Intermediate Rigging (RI) common mistakes
Intermediate Rigging (RI) · Understand the traps and how to avoid them.
Treating the sling's vertical or single-leg capacity as the capacity for a multi-leg hitch, or adding leg capacities arithmetically instead of applying the hitch angle factor (sin of the angle from horizontal).
Candidates memorize one capacity number per sling and never convert it for basket, choker, or bridle configurations, so they assume a two-leg sling lifts twice the single-leg load regardless of angle.
What to do instead
Practice computing vertical, choker, and basket capacities for each sling type, then apply the angle multiplier for every leg and verify the tension in each leg, not just the total load.
Selecting a sling by weight alone while ignoring the load's shape, center of gravity, sharp edges, and the resulting tendency to shift or rotate during the lift.
Exam items present a weight and a sling capacity and candidates stop calculating once the numbers match, overlooking geometry and edge protection that determine whether the hitch is stable.
What to do instead
For every sling-selection item, list the load's weight, CoG location, contact edges, and hitch type before comparing capacities, and add edge protection or a different hitch whenever the geometry demands it.
Rejecting or accepting sling and hardware condition based on a single obvious defect, missing removal criteria such as broken wires in a specific lay length, heat damage, stretch, or distorted or cracked hardware.
Candidates look for the dramatic defect (a cut, a bent hook) and skip the systematic checklist, so they miss cumulative damage that is the actual removal criterion.
What to do instead
Work a fixed inspection sequence for every item: identify the tag, check for broken wires or core exposure, look for heat or chemical damage, measure wear and distortion against limits, and confirm latch function on hooks.
Using a rigging hook or shackle in a way that side-loads it, loads the hook tip, or exceeds the reduced capacity from a non-axial pull, without recognizing the derating.
Candidates see a rated capacity stamped on the hardware and assume it applies in every orientation, forgetting that hooks and some shackle configurations lose capacity off-axis.
What to do instead
Confirm the load line passes through the saddle or bowl and along the hardware's designed axis, and when the geometry forces an off-axis pull, apply the reduced capacity or substitute properly rated hardware.
Reading the crane load chart at the wrong radius or boom length, or using the main boom chart for a jib or auxiliary configuration.
Candidates take the radius from the boom pivot or the load's position rather than the crane's center of rotation, and they grab the first chart in the book without matching the boom and jib setup.
What to do instead
Always measure radius from the center of rotation to the hoist line at the load, confirm the boom length and configuration against the chart heading, and interpolate only between the chart's own values.
Omitting deductions from gross capacity, such as the weight of the hook block, slings, spreader beam, and any attached rigging, or forgetting to add the load's dynamic and wind effects.
Candidates compare the net load weight directly to the chart's gross capacity, treating the chart value as available payload rather than the total suspended weight the crane must support.
What to do instead
Build a lift-weight worksheet that sums the load, all rigging, and the hook block, then subtract that total from the chart capacity and apply any required margin before declaring the lift acceptable.
Planning a lift without accounting for ground bearing pressure, outrigger setup, level, and overhead or swing-path obstructions, treating the lift plan as a pure capacity calculation.
Candidates focus on the load chart because it is quantifiable and skip site conditions that are qualitative but equally decisive, especially on soft or sloped ground.
What to do instead
Include a site-condition section in every lift plan covering outrigger mats and bearing area, ground slope, underground voids, swing radius, power lines, and the escape path for personnel.
Using hand signals that are approximate or non-standard, or continuing a lift when the signaler is out of the operator's view or communication is ambiguous.
Candidates learn signals loosely and assume the operator can infer intent, and they hesitate to stop a lift because stopping feels like admitting error.
What to do instead
Drill the standard signal set to exactness, establish one designated signaler with a backup, and treat any loss of signal or line of sight as an automatic stop until communication is restored.
Standing inside the swing radius or under the suspended load while guiding it by hand, or riding the load or hook.
Candidates focus on controlling the load's position and forget that their own body is inside the crush and pinch zone, especially when tag lines are absent or ineffective.
What to do instead
Use tag lines from outside the swing radius, keep hands off the load once it is tensioned, and enforce a hard rule that no part of the body passes under or inside the path of the load.
Skipping or rushing the pre-lift check: not verifying the load's actual weight against the documented weight, not confirming rigging attachment points, and not doing a trial lift.
Candidates treat the pre-lift as paperwork and trust the stated weight, so an unverified or misjudged weight or a marginal attachment point surfaces only after the load is airborne.
What to do instead
Run a documented pre-lift: verify weight from a reliable source, inspect and confirm each attachment point, tension the rigging and check for load shift, then perform a controlled trial lift before the full lift.