When to Condemn(remove) wire rope from use + Numericals

"Condemn" means disapproval, unacceptable.

 A wire rope should be inspected before use to detect any of the above conditions so that its suitability (strength) may be estimated. 

• The "Docks Regulations 1934" require that a wire rope be condemned if in any length of 8 times its diameter, the total number of visible broken wires exceeds 10% of the numbe of wires in the rope or the rope shows signs of excessive wear, corrosion or other defect which in the opinion of the person who inspects it, renders it unfit for use.

The explanation for the above statement: 

• If 10% or more from the total number of wires is found broken in the length of (8 x dia) of the wire rope is condemned.

Example:

In 6x12 wire rope, dia 15mm has 10 broken wires.

Ans:

Total number of wires => 6x12 = 72 wires

Inspection length (8 times the dia)=> 8x15 = 120mm

10% of total no. of wires => (10x72)/100 = 7.2 wires

*For the inspection length of 120mm, more than 7.2 broken wires are found, then the wire rope needs to be condemned.

*The actual broken wire is 10 wires (exceeded).

∴Yes, The wire rope has to be condemned.

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Numericals from Capt. Errol Fernandes book. Pg no. 130

1. State whether you would condemn the wire rope  in the following cases

Case ( i )

• A 6x24 wire 22mm in diameter has 15 broken wire in a length of 176mm.

Ans:

Total number of wires => 6x24 = 144 wires

Inspection length (8 times the dia) => 8x22 = 176mm

10% of total no. of wires => (10x144)/100 = 14.4wires

*For the inspection length of 176mm, more than 14.4 broken wires are found, then the wire rope needs to be condemned.

*The actual broken wire is 15 wires (exceeded).

∴Yes, The wire rope has to be condemned.

Case ( ii )

• A 6x37 wire 18mm in dia has 30 broken wires in a length of 2.16cm(216mm)

Ans:

Total number of wires => 6x37 = 222 wires

Inspection length (8 times the dia) => 8x18 = 144mm

10% of total no. of wires => (10x222)/100 = 22.2 wires

*For the inspection length of 144mm, more than 22.2 broken wires are found, then the wire rope needs to be condemned.

 

For 144mm = 22.2 wires

For 216mm = ?

=> (216x22.2)/144 = 33.3wires

*For the inspection length of 216mm, more than 33.3 broken wires are found, then the wire rope needs to be condemned.

*The actual broken wire is 30 wires (not exceeded)

∴NO need to condemn this wire rope.