Innersheath

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Innersheath is provided over the laid up cores. It is provided to give circular shape to the cable and it provides bedding for the armouring. I.S. 1554 & I.S. 7098 permits following two methods of applying the innersheath of any thermoplastic material i.e. PVC, Polyethylene, etc.

a) EXTRUDED INNERSHEATH: Here the innersheath is provided by extrusion of Thermoplastic over the laid up cores. This type of the innersheath is generally provided in cables having round cores i.e in control cables and in power cables upto 10 sq.mm size.

b) TAPPED INNERSHEATH: Here the innersheath is provided by wrapping a thermoplastic tape over the laid up cores. It is generally employed in cables having sector shaped cored i.e. multicore cables of 16 sq.mm and above. This method saves a process and hence manufacturers always provide this type of innersheath unless the purchaser ask for extruded innersheath.