Accident Prevention Manual

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• Accident Prevention Manual
• for Business Industry
• Engineering Technology
• 13th edition
• National Safety Council

Compiled by Dr. S.D. Allen Iske, Associate
Professor University of Central Missouri
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CHAPTER 17

• ROPES, CHAINS, AND SLINGS

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Ropes, Chains, and Slings

• The ability to handle materialsto move them from
  one location to another, whether during transit
  or at the worksiteis vital to all segments of
  industry.
• Materials must be moved, for example, in order
  for industry to manufacture, sell, and utilize
  products. In short, without materials-handling
  capability, industry would cease to exist.
• Ropes, chains, and slings require special safety
  precautions for use and storage.
• Know the properties of the various types of
  ropes, chains, and slings used.

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Types of Fiber Rope

• Manila fiberbest suited natural fiber for
  cordage
• Sisal fiber20 less breaking strength than
  Manila
• Acids and caustics deteriorate both manila and
  sisal fibers
• Other natural fibercotton, flax, straw,
  asbestos, silk, rawhide, and many others
• Synthetic fibernylon, polyester, and polyolefin
• used more often than natural fibers
• more known about their properties
• splices can be made readily and develop nearly
  full strength of rope

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Types of Fiber Rope

• Nylon rope
• has 2.5x the breaking strength of manila and four
  times its working elasticity
• highly resistant to organisms that cause mold and
  mildew
• breaking strength is reduced by 1015 when wet
  or frozen
• vulnerable to drying oils, mineral acids,
  phenols, and heat
• absorbs and stores energy in the same manner as a
  spring

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Types of Fiber Rope (Cont.)

• Polyester
• best general-purpose rope
• does not absorb moisture and retains full
  strength when wet
• it has half of the absorption capability of nylon
• shows little deterioration from sunlight and
  resists abrasive wear well
• safe operating temperature range is 20 to 180F

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Types of Fiber Rope (Cont.)

• Polyolefin
• similar to nylon and polyester
• highly resistant to a variety of acids
• it swells and softens when exposed to
  hydrocarbons, especially at temperatures above
  150F
• easily deteriorates under abrasion

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Types of Fiber Rope (Cont.)

• Composite rope
• made by combining several types of synthetic or
  combining synthetic and natural fibers
• can be made to match specific job requirements
• Other types of rope
• paper, glass, acrylic, rayon, pvc, rubber,
  cellulose acetate, fluorocarbon, and polyurethane

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Fiber Rope Working Load

• Working loads are for rope in good condition,
  with appropriate splices in noncritical
  applications, under normal service conditions,
  and under very modest dynamic loads.
• Exercise caution when using load ratings as the
  safety factor is not the same for all ropes.
• Rope use, condition, and exposure can affect the
  degree of risk to life and property.
• See Tables 17A and 17B for specifications.

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Working Load Selection

• Select a higher working load only with expert
  knowledge of conditions and a professional
  estimate of the risks involved.
• Working load figures generally do not apply when
  rope is subject to dynamic loading.
• Working load figures may apply for light dynamic
  loading, meaning the load is be handled slowly
  and smoothly to minimize dynamic effects.
• In towing lines, lifelines, safety lines, and
  climbing line applications, working loads in
  Tables 17A and 17B do not apply.

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Fiber Rope Inspections

• Inspect the entire length of new ropes before use
  to determine that no damage or defects exist.
• Any irregularity in appearance is evidence of the
  possibility of degradation or weakness.
• Under ordinary conditions rope must be inspected
  every 30 days.
• OSHA requires rope that is used to connect a load
  to a material handling device to be inspected
  each day before use.

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Fiber Rope Inspections (Cont.)

• External
• Examine the entire length of the rope inch by
  inch, for wear, abrasions, powdered fiber between
  strands, broken or cut fibers, displacement of
  yarns or strands, variation in size or roundness
  of strands, discoloration, and rotting.
• The fingernail test is a quick test for
  chemical damage.
• Internal
• Untwist the rope in several places to see whether
  the inner yarns are bright, clear, and unspotted.
• In rope with a central core, the core should not
  break away in small pieces when examined.

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Care of Fiber Rope in Use

• Recognize the effects of chafing, cutting,
  elasticity, diameter-strength ratio, and general
  mishandling.
• Do not drag rope.
• Handle twisted rope so it retains the amount of
  twist (balance) that the rope seeks when free and
  relaxed.
• Kinking strains the rope and may overstress the
  fibers.
• Avoid sharp bends over unyielding surfaces.
• Splice lengths of rope that must be joined, do
  not knot them.
• A proper splice will retain 100 strength, while
  a knot retains only 50.

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Care of Fiber Rope in Use (Cont.)

• Thoroughly dry rope that has become wet,
  otherwise it will quickly deteriorate.
• Do not allow wet rope to freeze if rope does
  freeze, completely thaw before use. Frozen fibers
  will break as they resist bending.
• Do not use wet rope or rope reinforced with
  metallic strands near power lines or other
  electrical equipment.

