ASME p 30.9 Sling Rigging Practices (Transcript Notes)

Scope and Applicability

ASME p 30.9 outlines operating practices for slings and these practices are required anytime a sling is used.
Company context notes some garbled wording in the transcript, but the core ideas are clear: follow the ASME p 30.9 requirements for safe sling use.

Slings: Condition, Use, and General Rules

Damaged or defective slings shall not be used.
Slings shall not be shortened or lengthened by knotting or twisting.
Sling legs shall not be kinked.
The rated load of the sling shall not be exceeded.
Slings used in a basket hitch shall have the loads balanced to prevent slippage.
Slings shall be securely attached to their load.
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9) all employees shall be kept clear of loads about to be lifted and of suspended loads.
10) hands or fingers shall not be placed between the sling and its load while the sling is being tightened around the load.
11) shock loading should be avoided.
12) a sling shall not be pulled from under a load when the load is resting on the sling.
Good load control is the desired result of good practices. Good load control is assured if the load is rigged to the center of gravity.

Center of Gravity and Load Control

The load must lift level and be stable.
Connections must also be securely attached, and the tagline must be used when needed to control load swing and rotation.
Rigging to the center of gravity requires that the main load hook be placed over the center of gravity.
The slings must then be connected securely to the load so that they surround and capture the center of gravity.
Once the weight of the load is known and the center of gravity is located, the slings can be attached to the load.
Load control is affected by the sling hitch selected.
The vertical hitch (connected to the load by a shackle or hook) can provide adequate load control if the load is simple and compact. The connection point must be directly above the center of gravity.
The single leg basket hitch provides adequate load control only on loads that allow the basket to be trapped by the load.
The single wrap basket provides very limited contact with the load.
The single leg choker hitch provides good load control only on simple loads that are relatively short.
The single wrap choker does not provide a full 360-degree contact with the load. Place a block of wood under the choke for more contact with the load.
Two slings connected to the load by hooks or shackles provide excellent load control.
The use of a bridle requires that the sling angle be known to ensure that the slings are not overloaded.

Rigging Configurations and Load Capacity

A double leg basket is formed by connecting two basket hitches to the load. The double basket may have twice the capacity of a bridle at the same sling angle.
A double leg basket must not be used at a sling angle less than 60^ ext{°}.
A double leg choker is formed by connecting two choker hitches to the load. The double choker has 75\% \text{ to } 80\% of the capacity of a bridle at the same sling angle. C{ ext{double leg choker}} = [0.75, 0.80]\times C{ ext{bridle}}.
A double leg choker must not be used at a sling angle less than 60^ ext{°}.
The use of double wrap chokers allows the double leg choker hitch to be used at a horizontal sling angle of 45^ ext{°}. Do not use at a horizontal sling angle smaller than 45^ ext{°}.
Make sure that the double wrap choker does not overlap at the bottom of the load.
Triple and quad leg slings will almost always improve load control if all the legs surround the center of gravity.
The loads on each leg of a three-leg sling or a four-leg sling will rarely be equal. The loads will vary dramatically if the legs are not very closely matched in length and the load is not flexible.
Bridle hitches are variations of the single-leg hitch. They include three- and four-leg slings attached to a common point. The dual leg hitch seen earlier is also a bridle hitch.
The triple-leg bridle hitch has 50\% more capacity than the dual-leg sling, but only if all three legs are the same length and the same distance from the center of gravity. In addition, the legs must be adjusted so that each one carries an equal share of the load.
The quad-leg bridle sling improves load stability, but it often does not provide an increase in lifting capacity. Don't assume that you can take the capacity of one leg and multiply it by the number of legs in the hitch and expect to lift that much weight. With a swinging load, the actual stress on each leg changes constantly.
A variation of the basket hitch is the double basket. This is where two basket hitches are used at two different pick points. Be sure they're far enough apart so that they provide configuration using choker hitches.
Last but not least are the double wrap basket or choker hitches. This is where the sling is wrapped twice around the load. Notice that one of the wraps provides full 360-degree contact, which improves load handling security. This is often a better choice than the standard choker hitch.

Five Final Notes on Rigging

1) Never leave a sling from one connector to another. This changes the angle of loading on the hoist fitting and can double the load on the connector and the load. The correct rigging method here is to use two slings, each attached to the hoist ring and a separate pick point. Note that this may cause the load to buckle if it's not stiff enough to resist the forces of angular loading. In a case like this, test the load by lifting it slowly. If it begins to buckle, you may need to use another method to provide support for the center of the load.
2) Always use padding to prevent wear or chafing or cutting of slings, especially on sharp corners.
3) When a load is to be carried on the deck of an industrial crane, always detach the hook from the load once it's been placed on the deck. If the load should fall off the deck and the hook is still attached, it could kick the crane over. Also, never carry a load on the hook at the same time you have a maximum load on the deck or vice versa. Anything more than maximum would overload the crane.
4) Always pay attention to see that you and any bystanders are standing away from the crane whenever the operator lowers the outriggers. The outriggers come down with hydraulic force that could easily detach parts if not properly guided by hand signals. The work environment is typically noisy, and miscommunication can be dangerous.
5) Use proper hand signals and stay clear of the area during outrigging; miscommunication and high hydraulic forces are common hazards.

Notes on Practicality and Safety Implications

The emphasis across all sections is preventing overload, uneven loading, and uncontrolled load movement.
Center of gravity focus reduces tipping, rotation, and unexpected slippage.
Proper hitch selection depending on load geometry is essential for safe lift and maximizing actual capacity.
Always verify load weight and CG before attaching slings and starting lift, and test the lift with a slow, controlled raise to observe for buckling or unexpected movement.
When in doubt, refer to the rigging handbook or manufacturer guidelines and ensure all personnel are clear before proceeding.