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Sling and Hoist Selection Guide

Document Number: 104

Introduction

Slings and hoists are tools used in many industries for moving large heavy loads in the workplace. Slings and hoists are available in hundreds, if not thousands, of options and styles. This tremendous selection can make the job of choosing the correct sling or hoist very challenging. The wrong choice has led to thousands of accidents and even deaths each year in the United States. This document is a basic guide to help the individual in charge of rigging select the correct sling or hoist for a job. It also addresses basic rigging applications. Other applications not addressed here should always be referred to an expert.

Hoist Selection

Before a hoist can be selected, careful consideration should be given to duty cycle, lift, headroom, atmosphere, speeds, distance, efficiency, safety, and economy. The best way to select the proper hoist is to consider the working conditions the hoist will be subjected to and the type of application it will be required to perform. The primary concern will be the capacity required for the load to be lifted. Not only must you consider the largest load you intend to handle, but you must include the weight of any hook lifting devices such as spreader bars, grabs, slings, etc. Hoists are typically used in combination with other equipment, i.e. trolleys and boom cranes. It is important to remember to check this ancillary equipment as well as the hoist. Both devices should have an engineer verify that they will tolerate the stress applied to them. Despite the fact that most hoists do have a safety factor allowance, never exceed the rated capacity stamped on the hoist for any reason. Exceeding the rated capacity, even for a short period, will cause equipment damage and can result in serious injury.

Sling Selection

Slings are used in combination with a lifting device. The most common lifting devices are overhead cranes, hoists, and forklifts. To select the correct sling, two questions must be answered: what type of sling and what size (diameter or thickness)?

The four main types of slings and their applications are:
1. Chain	Combines superior strength, east of handling and durability. The combination of heavy loads, elevated working temperatures and severe lift conditions usually dictate that an alloy chain sling be used. Typically used in steel mills, foundries, and heavy machining operations that require repetitive lifts.
2. Wire Rope:	The most commonly used sling. It also has the lowest cost per ton of lift. Used in the construction industry and other industries where heavy loads and rugged conditions exist.
3. Mesh:	Wire and Chain. Excellent in lifting objects that are hot or have sharp edges, such as bar stock or plate steel. Mesh slings usually have wide load bearing surfaces that greatly enhance load balancing. Machine shops and steel warehouses typically have applications requiring mesh slings.
4. Synthetic	Both web and roundslings are used where loads must be protected from damage. The light weight and flexibility reduce fatigue and strain on the rigger.

The size of the sling is determined by the weight, shape, and size of the load. When determining the stress that will be applied to a sling, the length of the sling is divided by the vertical distance from the top of the load to the lifting device. The resulting quotient is multiplied by the shared weight of the load.

Tension in "c" = length "c" divided by length "a" multiplied by share of load wt.
"c"/"a" = Load Factor

Given: length "c" = 10' and length "a" = 8', what is tension in "c"?

Solution: Tension in "c" = 10/8 x 5,000, Tc = 1.25 x 5,000, Tc = 6,250#

Once the stress is determined, use the Rigger's Reference Charts (Figures 2 and 3) to determine the diameter necessary to safely lift the load.

Figure 2 - Sling Capacities

MECHANICAL SPLICE IN POUNDS ---- DESIGN FACTOR - 5:1 Wire Rope IPS IWRC
Size in inches	VERTICAL	CHOKER	2-LEGS OR BASKET 90°	60°	45°	30°	Color Code (Optional)	Size in inches
1/4	1,100	840	2,200	1,940	1,580	1,100	White	1/4
5/16	1,700	1,300	3,400	3,000	2,400	1,700	Lt. Green	5/16
3/8	2,400	1,860	4,800	4,200	3,600	2,400	Red	3/8
7/16	3,400	2,500	6,800	5,800	4,800	3,400	Yellow	7/16
1/2	4,400	3,200	8,800	7,600	6,200	4,400	Lt. Blue	1/2
9/16	5,500	4,200	11,000	9,600	7,700	5,500	Black	9/16
5/8	6,800	5,000	13,600	11,800	9,600	6,800	Orange	5/8
3/4	9,700	7,200	19,400	16,800	13,600	9,700	Tan	3/4
7/8	13,000	9,800	26,000	22,000	18,300	13,000	Dk. Green	7/8
1	17,000	12,800	34,000	30,000	24,000	17,000	Purple	1
1-1/8	20,000	15,600	40,000	36,000	30,000	20,000	Dk. Blue	1-1/8
1-1/4	25,000	18,400	50,000	42,000	34,000	25,000	Gold	1-1/4
		Multiplier --->		1.00	.75	.60	<--- Multiplier

