NCCCO Rigger Level I flashcards

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

Periodic inspection interval

Rigging must receive a documented periodic inspection at least every 12 months, in addition to inspection before each use and at the start of each shift.

Wire rope broken wire rule

Remove a wire rope sling from service when 12 randomly distributed broken wires occur in one lay, or 4 broken wires in one strand in one lay.

Chain sling stretch limit

A chain sling is removed from service when any link has stretched more than 5 percent of its original length or shows cracks, nicks, or gouges.

Web sling rejection signs

Cuts, snags, holes, burns, ultraviolet degradation, broken stitching, or a missing load tag require removal of a synthetic web sling from service.

Hook throat opening rule

A hook is removed from service when its throat opening has increased more than 5 percent or wear exceeds 10 percent of the original dimension.

Shackle inspection criteria

Reject a shackle showing cracks, a bent pin, a distorted bow, or threads that will not fully engage; the pin must be the correct type and fully seated.

Sling ID tag requirement

Every sling must carry a legible tag showing its rated capacity and identification; a missing or unreadable tag means the sling is out of service.

Round sling core damage

A synthetic round sling is removed from service when the cover is damaged enough to expose the core or when core yarns are broken.

Vertical hitch capacity

A vertical hitch carries the full single-leg rated capacity of the sling, with the load hanging directly below the hook.

Choker hitch capacity

A choker hitch reduces sling capacity to roughly 75 to 80 percent of the vertical rating because the sling bends back on itself.

Basket hitch capacity

A basket hitch with both legs vertical can reach up to 200 percent of the single-leg vertical rating, but capacity drops as legs angle outward.

Sling tension formula

Leg tension equals load weight multiplied by the load factor, divided by the number of legs; the load factor rises as the horizontal angle decreases.

Sling angle factor

The tension multiplier is about 1.155 at 60 degrees from horizontal, 1.414 at 45 degrees, and 2.0 at 30 degrees.

D/d ratio effect

Capacity of a wire rope sling in basket or choker hitch decreases as the ratio of bend diameter to rope diameter falls below 25.

Bridle hitch angle limit

In a bridle hitch, the included angle between legs should not exceed 90 degrees; wider angles sharply increase leg tension and reduce capacity.

Bowline strength retention

A bowline knot retains roughly 60 to 70 percent of the rope's strength; knots generally reduce rope strength by 40 to 60 percent.

Knots in wire rope

Knots must never be tied in wire rope or chain slings; knots are only appropriate in fiber rope where reduced capacity is accounted for.

Shock loading hazard

Sudden application of load, such as jerking or dropping, can multiply forces several times over static weight and overload the rigging.

Center of gravity rule

The hook must be positioned directly above the load's center of gravity, or the load will tilt and shift when lifted.

Low sling angle risk

As the horizontal angle falls below 45 degrees, leg tension rises sharply and horizontal force on the load increases, risking sling failure.

Suspended load rule

Never stand or pass any body part under a suspended load; keep hands and feet clear of pinch points, hook throats, and contact points.

Electrical approach hazard

Maintain the required minimum approach distance from energized lines; wet conditions and conductive rigging increase the risk of electrocution.

Environmental load hazards

Wind, ice, rain, and heat affect load stability and rigging capacity; tag lines control rotation and swing during lifting.

Sharp edge protection

Sharp corners cut slings; use softeners, corner protectors, or edge rollers to prevent abrasion and cutting of the sling body.

Primary rigging failure causes

Overloading, worn or damaged gear, improper hitch selection, edge contact, and load shift are the leading causes of rigging accidents.

Chain sling grade rule

Only grade 80 or grade 100 chain is used for overhead lifting; proof coil and transport chain must never be used as slings.

Web sling limitations

Synthetic web slings are lightweight and non-marring but vulnerable to cuts, ultraviolet light, chemicals, and heat, so protect them from sharp edges.

Shackle pin selection

Use a screw pin shackle for temporary or repeated connections and a bolt-type shackle for permanent or long-term connections.

Hook loading rule

Never tip-load a hook; the load must seat in the bowl of the hook, and the hook must have a functioning latch or be moused.

Spreader beam function

A spreader beam converts the lifting force into compression and bending in the beam, keeping sling legs vertical and reducing load on the pick points.

Equalizer beam function

An equalizer beam distributes load between pick points without imposing a bending moment, useful when pick points are not equidistant from the center of gravity.

Tag line purpose

A tag line controls load rotation and swing; keep personnel clear of the load path and never wrap a tag line around a body part.