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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.
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