NWSA Rigging and Hoisting Operations 2 — Questions and Answers
Question 1: What is the purpose of a tag line during a tower hoisting operation?
- To identify the load's destination
- To control the load's rotation and lateral movement during lifting and lowering (Correct answer)
- To measure the load's weight
- To provide backup support if the main line breaks
Correct answer: To control the load's rotation and lateral movement during lifting and lowering
Tag lines allow ground personnel to guide and stabilize loads during hoisting, preventing spinning, swinging, and contact with the tower structure.
Tag lines are ropes attached to loads being hoisted to provide directional control. Without them, loads can spin freely, swing in wind, and impact the tower structure. The ground worker must maintain constant tension and never wrap the line around hands or body.
Question 2: What must be done before using a synthetic sling for hoisting on a tower?
- Nothing — synthetic slings are always ready to use
- Inspect for cuts, abrasion, UV degradation, knots, acid damage, and verify the sling is rated for the intended load (Correct answer)
- Only check the color coding
- Synthetic slings don't need inspection because they don't rust
Correct answer: Inspect for cuts, abrasion, UV degradation, knots, acid damage, and verify the sling is rated for the intended load
Synthetic slings degrade from UV exposure, chemicals, heat, and physical damage. Pre-use inspection prevents sling failure.
Inspection per OSHA 1926.251 and ASME B30.9 includes checking for cuts, abrasive wear, UV degradation, chemical damage, knots (which reduce capacity by up to 50%), and heat or burn damage. The capacity tag must be legible. Damaged slings must be cut and discarded.
Question 3: What is the significance of the D/d ratio in rigging operations?
- It measures the distance to the drop zone
- It is the ratio of the diameter of the object the wire rope bends around to the diameter of the rope itself, affecting rope strength and lifespan (Correct answer)
- It determines the number of workers needed
- It calculates the wind speed limit for hoisting
Correct answer: It is the ratio of the diameter of the object the wire rope bends around to the diameter of the rope itself, affecting rope strength and lifespan
When wire rope bends around small-diameter objects, internal stresses increase dramatically, reducing strength and accelerating fatigue failure.
The D/d ratio is critical in wire rope rigging. When this ratio is too small, the rope bends too sharply, causing increased stresses, accelerated fatigue failure, and reduced effective strength. Minimum recommended ratios are typically 20:1 to 30:1 for running sheaves.
Question 4: What determines the safe working load limit for a shackle used in tower rigging?
- Its physical size alone
- The working load limit stamped on the shackle body by the manufacturer, which must never be exceeded (Correct answer)
- The foreman's estimate based on experience
- Shackles have unlimited capacity
Correct answer: The working load limit stamped on the shackle body by the manufacturer, which must never be exceeded
Every rated shackle has a working load limit permanently marked on its body. Exceeding this limit risks catastrophic failure.
Shackles must be rated and marked per ASME B30.26. Side-loading reduces capacity by 50% or more. The pin must be fully seated and secured. Homemade or unmarked shackles must never be used for lifting. Overloaded shackles can fail suddenly and catastrophically.
Question 5: Why is a load calculation required before every hoisting operation on a tower?
- To determine how fast to hoist
- To verify that all rigging components and anchor points can safely support the load with appropriate safety factors (Correct answer)
- Load calculations are only needed for loads over 5,000 pounds
- To calculate the electricity cost of running the hoist
Correct answer: To verify that all rigging components and anchor points can safely support the load with appropriate safety factors
Without accurate load calculations, rigging components could be overloaded, causing equipment failure and potentially fatal injuries.
Load calculations include total load weight plus rigging hardware, applying safety factors (typically 5:1), verifying every component in the system is rated above the calculated load, accounting for sling angle factor, and considering wind forces on large panels.
Question 6: What hand signals are used for hoisting operations when radio communication fails?
- There are no standard hand signals for rigging
- Standardized hand signals as defined in ASME B30.5 including fist rotation for hoist, open palm for stop, and arm pointing for direction (Correct answer)
- Any random gesture works as long as the crew agrees
- Hand signals are not reliable enough to use
Correct answer: Standardized hand signals as defined in ASME B30.5 including fist rotation for hoist, open palm for stop, and arm pointing for direction
ASME B30.5 standardized hand signals ensure clear communication for critical lift operations.
ASME B30.5 and OSHA 1926.1419-1422 define standardized signals: HOIST (circular motion with finger up), LOWER (circular with finger down), STOP (arm horizontal, palm down), EMERGENCY STOP (both arms swung horizontally). Only one designated signal person gives signals.
NWSA Rigging and Hoisting Operations 2
What is the purpose of a tag line during a tower hoisting operation?