IST Rigging, Hoisting and Material Handling

Question 1

A 2,000 lb load is lifted with a two-leg bridle sling. Each leg is at 60° from horizontal. About how much tension is on each leg?

Accepted Answer

1,155 lb

Answer

Each leg carries half the load (1,000 lb) times the sling angle factor. At 60°, that factor is 1/sin(60°) ≈ 1.155, so each leg carries about 1,155 lb. Leg tension rises as the angle gets flatter.

Question 2

Why should sling angles below 30° from horizontal generally be avoided?

Accepted Answer

Leg tension rises sharply and can exceed the sling's rated capacity

Answer

As a sling angle flattens, the tension in each leg climbs quickly. At 30°, each leg carries the full load weight, and below that it carries even more. This makes overload very likely.

Question 3

Compared with a vertical hitch, roughly what share of the vertical rated capacity does a sling typically have in a choker hitch?

Accepted Answer

75%

Answer

The choke point bends and stresses the sling, so a choker hitch is commonly rated at about 75% of the vertical capacity at standard choke angles. A basket hitch, by contrast, can be rated up to 200%.

Question 4

Which wire rope condition requires removing the rope from service?

Accepted Answer

Birdcaging or kinking

Answer

Birdcaging (strands spreading apart) and kinking are permanent structural damage that greatly reduce the rope's strength. Either one means the rope must be removed from service.

Question 5

What is the main purpose of a tag line during a lift?

Accepted Answer

To control rotation and swing of the load from a safe distance

Answer

A tag line is a rope attached to the load. It lets a worker guide the load and stop it from spinning or swinging, without standing under it or touching it directly.

IST - Industrial Skills Test Practice Test

IST - Industrial Skills Test Practice Test

IST Rigging, Hoisting and Material Handling