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GEN
ERAL
INFO
. AND
TRAININGLift Planning and Evaluation
Before using any rigging device it is important to plan your
work and work your plan. The front end time required to develop a
successful lift plan may seem unnecessary for small or
non-consequential loads. Theres always enough time to pre-plan
critical lifts. After an incident involving what seemed to be a
non-consequential amount of weight, the time required to mitigate
the mess will dwarf the time spent on what was thought to be an
unnecessary lift planning session. Theres always enough time to do
the job right, the second time. We encourage you to make the front
end investment in lift planning and successful rigging, before each
and every lift.
A trained, qualified and knowledgeable user must take into
account the following factors and issues and consider all relevant
factors not addressed. Among the factors related specifically to
slings and rigging, users must perform several activities,
including (but not limited to) the following items:
Fee based engineering services, including analysis and
consideration of the above variables is available.Please contact us
for details.
ENGINEERING SERVICES
Single or Multiple Crane/HoistsMaximum/Planned Operating
RadiusAllowable Load (From Load Chart)Ratio of Lift to Allowable
LoadClearance between Boom and LiftClearance to Surrounding
FacilitiesPower Lines and Environmental HazardsEnsure a Clear Load
PathEmergency/Contingency Set Down AreaThorough Equipment
Inspection
Sling selection: Type and CapacityLoad ControlLift Point over
the CGAppropriate Hitch for CG and Load ControlCoordination of
Multiple Slings Positive Sling to Load EngagementCoefficient of
Friction: Sling to LoadLoad is Free to Move and is not SnaggedSling
Capacity is Adequate (Angle and Tension)Adequate Sling
Protection
EQUIPMENT AND LIFT CRITERIA RIGGING CONSIDERATIONS
WindWeatherVisibilityObject TemperatureEnvironmental
TemperatureChemical Conditions and Exposure Stability of the
GroundUnderground Installations
WeightDimensionsCenter of Gravity (CG)Attachment Point
IntegrityStructural Stability: Bend and FlexSusceptibility to
Crushing or CompressionLoose Parts that could fall from the
LoadCombination Loads-Drain FluidsDamaging Surfaces and/or
Edges
ENVIRONMENTAL CONSIDERATIONS LOAD CONSIDERATIONS
PERSONNEL CONSIDERATIONS
Area Clear of Unnecessary PersonnelPersonnel are Trained and
QualifiedPre-Lift Plan and Meeting
Signals: Visual, Audible, Electronic, etc.Tag Lines and Spotter
RequirementsPersonnel Away from Load and Other Dangers
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Purchase and Use Considerations
RIGGING FACTORS
TRAINING
SLING PROTECTION
SLING SELECTION Prior to selection, read and understand the
information contained in our catalog and your responsibilities as
detailed in all applicable regulations and standards. Select the
sling with suitable characteristics for the load, environment and
configuration of lift.
LOAD WEIGHT: Is the weight of the load within the Work Load
Limit of the sling(s)?
WEIGHT DISTRIBUTION: Uneven load weight distribution imposes
disproportionate loading on the individual sling legs.
ADEQUATE SLING LENGTH: Slings must be long enough to ensure the
Work Load Limit is adequate, when the sling-to-load angle is taken
into account. Inadequate consideration has caused under-rated
slings to fail.
LOAD CONTROL: The sling user is responsible for load control.
Slings must be rigged in a manner that provides for control of the
load. Balancing and supporting the load, from the sides above the
center of gravity is critical. Use more than one sling to balance
the load so it will not tilt when lifted.
CENTER OF GRAVITY: The lifting mechanism must be positioned
directly over the center of gravity, before the load is lifted. If
this is not done, the load will change out and the center of
gravity will end up under the lifting fixture. The center of
gravity must be addressed and determined through careful
experimentation or calculation.
POSITIVE LOAD ENGAGEMENT: Poor or inadequate sling-to-load
engagement results in the sling skipping across load edges. This
movement can result in catastrophic sling failure and uncontrolled
load descent. Slings equipped with protection have also been cut
because of poor sling-to-load engagement.
All sling users must be trained on the proper use of slings.
The American Society of Mechanical Engineers, in the ASME B30.9
Sling Safety Standard, clearly establishes the requirement for
training. Section 9-X.1-Training states, Sling users shall be
trained in the selection, inspection, cautions to personnel,
effects of the environment and rigging practices, covered by this
chapter.
DOL/OSHA Guidance on Safe Sling Use (29 CFR 1910.184) states
that a qualified person is one: who by possession of a recognized
degree or certificate of professional standing in an applicable
field, or who, by extensive knowledge, training and experience has
successfully demonstrated the ability to solve or resolve problems
relating to the subject matter and work.
It is important that all sling users be knowledgeable about the
safe and proper use and application of slings and be thoroughly
familiar with manufacturers recommendations and all safety
information provided with products. In addition, sling users need
to be aware of their responsibilities as outlined in all applicable
standards and regulations. If you are unsure whether you are
properly trained or knowledgeable, DO NOT use slings or rigging
devices until you are absolutely sure of what you are doing.
