NCCCO Rigger flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Sling inspection frequency

Rigging slings must be inspected before each use and at least annually by a qualified person; periodic inspections are documented and defective slings are removed from service immediately.

Wire rope broken wire limit

A wire rope sling is removed from service when there are ten randomly distributed broken wires in one lay, or five broken wires in one strand in one lay.

Chain sling wear limit

A chain sling is removed from service when link wear exceeds ten percent of the original link diameter, or when cracks, gouges, or stretch are found.

Web sling removal criteria

Synthetic web slings are removed for holes, cuts, tears, snags, severe abrasion, broken stitching, chemical damage, or missing or illegible identification tags.

Missing sling identification tag

A sling without a legible tag showing capacity, length, and manufacturer is removed from service because its working load limit cannot be verified.

Hook throat opening limit

A hook is removed from service when the throat opening has increased more than fifteen percent or the hook is twisted more than ten degrees from its original plane.

Shackle inspection points

Inspect shackles for cracks, bent pins, worn threads, and wear exceeding ten percent of the pin or body dimension; discard any shackle with these defects.

Frequent versus periodic inspection

Frequent inspection occurs before each shift or use, while periodic inspection is performed at least annually and documented by a qualified person, with records retained.

Vertical hitch capacity

A single vertical sling leg is rated at its full working load limit, and the load is shared equally only when multiple legs are symmetrical and the center of gravity is centered.

Choker hitch capacity

A choker hitch typically reduces sling capacity to about seventy-five to eighty percent of the vertical rating, depending on sling type and manufacturer.

Basket hitch capacity

A basket hitch with two vertical legs can support twice the single-leg working load limit when the load is balanced and both legs carry equal tension.

Sling angle tension formula

For a symmetrical two-leg lift, tension per leg equals load divided by two times the sine of the angle each leg makes with horizontal.

Sling angle effect

As sling legs move closer to horizontal, tension increases sharply; at thirty degrees from horizontal each leg carries the full load in a two-leg lift.

Bowline knot strength

A bowline forms a fixed loop and retains roughly sixty to seventy percent of rope strength, but knotted slings are not permitted for overhead lifting.

Choker hitch application

A choker hitch wraps around the load and passes the sling through its own eye, tightening under load; it is used where the load could slip out of a basket.

D/d ratio effect

Small D/d ratios, the diameter of curvature divided by sling diameter, reduce basket and choker capacity; ratings assume adequate curvature, commonly about 25:1.

Minimum approach distance

Keep cranes, rigging, and loads at the OSHA minimum approach distance from energized power lines; the required distance increases with line voltage and must be verified before work.

Center of gravity below hook

The load's center of gravity should be below the lifting point; otherwise the load may tilt or flip, causing shock loading and loss of control.

Shock loading hazard

Sudden starts, stops, or jerks multiply the load on rigging far above its static weight, so lifts must be smooth and controlled.

Sharp edge protection

Sharp corners cut wire rope and synthetic slings; use edge protectors, softeners, or padding, and never drag a sling across a sharp edge.

Personnel under suspended load

Workers must never stand or pass beneath a suspended load; barricade the area and use tag lines to keep personnel clear of the drop zone.

Synthetic sling heat damage

Synthetic web slings lose strength when exposed to heat, chemicals, or ultraviolet light; inspect for discoloration, stiffness, or melting and remove damaged slings.

Side loading hazard

Rigging components such as shackles and hooks are rated for axial loading; side loading can bend or open them and must be avoided or derated per manufacturer.

Ground stability hazard

Soft or uneven ground can cause outriggers or lifting equipment to settle, so ground bearing capacity must be assessed and mats used when needed.

Hook load in saddle

Load the hook in the saddle, the lowest point of the hook bowl, never on the tip, and keep the hook latch closed during the lift.

Shackle pin orientation

Install the shackle pin so the load does not roll the pin loose; fully seat the pin and never replace it with a bolt of lower strength.

Shoulder eyebolt loading

Shoulder eyebolts must be seated flush and loaded in line with the bolt axis; angular loading reduces capacity unless the eyebolt is specifically rated for it.

Spreader beam use

A spreader beam keeps sling legs vertical on a wide load, reducing compressive force on the load and avoiding sling angle capacity loss.

Tag line purpose

A tag line controls rotation and swing of a suspended load from a safe distance; it is never used to lift or to pull a load outside the crane's rating.

Web sling application

Synthetic web slings are suited to polished, finished, or delicate loads because they are soft and non-marring, but they are not for hot or sharp loads.

Chain sling application

Chain slings resist abrasion, cutting, and high temperatures, making them suitable for rough castings and structural steel, but they must be inspected for stretched links.

Two-leg bridle hitch

A two-leg bridle hitch attaches two sling legs to a common lifting point; capacity depends on the angle between legs and the load's center of gravity.