MATERIALS HANDLING

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MATERIALS HANDLING

• IN CONSTRUCTION

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SLING TYPES

• Generally one of six types
• Chain
• Wire rope
• Metal mesh
• Natural fiber rope
• Synthetic fiber rope
• Synthetic web

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THREE MAIN GROUPS

• Based on inspection procedures
• Chain
• Wire Rope and Mesh
• Fiber Rope Web

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ADVANTAGES DISADVANTAGES

• To choose the best sling look at the following
  factors
• Size
• Weight
• Shape
• Temperature
• Sensitivity of the material to be moved
• Environmental Conditions

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CHAINS

• Strength and Ability to Adapt to the load
• As with all slings, care should be taken to
  prevent damage.
• Sling failure has injured employees.
• Ideal for lifting hot materials-up to 1000º
• Visually inspect before each use-stretching, wear
  in excess of allowances, nicks and gouges.

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WIRE ROPE

• Consists of individual wires twisted to form
  strands.
• Strands are then twisted to form a wire rope.
• Fiber Core-more flexible but less resistant to
  environmental conditions.
• Wire Core-stronger and more resistant to heat
  damage.

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ROPE LAY

• The lay of the rope can mean one of three things
• One complete wrap of a strand is a One Rope Lay.

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STRAND DIRECTION

• Direction the strands are wrapped around the
  core
• Right Lay Rope is one where the strands are wound
  in a right hand direction.

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Direction of Wires in Strands to Direction of
Strands to Core

• Regular Lay Rope- wires in strands laid in one
  direction while strands in the rope are laid in
  the opposite direction.

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LANG LAY ROPE

• Lang Lay Rope- wires are twisted in the same
  direction as the strands.

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WIRE ROPE SLING SELECTION

• Four Characteristics to Consider When Selecting a
  Wire Rope Sling
• Strength function of size, grade
  construction.
• Must accommodate maximum load.
• Maximum load determined by multiplier.
• Ultimate strength is divided by multiplier to
  determine working load limit.

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THEREFORE
Ultimate Strength 10,000 lbs. Multiplier 5
Working Load Limit 2,000 lbs. New wire rope
slings have a design factor of 5. After use
ultimate strength is reduced. INSPECT!!
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FATIGUE
Result of the development of small cracks under
repeated applications of bending loads. (When
ropes make small radius bends) To prevent use
blocking or padding to increase the radius of the
bend.
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ABRASIVE WEAR
A rope withstands abrasion depending on its size,
number of wires and construction. Smaller wires
are more flexible but are less able to withstand
abrasion. Larger wires are just the opposite.
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ABUSE

• All factors being equal abuse will cause a rope
  to become unsafe long before any other factor.
• Therefore, safe practices and use of wire ropes
  must be strictly adhered to.

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WIRE ROPE LIFE

• Many operating conditions affect wire rope life
• Bending. Sling Design.
• Stresses. Materials Handled. Corrosion. Enviro
  nment. Loading Conditions. History of Previous
• Jerking (Speed). Use.
• Abrasion.

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WIRE ROPE SLING INSPECTION

• Visually inspect before each use.
• Check twists or lay of rope.
• If 10 randomly distributed wires in one lay are
  broken or 5 wires in one strand are damaged, the
  sling must not be used.
• End fittings and other components must also be
  inspected.

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FIELD LUBRICATION

• NO SET RULE.
• Depends on conditions under which slings are
  used.
• The heavier the loads, the greater number of
  bends, or the more adverse the conditions-the
  more frequently the sling should be inspected.

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STORAGE

• Well ventilated, dry building or shed.
• Never on the ground or left in weather.
• NOTE More frequently used slings give far more
  useful service than slings that are idle.

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DISCARDING SLINGS

• The following factors require discarding of
  slings
• Severe Corrosion.
• Localized wear on the outside (shiny spots).
• 1/3 reduction of outer wire diameter.
• Damage or displacement of end fittings.
• Distortion, kinking, bird caging, etc.
• Excessive broken wires.

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FIBER ROPE AND SYNTHETIC WEB

• For temporary work-construction, painting, and
  marine operations.
• Best choice for expensive loads, highly finished
  parts, fragile parts and delicate equipment.