Slings must be protected from damaging edges, corners,
protrusions or abrasive surfaces by materials of sufficient
strength, thickness and construction to prevent sling damage and
failure.
There are a variety of ways to employ sling protection and
prevent sling damage. Regardless of the particular method chosen,
the goal is to ensure that the sling maintains its ability to
securely lift the load while avoiding contact with damaging or
abrasive surfaces under tension. A qualified person must carefully
consider the appropriate means to accomplish this goal by selecting
sling protection appropriate for the types of exposure damage.
Sling protection should not be makeshift (i.e., selecting and using
cardboard, work gloves or other such items that were not designed
to serve as protection devices).
Sling protection may not prevent cutting or other forms of
damage. To avoid severe personal injury or death, personnel should
be kept away from the load and never be under or near the load,
while it is being lifted or suspended. Personnel should never be
next to rigging under tension.
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GEN
ERAL
INFO
. AND
TRAININGPurchase and Use Considerations
CHEMICAL FACTORS
ENVIRONMENTAL CONSIDERATIONS
Chemically active environments can affect the strength of
rigging products in varying degrees from moderate to total
degradation. The materials used in the construction of slings and
components must be compatible with the mechanical and environmental
requirements imposed. Fumes, sprays, mists, vapors and liquids of
acids or alkalis can degrade rigging products. The chemical agents
must be identified. Specific time, temperature and concentration
factors will assist the user and manufacturer in the selection of
the appropriate sling material components.
It may be necessary to conduct an on-site suitability test. A
sample would be subjected to exposure, under no load. The length of
exposure must be determined by the qualified person. After
exposure, the sample would be pulled to destruction to determine
the retention of tensile strength and evaluated, comparing test
results with the strength of an unexposed, control sample. We
prefer application testing to chemical analysis of independent
chemical agents done by referencing various charts or technical
bulletins. Application testing (where the rubber meets the road)
will also provide more accurate information on the cumulative
effects of multiple chemical agents. We will match your efforts and
assist you in determining the most suitable materials for your
specific application.
TEMPERATURE:
Conventional synthetic products cannot be used in environmental
or contact temperatures exceeding 194F/90C or below -40F/-40C.
Applications outside those parameters can be addressed by
consulting us for specific recommendations.
ULTRAVIOLET (UV) LIGHT DEGRADATION:
Exposure to sources of ultraviolet (UV) light affects the
strength of synthetic products in varying degrees from slight to
total degradation. Factors which play a part in the degree of
strength loss are length of exposure, sling construction and
design. Other environmental factors such as weather conditions,
elevation and geographic location also affect the degree of
degradation.
The Web Sling and Tie Down Association (WSTDA) conducted tests
to determine the affects of strength loss, as a result of
ultraviolet (UV) exposure. The report, WSTDA-UV-Sling-2003 is
available at www.wstda.com
Many different variables were analyzed in slings that were
exposed for a period of 36 months. Nylon and polyester endless
slings featuring: treated and untreated webbing, 6800 Lbs. (class
5) and 9800 Lbs. (class 7) materials and single and double ply
constructions were evaluated.
Initially, nylon web slings lost strength at a slower rate, when
compared to polyester slings, but continued to lose strength as
exposure time was extended. The loss of strength for nylon slings
can be 40 to 60% after exposure periods ranging from 12 to 36
months.
In the first year of the study, polyester web slings lost
strength at a greater rate, when compared to nylon slings. Loss in
strength for polyester slings was approximately 30% after 12 months
exposure. Polyester sling strength loss seemed to subside and level
off after the initial 12 month period.
When slings are not in use, store them in a dark, cool, dry
location, free from mechanical and environmental damage.
MOISTURE ABSORPTION:
When nylon products are wet there is an approximate strength
loss of 15%. This loss of strength is documented in the 1988 DuPont
Technical Information Multifiber Bulletin X272, page 6. Nylon sling
strength returns when the sling dries completely. Polyester and
High Performance Fiber strength is unaffected by moisture
absorption.
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Sling Hitches
A BASKET WORK LOAD LIMIT OF 10,000 LBS.CHANGES AS THE SLING TO
LOAD ANGLE CHANGES
AT 90 - WORK LOAD LIMIT = 5,000 LBS. PER LEGAT 60 - WORK LOAD
LIMIT = 4,330 LBS. PER LEGAT 45 - WORK LOAD LIMIT = 3,536 LBS. PER
LEGAT 30 - WORK LOAD LIMIT = 2,500 LBS. PER LEG
SLING-TO-LOAD ANGLE (DEGREES) 90 60 45 30
WORK LOAD LIMIT X LOSS FACTOR 10,000 Lbs. x 1.000 10,000 Lbs. x
.8660 10,000 Lbs. x .7071 10,000 Lbs. x .5000
REDUCED WORK LOAD LIMIT 10,000 Lbs. 8660 Lbs. 7071 Lbs. 5000
Lbs.