Formula to find sling length ---> Load width x Multiplier = Sling Length

Figure 3 - Sling Capacities

	Size in inches	VERTICAL	CHOKER	2-LEGS OR BASKET 90°	60 degrees	45 degrees	30 degrees	Color Code (Optional)	Size in inches
Chain G-8	9/32 3/8 1/2 5/8	3,500 7,100 12,000 18,100	2,620 5,300 9,000 13,500	7,000 14,200 24,000 36,200	6,050 12,300 20,800 31,300	4,950 10,000 17,000 25,600	3,500 7,100 12,000 18,100	Must be tagged for length & strength	9/32 3/8 1/2 5/8
Web	1-9-1 1-9-2 1-9-3 1-9-4 2-9-3 2-9-4	1,600 3,200 4,800 6,400 8,880 11,520	1,280 2,560 3,840 5,120 7,100 9,210	3,200 6,400 9,600 12,800 17,760 23,040	2,770 5,540 8,320 11,090 15,390 19,960	2,260 4,452 6,780 9,040 12,540 16,270	1,600 3,200 4,800 6,400 8,880 11,520	Must be tagged for type, length & strength	1-9-1 1-9-2 1-9-3 1-9-4 2-9-3 2-9-4
Polypro Rope	1/2 9/16 5/8 3/4 7/8 1	645 780 950 1,300 1,760 2,140	325 390 475 650 880 1,070	1,290 1,560 1,900 2,600 3,520 4,280	1,120 1,350 1,650 2,250 3,050 3,700	910 1,100 1,340 1,840 2,490 3,030	645 780 950 1,300 1,760 2,140	Should be tagged for length & strength	1/2 9/16 5/8 3/4 7/8 1

Terminology

Lubrication free load brake - low friction materials are used in the brake mechanism so lubrication is not necessary.

10' lift hoist or 20' lift hoist - This is the maximum lifting height for a load.

The term 1' overhaul lift/ft. means the hoist uses a loop of chain in the lifting mechanism. If a hoist has a rating of 30 for the 1' overhaul lift/ft., then 30' of chain would need to move in order to raise an object 1'. To raise an object 2', 60' of chain would need to be moved.

Regulation

OSHA regulates slings in 29 CFR 1910.184. The regulation covers general requirements, basic definitions, safe operating practices, inspections of the various types of slings. OSHA regulates hoists in 29 CFR 1910.179.

Commonly Asked Questions

Q.	*What does angle factor mean in rigging?*
A.	Angle factor deals with the stress the sling is subjected to at different slinging angles. As the angle increases (degree number gets smaller) the stress applied to the sling increases, which results in a decrease in capacity of the sling, i.e. A thirty degree sling angle would result in a 50% reduction in the sling capacity.
Q.	*How do I get more life out a synthetic sling?*
A.	Use a wear-pad, either sliding or sewn-on.
Q.	*Can you tie knots in a sling?*
A.	No, it will reduce the lifting capacity by a minimum of 50%.

References

M. Brett, Phone interview, 24 June 1998.

Accident Prevention Manual for Industrial Operations, Engineering and Technology, ninth edition.

American National Standards Institute, 1430 Broadway, New York, N.Y. 10018. "Safety code for Cableways, Cranes, Derricks, Hoists, Hooks, Jacks, and Slings," B30 Series

29 CFR 1910.179

29 CFR 1910.184

AISI Wire Rope Users Manual, 2nd editions.

Wire Rope & Rigging Consultants, 1992 edition.

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Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.