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. 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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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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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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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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SLINGS
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
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