Sling-To-Load Angle
The Sling-to-Load Angle is the angle formed between a horizontal
line and the sling leg or body. The Sling-to-Load Angle has a
dramatic effect on sling Work Load Limits. Slings with adequate
capacity to handle the scale weight of the load have
catastrophically failed because the Sling-to-Load Angle and
increased tension were not taken into account.
This principle applies in a number of conditions, including when
one sling is used to lift at an angle and when a basket hitch or
multi-leg bridle sling is used. When selecting a sling, always
consider the Sling-to-Load Angle and the tension that will be
applied to the sling. As the Sling-To-Load Angle decreases, the
tension on the sling leg(s) increases.
Illustrated left- Increased tension ismagnified by any change
from verticalto horizontal lifting. Increased tensionis imposed on
the sling leg(s) when thelegs are used at angles less than 90.
Slings must be securely attached to the load and rigged in a
manner to provide for load control to prevent slipping, sliding
and/or loss of the load. A trained, qualified and knowledgeable
user must determine the most appropriate method of rigging to help
ensure load control and a safe lift.
For years sling users have used angles to determine sling
adequacy. One approach has been to determine the Sling-to-Load
Angle and multiply the Work Load Limit by the Loss Factor for the
specific angle. The result is the REDUCED WORK LOAD LIMIT.
1. Calculate the Sling to Load Angle.
2. Determine the corresponding Loss Factor.
3. Multiply the Work Load Limit (per leg) by the Loss Factor to
determine the reduced Work Load Limit (per Leg).
The result is the reduced Work Load Limit.
A
SLING-TO-LOAD ANGLE
The horizontal angle formed between the sling leg and the top of
the load.
Sling angles less than 30 should not be used, unless approved by
a qualified person.
SLING ANGLE - REDUCED WORK LOAD METHOD
LOSS FACTOR CHART
Angle A Degrees
Loss FactorAngle A Degrees
Loss Factor
90 1.000 55 .8192
85 .9962 50 .7660
80 .9848 45 .7071
75 .9659 40 .6428
70 .9397 35 .5736
65 .9063 30 .5000
60 .8660 25 .4226
3,536Lbs.
3,536Lbs.
2,500Lbs.4,330Lbs.
4,330Lbs.5,000
Lbs.5,000Lbs.
2,500Lbs.
CHOKER HITCH VERTICAL HITCH BASKET HITCH
Sling passes through one end around the load, while the other
end is placed on the hook. Load control is limited with only one
sling rigged in a choker hitch. A choker hitch will never provide
full 360 degree contact. For full contact use a Double Wrap Choke
Hitch. See page 24. The Choke Point should always be on the sling
body, not on the sling eye, fitting, base of the eye or fitting,
splice or tag.
One end is on the hook, while the other end is attached directly
to the load. Use a tagline to prevent load rotation.
The sling cradles the load while both eyes are attached
overhead. As with the choker hitch, more than one sling may be
necessary to help ensure load control.
Slings carry their loads in one of three primary sling hitches.
Most slings can be used in all three sling hitches, but some slings
are designed for use in only one hitch. Slings have the largest
Work Load Limit when used in a basket hitch. The vertical hitch
Work Load Limit is 50% of the basket hitch. The synthetic choker
hitch Work Load Limit is a maximum of 80% of the vertical hitch
Work Load Limit.
10,000 Lbs. 10,000 Lbs.10,000 Lbs.
10,000 Lbs.
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GEN
ERAL
INFO
. AND
TRAINING
10,000
Sling angles less than 30 should not be used, unless approved by
a qualified person.
Sling-To-Load Angle
SLING ANGLE INCREASED TENSION METHOD
Choker Hitch Angle
Whenever a sling is used in a choker hitch and results in a
Choker Hitch Angle less than 120 degrees, Choker Work Load Limits
must be adjusted. Determine the Choker Hitch Angle and multiply the
Choker Hitch Work Load Limit by the appropriate Reduction Factor.
The result is the actual, reduced Choker Work Load Limit.
A more salient approach to determine sling adequacy is the
calculation of INCREASED TENSION resulting from the Sling-to-Load
Angle. This approach has the distinct advantage of enabling the
sling user to determine the required sling strength requirement.
The user must first determine the angle and multiply the load
weight (per leg) by the tension factor for the specific angle. The
result is the INCREASED TENSION or actual loading on the sling
leg(s).
1. Calculate the Sling to Load Angle.
2. Determine the corresponding Tension Factor.
3. Multiply the load weight (per leg) by the Tension Factor to
determine the increased tension on the sling leg(s).
