from start to finish.
Three factors come into play in every rigging job:
- The weight of the object
- The center of gravity of the object
- The path to be taken
Only after the rigger knows these factors can he choose the best rigging and lifting techniques for moving the object in the safest manner possible.
Lacking proper planning and the necessary precautions, a rigging operation could result in incidents such as tip-overs, boom failure, or contact with overhead power lines. In addition, improper rigging or rigging failure could expose riggers, crane or hoist operators, and other nearby workers to potential hazards.
7 Rigging Rules
The three factors listed above are only the beginning. Industrial Training International (ITI), an education and training provider for those who use cranes, rigging and load handling equipment, recommends following these seven rigging rules:
- Know the load weight or perform your best estimate.
- Locate or estimate the location of the load’s Center of Gravity (CG).
- Determine the load-share on each side of CG.
- Calculate the tension in each sling leg.
- As a minimum, select slings with capacity to match the sling-leg tension and hardware to match the vertical capacity of the slings.
- Inspect the rigging per ASME B30.9 and 29 CFR 1910.184.
- Ensure load control. Make sure the hitch or hitches, and their edge protection, provide good to excellent control, so slipping does not occur.
Ask the Right Questions
Proper planning and precaution involves asking the right questions, such as:
- Is the equipment in acceptable working condition?
- Has it been properly inspected?
- Is it the right rigging for the job?
- What is the sling angle?
- Will side loading be necessary?
- Will the load be under control?
- Are there any unusual loading or environmental conditions such as wind, temperature, or unstable surfaces?
Basic Sling Operating Practices
Lastly, it is essential that you take the proper precautions when using slings. The U.S. Department of the Interior prescribes the following guidelines:
- Inspect the slings, fastenings and attachments for damage and defects.
- Replace slings that show abrasion, scraping, or which show evidence of heat damage.
- Do not shorten slings with knots, bolts, or other makeshift devices, or kink sling legs.
- Balance sling loads used in a basket hitch to prevent slippage.
- Securely attach slings to their loads.
- Do not load slings in excess of their rated capacity.
- Pad or protect slings from the sharp edges of their loads.
- Keep suspended loads clear of all obstructions.
- Keep all employees clear of loads about to be lifted and of suspended loads.
- Do not pull a sling from under a load when the load is resting on the sling.
- Do not place hands or fingers between the sling and its load while the sling is being tightened around the load.
- Do not drag slings on the floor or over an abrasive surface.
Taking the time to “trim the sails” with proper planning and precautions when conducting a rigging operation will help to ensure that the load is moved safely and without incident to equipment or workers.