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Care of Fiber Rope in Storage

• Store away from fumes, heat, chemicals, moisture,
  sunlight, and rodents.
• Store in a dry place with circulating air, but
  air should not be extremely dry.
• Hang up small ropes and lay larger ropes on
  gratings so air can get underneath and around
  them.
• Do not store rope unless it has been cleaned.

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Wire Rope

• more widely used than fiber rope
• greater strength and durability under severe
  working conditions
• physical characteristics do not change when used
  in varying environments
• controlled and predictable stretch characteristics

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Wire Rope Classification

• The most widely used construction of rope are
  six-strand ropes of these two classifications
• 6 ? 19
• 6 ? 37
• There are other variations in rope sizes with
  different cores.
• The more wires per strand, flexibility increases.
• The fewer wires per strand, crush and abrasion
  resistance increases.

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Wire Rope Service Requirements

• Different jobs will require different types of
  ropes.
• Consideration of the properties of different rope
  types, core components, and strand count must be
  evaluated prior to selecting wire rope.
• Consult engineers from reliable rope
  manufacturers for assistance in rope selection.

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Design Factors for Rope Used in Hoisting

• Calculate by dividing the nominal catalog
  strength of the rope by the sum of the maximum
  loads to be hoisted.
• Federal, state, or locals codes may describe
  exactly how design and operating factors should
  be figured.
• Check what codes are in force before final
  selection.

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Wire Rope Inspection and Replacement

• OSHA minimum for wire rope or cable includes
  installation and yearly inspections. However,
  more frequent inspection is highly recommended.
• Rope should be inspected for crown wires,
  kinking, high strands, loose wires, nicking, and
  lubrication.
• Measure rope diameter and length for sudden
  changes that may indicate the rope is nearing the
  end of its useful life.

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Wire Rope Wear and Damage
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Wire Rope Inspection and Replacement

• Replacement is based on the number of broken
  wires per strand in one rope lay or on the number
  of broken wires per rope lay in all strands.
• OSHA specifications for unacceptable rope
• running ropes
• 3 broken wires in 1 rope lay and 6 random broken
  wires in 1 rope lay
• wire rope slings
• 5 broken wires in 1 strand in one rope lay and 10
  random broken wires in 1 rope lay

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Care of Wire Rope in Use

• Factors affecting rope condition
• vary widely corrosion and moisture cause wear
  that is dangerous and difficult to detect
• also kinks, fatigue, drying of lubrication,
  overloading, over winding, and mechanical abuse
• Recommendations for care
• Apply alkali and acid-free lubricants to clean
  and dry rope.
• Clean rope monthly with light lubricants and
  avoid cleaning fluids, which can damage the core.

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Sheaves and Drums

• Wire rope bending stresses depend on the diameter
  of drums and sheaves.
• Condition and contour of sheaves grooves is
  important for the service life of wire rope.
• Check sheave tolerances to ensure they are the
  correct size for the rope to be used.
• Avoid multi-layer winding of rope on drums when
  possible.
• If unavoidable limit the number of layers to
  three.

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Wire Rope Installation

• During the entire installation process make sure
  that
• The appropriate rope is attached to the drum.
• Appropriate tension on the rope is maintained as
  it is wound.
• Each turn is guided as close to the preceding
  turn as possible so that there are no gaps
  between turns.
• There are at least two dead turns on the drum
  when the rope is fully unwound during normal
  operating cycles.

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Wire Rope Installation (Cont.)
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Wire Rope Fittings

• Wire rope can be attached to fittings in a
  variety of ways depending on the needs of the
  job.
• Pressed fittings, mechanical sleeve splices,
  hand-tucked splices, clips and clamps, sockets,
  or knots are acceptable means of rope fittings.
• Maximum strength of an attachment is attained
  only when the connection is made according to the
  manufacturers instructions.

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Rigging

• The most important job of any lifting operation
  is rigging the load.
• It is estimated that 1535 of crane accidents
  may involve improper rigging.
• Loads vary in weight, physical dimension, and
  shape, therefore a rigger needs to know what
  method of attachment can be used properly.
• The single most important rigging precaution is
  to determine the weight of the load before
  lifting it.

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Fiber and Wire Rope Slings

• Safety considerations for rope sling assembly
• proper rope selection
• fittings suitable for the load
• selecting the proper fastening method
• proper selection of sling type
• proper hitch selection
• regular inspection and maintenance

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Fiber and Wire Rope Slings (Cont.)

• OSHA stipulates that fiber rope slings must be
  made with new fiber rope.
• Fiber rope is suitable for handling loads that
  would otherwise be damaged by contact from metal
  slings.
• Wire rope slings provide the greatest strength
  for slings.
• Cable-laid slings, made from multiple wire ropes
  laid into one rope structure, provide more
  flexibility than strand-laid slings.
• Braided slings are used where flexibility, high
  strength, and resistance to corrosion are
  essential.

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Fiber and Wire Rope Slings (Cont.)

• Methods of attachment
• All hooks and rings used as sling connections
  should develop the full capacity of the wire rope
  sling.
• Working load
• Reference rated load capacities given from
  manufacturer.
• Abrasion, nicking, distortion, corrosion, and
  bending will affect the load rating.