TENSION FACTOR CHART
ANGLE A DEGREES
TENSION FACTOR
ANGLE A DEGREES
TENSION FACTOR
90 1.000 55 1.221
85 1.004 50 1.305
80 1.015 45 1.414
75 1.035 40 1.555
70 1.064 35 1.742
65 1.104 30 2.000
60 1.155 25 2.364
CHOKER HITCH ANGLE REDUCTION CHART
Choker Hitch Angle (Degrees)
Reduction Factor
120 - 180 1.00
105 - 120 .82
90 - 105 .71
60 - 90 .58
0 - 60 .50
0-30
60
90
120180135135
SLING TENSION INCREASES AS THESLING-TO-LOAD ANGLE DECREASES
AT 90 - SLING TENSION = 5,000 PER LEG AT 60 - SLING TENSION =
5,775 PER LEGAT 45 - SLING TENSION = 7,070 PER LEGAT 30 - SLING
TENSION = 10,000 PER LEG
5,000Lbs.
5,000Lbs.
10,000
SLING-TO-LOAD ANGLE(DEGREES)
90 60 45 30
LOAD WEIGHTX TENSION FACTOR
10,000 Lbs.X 1.000
10,000 Lbs.X 1.155
10,000 Lbs.X 1.414
10,000 Lbs.X 2.000
INCREASED SLING TENSION 10,000 Lbs. 11,550 Lbs. 14,140 Lbs.
20,000 Lbs.
Two examples of slings used at 0 degree Choker Hitch Angle.
Controlling a load witha high center of gravity.
Rigging from a Supporting Structure.
Supporting StructureChoker Hitch Angle
Choker Hitch
Angle at 0 degree.
Choker Hitch
Angle at 0 degree.
10,000Lbs.
LOAD
10,000Lbs.
5,775Lbs.
5,775Lbs.
10,000
7,070Lbs.
7,070Lbs.
10,000
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It is always important to rig and control the load so that
stability is achieved. Determining the location of the Center of
Gravity (CG) is vital to achieving load control. The CG is the
point where the load weight is concentrated and is the balance
point for an object. The Center of Gravity when suspended will:
1. Unless restrained, the CG will move directly under the
suspension point.
2. The CG will move to the lowest point possible.
For best control, attach the slings above the CG. When this is
not possible keep the CG contained with three or four sling legs or
use basket or choker hitches with wraps. These measures may not
guarantee load control. The user must be assured, based upon the
specific application that selected methods are suitable and comply
with all applicable standards and regulations.
Multiple factors must be taken into consideration to ensure that
load control and stability are attained. A load with a high center
of gravity can rotate in certain sling hitches.
Lift point is below CG
and only two slings used.
StableUnstable
(After)(Before)
Lift point is not over CG.
Load will shift until CG settles
below the suspension point.
Calculating the tension imposed on slings or individual legs of
a multi-part sling system will enable the sling user to select
slings with adequate Work Load Limits.
1) Determine the Load Angle Factor (LAF):
Divide the leg Length (L) by the Headroom (H)
L H = LAF
Example: 20 15 = 1.33 Load Angle Factor (LAF)
2) Determine the Share of the Load (SOL) for the individual
sling legs:
Divide the load weight by the number of sling legs.
Load weight number of legs = Share of the Load (SOL)
Example: 12,000 Lbs. 3 legs = 4,000 Lbs. (SOL)
3) Multiply Load Angle Factor by the Share of the Load
to determine Sling Tension.
Load Angle Factor x Share of the Load = Tension
LAF x SOL = Tension
Example: 1.33 x 4,000 = 5,320 Lbs.
H(15 Ft.)
Please Note: Tension calculations are based upon:1) Sling
attachment points being equidistant from the center of gravity.2)
Sling attachment points being equidistant to each other.3) Sling
attachment points being on the same horizontal plane.4) Equal sling
leg lengths.
L(20 Ft.)
Use the following steps to calculate the tension imposed upon
the individual sling legs, when you know the leg Length (L) and
Headroom (H).
Sling Tension - Leg Length/Headroom
Unstable
Center of Gravity (CG)
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GEN
ERAL
INFO
. AND
TRAININGAdvanced Tension Calculations
Different, complex calculations are required to determine sling
tension when the slings are attached at different horizontal
planes. (Please note: Twin-Path Adjustable Bridle is depicted).
More complex calculations are required when the slings are not
placed equidistantly from the center of gravity or when the Center
of Gravity is not equidistant from the sling attachment points. The
PROPORTIONAL SHARE OF THE LOAD (SOL) must be determined and
multiplied by the LOAD ANGLE FACTOR (LAF) to determine SLING
TENSION.
Sling tension is a function of sling length, distance between
the sling attachment points and the spatial relationship between
the sling attachment points and the Center of Gravity. An inverse
proportional relationship exists between Distance and Share of the
Load. If a sling is attached 25% of the distance from the Center of
Gravity, that sling will carry 75% of the load weight. Likewise, if
a sling is attached 75% of the distance from the Center of Gravity,
that sling will carry 25% of the load weight.
SLING TENSION - DIFFERENT HORIZONTAL PLANES
SLING TENSION - PROPORTIONAL SHARE OF THE LOAD
55,000 Lbs.
5ft (H)
6ft (L1) 10.5ft (L2)
3ft. 9ft.
12ft.
