4 .9 Interpretation and Use of Readings 



The readings obtained by the Magnograph should be used 

 to pinpoint areas of a rope which require further visual 

 inspection but should not be considered as a wholesale 

 replacement of visual inspection. 



By keeping accurate histories of rope wear, problem 

 areas in the hoisting system or in rope usage will be- 

 come quite visible. Using this information will Allow 

 for more efficient rope use. 



4.9.1 Using Readings as a Rope Removal Criterion 



The decision to remove a rope from service due to loss 

 of strength is an individual decision for each user. 

 Rope removal is governed by legislation in many count- 

 ries and users should be aware of how this affects their 

 individual situation. 



The metallic area loss (LMA) on a cable is sometimes 

 used as a direct indication of loss of strength. 

 This is sometimes a good estimation or 'starting point' 

 but assumes that all ropes wear and lose strength in 

 the same manner. Even in countries where metallic area 

 loss is used as a direct indication of strength loss 

 considerable variation is found when this is compared 

 to the actual loss of strength. This is due to the 

 fact that many variables contribute to strength loss and 

 metallic area decrease is only one factor. If metallic 

 area loss were the only factor involved it too would 

 show considerable variation in loss of strength depend- 

 ing on where the loss has occurred in the rope. 



To achieve some guidelines on the correlation of the 

 readings of the instrument and how strength is being 

 lost in ropes of specific usage it is suggested that 

 actual breaking tests be done on a rope once removed 

 from service. This will allow the user to derive a 

 pattern of strength loss for his specific situation. 



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