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FIBER ROPE

• Preferred because they are pliant, grip the load
  and do not mar the surface of the load.
• Use on light loads.
• Not on objects with sharp edges and dont expose
  to high temps or chemicals.

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FIBER ROPE

• Choice of rope type and size depend on
  application, weight to be lifted and sling
  angles.
• Inspect carefully before use as rope slings
  deteriorate quicker than wire rope.
• Their strength is harder to estimate.

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INSPECTING FIBER ROPE

• Look at its surface-look for dry, brittle,
  scorched or discolored fibers.
• If noted, Supervisor should be notified to
  determine if it should be discarded.
• Check interior-should be clean with no powder
  build up.
• Scratch the surface-if fibers come apart it has
  suffered damage and should not be used.

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SYNTHETIC WEB SLINGS

• Many advantages.
• Made of nylon, dacron, polyester.
• Have the following common properties
• Strength
• Convenience
• Safety
• Load Protection

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COMMON PROPERTIES

• Long Life
• Economy
• Shock Absorbency
• Temperature Resistance

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UNIQUE PROPERTIES

• Nylon-use in neutral conditions or when alkaline
  or greasy conditions exist. Is resistant to
  chemicals and solvents.
• Dacron-use where high concentrations of acids
  exist. Alkaline deteriorates Dacron.
• Polyester-use where acids or bleaching agents are
  present and when minimum stretching is important.

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REMOVE IF DEFECTS EXIST

• Acid or Caustic Burns.
• Melting or Charring of any Part of the Surface.
• Snags, Punctures, Tears or Cuts.
• Broken or Worn Stitches.
• Wear or Elongation.
• Distortion of Fittings.

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PRIMARY SAFETY FACTORS

• 1. Size, Weight, and Center of Gravity.
• 2. Number and Angle of Legs.
• 3. Rated Capacity.
• 4. History, Care and Usage of the Sling.

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SIZE, WEIGHT, CENTER OF GRAVITY

• The center of gravity is considered to be where
  the entire weight of the load may be.
• The crane hook must be directly above the center
  of gravity of the load.
• Variations may cause tilting, stress on legs and
  potentially losing the load.

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NUMBER OF LEGS AND ANGLES

• As the angle decreases, the rated capacity of the
  sling decreases.
• The smaller the angle, the greater the stress on
  the sling leg.
• Heavier loads can be safely moved if the weight
  of the load is distributed among more sling legs.

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RATED CAPACITY

• Rated capacity of sling depends on type and size
  of sling and type of hitch.
• Manufacturers charts give ratings for new slings.
  Older slings must be used with more caution.
• Never exceed slings rated capacity.

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HISTORY OF CARE AND USAGE

• Mishandling and misuse are the leading cause of
  accidents.
• Protect from sharp bends and sharp edges.
• Properly Secure.
• Accurately determine weight and balance.
• Do not allow load to drag on ground.

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Proper Care, continued

• Position hook directly over the load.
• Seat sling squarely in hook bowl.
• Take up slack slowly-avoid jerking.
• Check tension-raise slowly and check for balance.
• Keep all personnel clear.
• Always use tag lines.

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ALWAYS OBEY THE NEVERS!

• Never allow more than one person to control a
  lift or give signals.
• Never raise the load more than necessary.
• Never leave the load suspended in the air.
• Never work under a suspended load.

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MAINTENANCE OF SLINGS

• CHAIN SLINGS
• Clean prior to each inspection.
• Look for Stretching, Binding, Wear, Nicks or
  Gouges.
• File heavy nicks and gouges, then check with
  caliper to ensure size is to recommendations.
• Check inside surface of links for wear.

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Maintenance, continued

• WIRE ROPE
• Clean prior to each inspection.
• Lubricated to manufacturers recommendations.
• Lubrication reduces corrosion and wear due to
  friction.
• Rope should be dry before lubricating.

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Maintenance, continued

• Fiber Ropes and Synthetic Webs- are generally
  discarded rather than repaired.
• Always follow manufacturers recommendations.

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