6 FT. LEG3
12ProportionalShare ofthe Load
x
Load Angle Factor
= .25 Distance from CG .75 Share of the Load
.75 x 55,000 = 41,250 Lbs.
L1
H
6
5= = 1.20
x
Sling Tension 49,500 Lbs.
10.5 FT. LEG
x
9
12ProportionalShare ofthe Load
x
Load Angle Factor
= .75 Distance from CG .25 Share of the Load
.25 x 55,000 = 13,750 Lbs.
L2
H
10.5
5= = 2.10
Sling Tension 28,875 Lbs.
W x d2 x L1
(d2 x H1) + (d1 x H2)
14,600 x 12 x 13
(12 x 11.5) + (6 x 16)
2,277,600
234
9,733 Lbs.TENSION
13 FT. LEG (L1)SLING TENSION
W x d1 x L2
(d2 x H1) + (d1 x H2)
14,600 x 6 x 20
(12 x 11.5) + (6 x 16)
1,752,000
234
7,487 Lbs.TENSION
20 FT. LEG (L2)SLING TENSION
14,600 Lbs.
11.5 ft(H1)
18 ft
12 ft(d2)
6 ft(d1)
20 ft(L2)
16 ft(H2)
13 ft(L1)
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Rigging and Hitch Information
GENERAL INFORMATION ADJUSTABLE BASKET HITCH
Slings should be rigged in a manner that provides proper load
control. It is dangerous to use only one sling to lift a load which
tends to shift and slide out.
(One sling is depicted for illustrative purposes only).
Ensure that lifting devices are directly over the center of
gravity. If this is difficult to determine, it must be discovered
by cautious experimentation or calculation. Raise the load
carefully. If the load is not level, lower and correct the position
of the slings until the balance point is achieved and the load does
not tilt.
The adjustable basket hitch allows the sling user to adjust the
length of the legs to raise the load level. Adjustable hitches are
particularly useful with loads having uneven load weight
distribution resulting in an off-set center of gravity.
The Adjustable Basket Hitch Work Load Limit is identical to the
regular basket hitch rating. The rating must be adjusted for the
Sling-to-Load Angle. Another effective solution is an Adjustable
Rope Sling featured on pages 127 and 128.
BASKET HITCHES
Inverted basket hitches are referred to as equalizing hitches
because the sling is free to slip through the hook based upon the
load weight distribution. Be sure to employ the four ends down,
North to South, load engagement system.
Extra care should be taken when using slings in a basket hitch
to balance the load to prevent slippage.
As with the choker hitch, more than one sling may be necessary
to control the load.
Slings skipping through hardware components can become damaged.
Balancing the load is critical and necessary to prevent sling
damage and failure.
If practical, take a full wrap around the load to grip it
firmly; be sure when using multiple slings that they do not cross
over each other. Wrapping the load is a legitimate method of
minimizing excessive sling length. Other methods, such as, twisting
and knotting radically reduce sling Work Load Limits. When the load
is wrapped the sling Work Load Limit is not increased, but load
control is.
WrongInverted Basket(East to West)
RightEye & Eye Slings (North to South)
Right Wrong
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GEN
ERAL
INFO
. AND
TRAININGRigging and Hitch Information
CHOKER HITCHES
The choke hitch should always be pulled tight before the lift is
made, not pulled down during the lift. A sling rigged in a choker
hitch (not double wrapped) does not make full contact with the
load. Use multiple slings to balance the load, and wrap the load to
ensure full contact. Ensure multiple slings do not cross. Choke on
opposite sides of the load, if this action will not damage the load
and maintain load control.
For a tighter choke hitch, which provides full, 360 contact with
the load, take a full wrap around the load before choking the
sling. Ensure that multiple slings do not cross. When the load is
wrapped the sling Work Load Limit does not increase, but load
control does.
Please note:One sling is depicted for illustrative purposes
only.
Always use a choker hitch when turning a load. If the sling is
not rigged properly, the turning action will loosen the hitch,
resulting in load slippage. Place sling eyes on top of the load,
pointing the opposite direction of the turn. The body is then
passed under the load and through both eyes. Blocking should be
used to protect the sling and facilitate removal. Basket hitches
should not be used to turn a load. Always downgrade the choker Work
Load Limit when the angle of choke is less than 120, see page
20.
The sling should be of sufficient length to ensure that the
choke action is on the sling body, never on the sling splice,
fittings, tag, eye or at the base of the sling eye or fitting.
ADJUSTABLE HITCH DOUBLE CHOKER HITCH
The Adjustable Hitch allows the sling user to adjust the length
of the legs to raise the load level. Adjustable hitches are
particularly useful with loads having uneven load weight
distribution resulting in an off-set center of gravity. The Work
Load Limit for the Adjustable Hitch is identical to the normal
Vertical Work Load Limit. The Adjustable Hitch works reasonably
well on narrow web slings (1 and 2 in. widths) and roundslings
rated at less than 7000 Lbs. choker.
