Nondestructive Assessment of Full Locked Coil (FLC) Ropes in Cage and Skip Winders
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Nondestructive Assessment of Full Locked Coil (FLC) Ropes in Cage and Skip Winders Debasish Basak Æ Srimanta Pal Æ Dipak Chandra Patranabis
Submitted: 22 April 2007 / in revised form: 12 June 2007 / Published online: 24 July 2007 ASM International 2007
Abstract Magnetic nondestructive evaluation is being used to assess the condition of full locked coil ropes used in cage and skip winders. Four locked coil ropes were studied for a period of 4 years. This paper focuses on the determination of the in situ condition of full locked coil ropes in cage and skip winders throughout this 4-year period. Keywords evaluation
Flaws Full locked coil Nondestructive
Introduction Visual inspection is the most conventional inspection method for wire ropes. Assessment of rope condition either by visual examination or even by drawing a specimen rope length and subjecting it to destructive evaluation seldom speaks about integrity of the entire rope length in the
installation. Electromagnetic and visual wire rope inspections complement each other. Both are essential for safe operation, and both methods should therefore be used for maximum safety [1]. Magnetic nondestructive evaluation is the process in regular use for assessment of rope condition. Equipment recently used for nondestructive evaluation of steel wire ropes generally use ‘‘permanent magnet method’’ [2]. This technique enables detection of (a) localized flaws e.g., broken wires (quantitative inspection) and (b) distributed flaws, namely, corrosion, abrasion, wear nicking, pitting, and so forth (qualitative inspection). A complete documentation of gradual rope deterioration throughout rope’s entire service life by periodic inspection after the rope installation would enable the operator to arrive at a decision to prevent rope failure under adverse conditions or to extend rope life in deserving cases.
Rope Condition Assessment D. Basak (&) Electrical Laboratory, Central Mining Research Institute, Barwa Road, Dhanbad 826001, India e-mail: [email protected] S. Pal Electronics & Communication Sciences Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700108, India e-mail: [email protected] D. C. Patranabis Department of Instrumentation and Electronics Engineering, Jadavpur University, Salt Lake Campus, Kolkata 700098, India e-mail: [email protected] D. C. Patranabis Heritage Institute of Technology, Kolkata 700107, India
Full locked coil (FLC) and half locked coil ropes are made of a spiral strand as its main core and finally covered with one or more layers of shaped wires (trapezoidal, round, and rail sections as in half locked coil or full locked sections). The final cover layer is made of full locked sections of wires that interlock each other and present a smooth surface. The outermost layer or cover is always laid in the opposite direction to the inner layers to make the rope ‘‘non-rotating’’ [3]. Two ropes of cage and two ropes of skip each of 28 mm diameter full locked coil construction (Fig
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