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Fiber and Wire Rope Slings (Cont.)

• Working load
• Use pads or saddles to protect ropes or chains.
• Thimbles spliced in the ends of slings will
  reduce wear.
• Consider the angle formed, as this greatly
  affects the working load of a sling.

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Angle Strength Loss from Rated Capacity

• Slings can be used at various angles.
• Rope stress increases rapidly with the angle of
  lift.
• Make adjustments in maximum load ratings based on
  the angle of the hoisting rope.
• The rated load capacity of the sling decreases
  sharply as the angle formed by the slings leg
  and the horizontal becomes smaller.
• When this angle is 45 degrees, the rated load
  capacity has decreased to 71 of the load that
  can be lifted when the legs are vertical.
• The actual stress is equal to the amount of the
  load that a leg must support, divided by the
  cosine of the angle that the leg is from the
  vertical.
• To avoid excessive angles, use longer slings, if
  head room permits.

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Angle Strength Loss from Rated Capacity
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Fiber and Wire Rope Sling Inspection

• Ensure a trained and competent person inspects
  the slings at least every 12 months.
• Employees should promptly report any questionable
  conditions.
• Immediately withdraw from service slings that
  fail inspection requirements.
• Ensure removed slings are unusable by further
  destroying them before they are discarded.

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Safe Operating Practices for Slings

• (ANSI/ASME) B30.9 recommendations for sling use
• load control
• load positioning
• inspections
• communication

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Chains and Chain Slings

• Alloy steel is the standard material for chain
  slings.
• Special purpose alloys are available.
• ASTM-approved alloy steel chains have minimum
  tensile strength of 115,000 psi and a minimum
  elongation of 15.
• Alloy steel chains are suitable for
  high-temperature operations.
• Always use a chain rated for a higher working
  load if severe impact loading may be encountered.

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Chain Sling Hooks and Attachments

• Should be made of identical or equivalent
  material to that of the chain.
• In emergency conditions that require replacement,
  select an attachment with extreme care.
• OSHA prohibits the use of makeshift links,
  fasteners, or other attachments.
• Handles attached to assembly hooks to prevent
  hand and finger injuries and can increase
  operating efficiency.

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Chain Sling Inspection

• Three types of inspections required
• initial inspection for new and repaired slings
• frequent inspections by the person handling it
  each time it is used
• periodic inspections on a semiannual or more
  frequent inspection by a competent person
• based on frequency of use, severity of service
  conditions, and service life

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Chain Sling Inspection (Cont.)

• Maintain documentation of inspections.
• The competent person should have authority to
  remove damaged assemblies from service.
• Link-by-link inspection is the best way to detect
  wear and stretching.
• Overall measurements of sling length, and even
  measurements of 1 to 3 ft are inadequate.
• Measure between the shank and narrowest point of
  the hook.

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Safe Practices for Chain Slings

• Purchase complete chain slings from the
  manufacturer and do not remove identification
  tags.
• Never splice a chain or put strain on a kinked
  chain.
• Remember decreasing the angle between the legs of
  a chain sling and the horizontal increases the
  load of the legs.
• See that the load is always properly set in the
  bowl on the hook.
• Store chains not in use in a suitable rack.

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Synthetic Web Slings

• Nylon and polyester are the fibers most commonly
  used.
• Each has advantages and disadvantages.
• Synthetic web slings can be cut easily and are
  not abrasion resistant.
• ASTM B783 states the minimum breaking strength
  shall be 5x the rated capacity.
• Sling capacity is reduced when used in a basket
  hitch when used with one crane hook.

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Synthetic Web Sling Inspection

• Initial
• Frequent
• Periodic
• OSHA requires synthetic web slings to be
  inspected each day before and during use

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Synthetic Web Sling Inspection (Cont.)

• Types of damage to look for
• excessive abrasive wear on webbing and any
  fittings
• cuts, tears, snags, punctures, holes, crushed
  fabric
• worn or broken stiches
• burns, charring, melting, or weld spatter damage
• knots
• chemical damage
• broken, distorted, or excessively worn fittings

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Metal Mesh Slings

• Classifications heavy duty, medium duty, or
  light duty
• All metal slings are proof tested to a minimum
  200 of their rated load capacity, which removes
  permanent stretching when used at rated load
  capacity.
• Safely handle sharp-edged materials, concrete,
  and high temperature materials up to 500F.
• The design factor of metal mesh slings is 5 to 1.

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Metal Mesh Slings Structure
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Safe Practices for Metal Mesh Slings

• Safe use depends on the use of the right sling
  for the right load and the construction of the
  sling.
• Any danger in their use stems mainly from
  improper use.
• Follow manufacturers recommendations for certain
  hitches.

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Metal Mesh Sling Inspection

• OSHA requires annual inspections by a qualified
  person.
• Initial, periodic, and frequent inspections are
  recommended.
• Maintain written inspection records.
• Look for signs of wear, lack of flexibility,
  visible distortion, and other indicators of
  damage.