The Double Choker Hitch if applied properly will facilitate
equalization of the loading on the sling legs over the lifting
hardware. If applied improperly, one of the legs will share a
greater portion of the load and equalization will not occur. The
Double Choker Hitch Work Load Limit is twice the regular Choker
Hitch Work Load Limit.
smaller
larger
Right Wrong
Right Wrong
Right Wrong
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Web Sling Safety Information
SYNTHETIC WEB SLING SAFETY BULLETIN
To detect possible damage, you should perform a visual
inspec-
tion of the entire sling and also feel along its entire length,
as
some damage may be felt more than seen. You should look and
feel for any of the types of conditions listed in Table 1. Table
2
shows examples of some of these types of damage, but note
that
they are relatively extreme examples provided for
illustration
purposes only.
WARNING
SyntheticWeb Sling Safety Bulletin
2. Slings Must Be Regularly and Properly Inspected
1. All Sling Users Must be Trained and Knowledgeable 2a. How to
inspect slings
2b.What to do if you identify damage in a sling
If you identify ANY of these types of damage in a sling,
even if the damage you feel or see
is not as extensive as shown in the pictures in Table 2. Slings
that
are removed from service must be destroyed and rendered
completely unusable unless they can be repaired and proof-
tested by the sling's manufacturer or other qualified person.
You
should never ignore sling damage or attempt to perform
temporary field repairs of damaged slings (e.g., tie knots in
the
webbing, etc.).
remove
it from service immediately
All web sling users must be trained on the proper use of web
slings. The American Society of Mechanical Engineers, Safety
Standard for Slings (ASME B30.9) states:
OSHA Guidance on Safe Sling Use (29 CFR 1910.184) states that
a
"qualified person" is one:
It is important that all sling users be knowledgeable about
the
safe and proper use and application of slings and be
thoroughly
familiar with the manufacturer's recommendations and safety
materials provided with each product. In addition, all sling
users
need to be aware of their responsibilities as outlined in
all
applicable standards and regulations.
If you are unsure whether you are properly trained and
knowledgeable, or if you are unsure of what the standards
and
regulations require of you, ask your employer for
information
and/or training use web slings until you are
absolutely sure of what you are doing. Remember, when it
comes to using web slings, lack of skill, knowledge and care
can
result in severe or to you and others.
"Synthetic webbing sling users shall be trained in the
selection, inspection, cautions to personnel, effects of the
environment and rigging practices as covered" by Chapter
9-5.
"who, by possession of a recognized degree or certificate of
professional standing in an applicable field, or who, by
extensive knowledge, training, and experience, has
successfully demonstrated the ability to solve or resolve
problems relating to the subject matter and work."
DO NOT
INJURY DEATH
Even seemingly "minor" damage to a web sling can
significantlyreduce its capacity to hold or lift objects and
increases thechance that the sling will fail during use. For
example, one slingmanufacturer has shown that a 3/8" (9.5mm) cut
(much smallerthan the cut shown in Table 2) caused a sling to break
under loadat almost half its non-damaged capacity. Therefore, it is
veryimportant that web slings are regularly and properly inspected.
If
you are not sure whether a sling is damaged, .DO NOT USE IT
The entire web sling must be and itshall be if ANY of the
following aredetected:
inspected regularlyremoved from service
Table 1.Web sling removal from service criteria
This bulletin contains important safety information about the
use of synthetic web slings.
However, it contain all the information you need to know about
handling, liftingand manipulating materials and loads safely. Sling
use is only one part of a lifting system and itis your
responsibility to consider all risk factors prior to using any
rigging device or product.
Failure to do this may result in severe or due to sling failure
and/or loss of load.
DOES NOT
INJURY DEATH
All users must be trained in sling selection, use andinspection,
cautions to personnel, environmentaleffects and rigging
practices.
Do not exceed a slings rated capacity. Alwaysconsider the effect
of sling angle and tension on theslings rated capacity.
Inspect sling for damage regularly, if the sling is
damaged, remove it from service.
Protect sling from damage. ALWAYS protect slings incontact with
edges, corners, protrusions, or abrasivesurfaces with materials of
sufficient strength,thickness and construction to prevent
damage.
Do not stand on, under or near a loadwith thesling under
tension. All personnel should be alert todangers of falling and/or
uncontrolled loads, slingtension and the potential for
snagging.
Maintain and store slings properly. Slings shouldbe protected
from mechanical, chemical andenvironmental damage.
4
If sling identification tag ismissingornot readable.
Holes, tears, cuts, snagsorembeddedmaterials.
Brokenorwornstitches in the loadbearingsplices.
Knots inanypartof theslingwebbing.
Acidoralkaliburns.
Melting, charring or weld spatter on any part of the
websling.
Excessiveabrasivewearorcrushedwebbing.
SignsofUltraviolet (UV) lightdegradation.
Distortion, excessive pitting, corrosion or other damageto
fitting(s).
If provided, exposed red core yarn. However if damage ispresent
and red yarns are not exposed DO NOT USE thesling.
Any conditions which cause doubt as to the strength
ofthewebsling.
