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WEAR AND ABUSE

All wire ropes should be thorougly inspected at regular intervals. The longer it has been in service or the more severe the service, the more thoroughly and frequently it should be inspected. Be sure to maintain records of each inspection.

Inspections should be carried out by a person who has learned through special training or practical experience what to look for and who knows how to judge the importance of any abnormal conditions they may discover. It is the inspector's responsibility to obtain and follow the proper inspection criteria for each application inspected.

 
  Tension Break
Wire break shows one end of broken wire coned, the other cupped. Necking down of the broken ends is typical of this type break. Where tension breaks are found, the rope has been subjected to overloading, either for its original strength (new rope) or for its remaining strength in the case of a used rope. Tension breaks frequently are caused by the sudden application of a load to a slack rope, thereby setting up incalculable impact stress.
     
  Abrasion Break
Wire break shows broken ends worn to a knife-edge thinness. Abrasive wear obviously is concentrated at points, where the rope contacts an abrasive medium, such as the grooves of sheaves and drums, or other objects with which the rope comes into contact. Unwarranted abrasive wear indicates improperly grooved sheaves and drums, incorrect fleet angle, or other localized abrasive condition.
     
  Fatigue Break
Wire breaks are usually transverse or square showing granular structure. Often these breaks will develop a shattered or jagged fracture, depending on the type of operation. Where fatigue breaks occur, the rope has repeatedly been bent around too small a radius. Whipping, vibration, slapping and torsional stresses will also cause fatigue. Fatigue breaks are accelerated by abrasion and nicking.
 
  Corrosion Break
Easily noted by the wire's pitted surface, wire breaks usually show evidence of tension, abrasion and/or fatigue. Corrosion usually indicates improper lubrication. The extent of the damage to the interior of the rope is extremely difficult to determine; consequently corrosion is one of the most dangerous causes of rope deterioration.
     
  Cut or Shear
Wire will be pinched down and cut at broken ends or will show evidence of shear-like cut. This condition is evidence of mechanical abuse caused by agents outside the installation, or by something abnormal on the installation itself, such as a broken flange.

 

ABRASION Frozen sheaves or rollers
Tight grooves
Excessive fleet angle
Oversized or undersized rope
Corrugated sheave or drum
Sheave overspin
Rope jumping the sheave
Poor spooling
Misaligned sheaves
Site contaminants

Abrasion

CORE PROTRUSION
AND SLIPPAGE
Shockloading
Poor seizing techniques
Poor installation techniques

 


Core Protrusion (Shockloading)

 

CORROSION Lack of lubrication
Environmental damage, e.g., acidic
Fume exposure
Improper storage

 


Corrosion

 

CRUSHING Poor installation techniques
Crosswinding
Poor spooling
Incorrect wire rope construction
Poor break-in procedure
Excessive fleet angle
Excessive rope length

Crushing
DIAMETER REDUCTION Lack of lubrication (fiber core)
Excessive abrasion
Corrosion, internal and/or external
Inner wire or core failure
FATIGUE Out of round sheaves
Tight grooves
Misaligned sheaves
Undersized sheaves
Worn bearings
Vibration
Slapping
Whipping
Reverse bends

 


Fatigue (Reverse Bend)


Fatigue (Undersized Sheave)

 

HIGH STRANDING Poor seizing techniques
Tight grooves
Undersized sheaves
Poor installation techniques
JUMPING THE SHEAVE Poor spooling
Excessive rope length
Broken flange
KINKING Poor unreeling procedures
Poor installation techniques
Undersized sheaves
LAY LENGTHENING
& TIGHTENING
Poor installation techniques
Poor unreeling procedures
Corrosion
Core Failure
LOOPED WIRES Poor installation techniques
Undersized sheaves
UNBALANCED ROPE Oversized sheaves

 

 

 

 



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