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SYNTHETIC WEB SLING SAFETY BULLETIN
A three-stage procedure is recommended to help ensure that web
slings
are inspected with appropriate frequency:
Whenever a sling is initially received, it must be
inspected by a designated person to help ensure that the correct
web
sling has been received and is undamaged and that the web sling
meets
applicable requirements for its intended use.
The entire sling must be
Every sling must be inspected "periodically" by a
qualified and designated person. In order to validate the
frequent level
of inspection, the periodic inspection should be performed by
someone
other than the individual(s) who most commonly performs the
frequent
inspection. The frequency of periodic inspections is based on
the sling's
actual or expected frequency of use, severity of service
conditions, the
nature of the work performed with the sling and experience
gained
during the inspection of other slings used in similar
circumstances.
General guidelines for the frequency of periodic inspections
are:
Normal serviceyearly
Severe servicemonthly to quarterly
Special serviceas recommended by a qualified person
Periodic inspections intervals must not exceed one year.
Written records are not required for frequent inspections,
butWSTDA
WS-1 or ASME B30.9 require that a written record of the most
recent
periodic inspection be maintained. SeeWSTDAWS-1 or ASME B30.9
for
more information about definitions of Normal, Severe and
Special
service conditions.
Initial Inspection
Frequent Inspection inspected before each
shift or day in Normal service and before each use in Severe
service
applications.
Periodic Inspection
Environmental factors such as an exposure to sunlight, dirt or
gritty-type
matter and cyclical changes in temperature and humidity, can
result in
an accelerated deterioration of web slings. The rate of this
deterioration
will vary with the level of exposure to these conditions and
with the
thickness of the sling material. For example, single ply slings
will
generally degrade more rapidly with this exposure than multiple
ply
slings. Web slings that are used outdoors regularly should
generally be
permanently removed from service within a period of 2 to 4
years. All
web slings that are exposed to these conditions should be
highly
scrutinized during their inspections.
Visible indications of such deterioration can include the
following:
Fading of webbing color.
Uneven or disoriented surface yarn of the webbing.
Shortening of the sling length.
Reduction in elasticity and strength of the sling material due
to
an exposure to sunlight, often evident by an accelerated
abrasive damage to the surface yarn of the sling.
Breakage or damage to yarn fibers, often evident by a fuzzy
appearance of the web.
Stiffening of the web, which can become particularly evident
when web slings are exposed to outdoor conditions without
being used or cyclically tensioned.
You should always avoid any action that causes the types of
damage
identified in the previous section of this Safety Bulletin,
including (but
not limited to):
Dropping or dragging slings on the ground, floor or over
abrasive surfaces.
Pulling slings from under loads when the load is resting on
the
slingplace blocks under load if feasible.
Shortening or adjusting sling using methods not approved by
the sling manufacturer or qualified person.
Twisting, kinking or knotting the sling.
Exposing slings to damaging acids or alkalis.
Exposing slings to sources of heat damage or weld spatter.
Using slings or allowing exposure to temperatures above 194F
(90C) or below -40F (-40C).
"Tip loading" a sling on a hook instead of centering it in the
base
or "bowl" of the hook.
Using hooks, shackles or other hardware that have edges or
surfaces that could damage sling.
Running/driving over slings with a vehicle or other
equipment.
Synthetic slings are affected by some chemicals ranging from
little to
total degradation. Time, temperature and concentration factors
affect
the degradation. For specific applications, consult the
manufacturer. In
addition, water absorption can decrease the strength of nylon
web
slings by as much as 1015% (its strength returns when the sling
dries
completely). For specific applications, consult the
manufacturer.
Synthetic web slings can be damaged, abraded or cut as tension
and
compression between the sling, the connection points and the
load
develops. Surfaces in contact with the sling do not have to be
very
2c. How often to inspect slings
3b. Avoid actions that cause damage to slings
3c. Safeguard slings with sufficient protection
3a. Avoid environmental degradation
3. Slings Must be Adequately Protected from Damage
Cuts or tears Snags
Excessive abrasive wear
Holes/punctures Melting or charring Weld spatter
Acid/alkali burns Broken/worn stitches Crushed webbing Knots
Embedded materials
UV degradation Exposed red core yarns
Table 2. Types of damage you should look and feel for in web
slings
No UV Degradation
Faded From UV Exposure
Web Sling Safety Information
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SYNTHETIC WEB SLING SAFETY BULLETIN
abrasive or have "razor" sharp edges in order to create the
conditions for
sling failure. Therefore, web slings must ALWAYS
There are a variety of types of ways to protect slings from such
damage.
A qualified person might select and use appropriate
engineered
protectors/softenerscommercially available products (e.g.,
sleeves,
wear pads, edge wraps, body wraps, corner protectors, etc.)
specifically
designed to protect slings from damage. A qualified person might
also
design and construct their own methods of protection so long as
the
sling is adequately protected from and/or kept off of the
damaging edge
surface.
Regardless of the particular method chosen, the goal is to
ensure that
the sling, under tension, maintains its ability to securely lift
the load
while avoiding contact with damaging or abrasive surfaces
under
tension. A qualified person must carefully consider the most
appropriate
means to accomplish this goal. The protection used should not
be
makeshift (i.e., selecting and using cardboard, work gloves or
other such
items based solely on convenience or availability).
Regardless of the approach taken, a qualified person must ensure
that
the protection method chosen is appropriate for the types of
damage to
which the slings will be exposed. For instance, some protection
provides
abrasion resistance, but offers virtually no protection against
cuts.
Several "test" lifts, done in a non-consequence setting, may be
necessary
to determine the suitability of the protection device(s). After
each "test"
lift, the protection device(s) and sling(s) need to be inspected
for
damage and suitability. You should keep in mind that no
protection is
"cut proof" and you should always operate within the specified
limits of
the sling and its accessories (e.g., fixtures, hardware,
protection, etc.).
be protected from
being cut or damaged by corners, edges, protrusions or
abrasive
surfaces with protection sufficient for the intended
purpose.
When lifting loads, a trained, qualified and knowledgeable user
must
take into account the factors and issues addressed in this
bulletin, as well
as considering any other relevant factors not addressed herein
(see Table
4). Among the factors related specifically to web slings, users
must
perform several activities, including (but not limited to) those
discussed
in the following subsections.
Determine the weight of the load and make sure it does not
exceed
the sling's rated capacity or the capacity of any of the
components of
the rigging system. Users must also determine the load's center
of
gravity (CG) to make sure the rigging system used will be able
to retain
and control the load once lifted.
Select a sling having suitable characteristics for the type,
size and
weight of the load, the type of hitch (see Table 3) and the
environment.
The sling must be securely attached to the load and rigged in
a
manner to provide for load control to prevent slipping, sliding
and/or
loss of the load. A trained, qualified and knowledgeable user
must
determine the most appropriate method of rigging to help ensure
a
safe lift and control of the load.
4a. Assess the load
4b. Select an appropriate sling/configuration
4. Always Use Slings Properly
Safe handling, lifting and manipulation of materials and loads
requires consideration of a number of factors and issues,
including
(but not limited to):
Categories Issues/ Factors to Consider
Wind
Weather
Visibility
Environmental temperature
Object temperature
Chemical conditions and exposure
Ground stability
Underground installations
Weight
Dimensions
Center of Gravity (CG)
Attachment point integrity
Susceptibility to crushing/compression
Loose parts that could fall from load
Combination loads
Damaging surfaces/edges
Single/multiple cranes/hoists
Maximum/planned operating radius
Allowable load
Ratio of lift to allowable load
Clearance to surrounding facilities
Power lines and other environmental hazards
Clearance between boom and lift
Emergency/contingency set down area
Equipment inspection
Ensure a clear load path
Sling selection
Load control
Lift point (over the CG)
Positive sling-to-load engagement
Appropriate hitch (for CG and load control)
Load is free to move and is not snagged
Coordination of multiple slings
Suitable wear protection
Sling capacity is adequate for
angle and tension
Area clear of unnecessary personnel Signals: Visual, audible,
electronic, etc.
Personnel away from load and other dangers
Pre-lift plan and meeting
Tag lines/spotter requirements
Hitch Comments
Vertical
Hitch
Choker
Hitch
Basket
Hitch
Environment
Load
Equipment/Lift
Rigging
Personnel
Table 3. Common types of sling hitches
Table 4. Issues and Factors to consider when handling, lifting
and manipulating materials and loads
Sling passes through one end around
the load and the other end is placed onthe hook. Rated capacity
is normally 80%of that for a vertical hitch. Load control islimited
with only one sling rigged in achoker hitch. Also, the choke
pointshould always be on the sling bodynoton the sling eye,
fitting, base of the eyeor fitting, splice or tag.
One end is placed on the hook, while the
other end is attached directly to the load.
A tagline should be used to prevent load
rotation.
The sling cradles the load while both
ends are attached overhead. The rated
capacity for a basket hitch is twice that
for a vertical hitch. As with the choker
hitch, more than one sling rigged in a
basket hitch (or some other means) may
be necessary to help ensure load control.
Web Sling Safety Information
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SYNTHETIC WEB SLING SAFETY BULLETIN
Where to Find Additional Information
Synthetic Web Slings.
ASME B30.9Synthetic Webbing Slings: Selection, Use
andMaintenance.
OSHA 29 CFR 1910.184Slings. Rigging handbooks.
OSHA Guidance on Safe Sling Use.
Manufacturers catalog, manual, website, bulletins, etc. Formal
training provided by manufacturers or other outsideentities.
Angle A
in degrees
from horizontal
Tension
Multiplier
90 1.000
85 1.004
80 1.015
75 1.035
70 1.064
65 1.104
60 1.155
55 1.221
50 1.305
45 1.414
40 1.555
35 1.742
30 2.000
Angle of Choke
(degrees)Angle of Choke
Reduction
Factor= >or