Ropes

Safe using of the various lifting machines like cranes, mine hoists, air rope ways, elevators etc. depends on steel wire ropes durability. Ropes are non repairable components of the machines. That is why the ropes worn or failed must be changed. 

There are regulations and standards, national and international, which fix requirements for the ropes [1-3]. 

Rejection criteria for the ropes resulting in durability loss, are defined by the regulations character and number of wires broken strand breakes friction wear corrosion ... 

Besides, for there is living time limitation for ropes being in use. A work fulfilled by a rope and performed in tone-kilometers may be used as a limit too. ... 

A visual method is considered by the most of regulations in force as a base for rope inspection. Instrumental methods using rope flaw detectors are considered as additional ones. But the visual methods have the number of shortcomings ... 

Evaluation data taken from the more than 8 thousand reports of the laboratory and field wire ropes inspections show that the visual methods and life time criteria are non adequate to real durability of the ropes in service [4]. The data show that only a very small percentage of all ropes was replaced in a proper time, when one has used a visual inspection. 

Electromagnetic NDT instruments allow to increase the test records reliability. They are most efficient for detection of the rope durability loss as a result of loss of metallic cross-sectional area (LMA) localized faults (LF) like broken wires, localized corrosion etc. 

If a wire is broken, a leakage of the magnetic flow arises. The leakage can be detected by a magneto sensitive sensor, e.g. by a Hall generator, as an electric pulse while a rope moves near the sensor. Of course, the pulses from inner broken wires are less and longer than from outer ones. 

Usually all the flaw detectors in service have two channels to detect defects of a rope the LMA and LF channels. The inspection information is recorded by a chart recorder or by a tape recorder. 

The first of them to determine the LMA quantitatively and the second - the LF qualitatively Of course, limit of sensitivity of the LF channel depends on the rope type and on its state very close because the LF are detected by signal pulses exceeding over a noise level. The level is less for new ropes (especially for the locked coil ropes) than for multi-strand ropes used (especially for the ropes corroded). Even if a skilled and experienced operator interprets a record, this cannot exclude possible errors completely because of the evaluation subjectivity. Moreover it takes a lot of time for the interpretation. Some of flaw detector producers understand the problem and are intended to develop new instruments using data processing by a computer [6]. 

The newest model of the INTROS, MDK-21 is intended to inspect round ropes of 6.. .64 mm. in diameter as like as flat ropes up to 233 mm width and 38 mm thickness. 

This is a double-channel flaw detector having their own microcomputer with 1 Mbyte memory to store data of the LMA and the LF channels for 800...2000 m of a rope under inspection. The instrument can be used in two modes as a tester for operative inspection or as a device for the inspection data storage. 

In the first mode a LMA value and number of wires broken per a lot of the rope length (definited in a number of the rope diameter) as like as a register of inspection data can be performed by the 4 digit LED display. After the inspection the data can be displayed in turn. 

Of course, all the data displayed on a computer can be printed as like as an inspection report (protocol) (see Fig. 1,2). The report contains inspection results in short the LMA readings divided in four levels number of LF per a lot of the rope length, e.g. per 6 dia. 

The report contains also other information which needs to be performed according to the standard [7] date, rope indification, rope diameter and construction, length of rope examined, inspection speed etc. Thus, a user gets the document obtained without very long and subjective data processing by a skilled and experienced operator. 

There are three changable sensor units for the MH-24/64 magnetic head as like as for MH-24. The units must be changed when rope diameter changes more than two times. The sensor units of the MH-40 and MH-54 are unchangable. So the MH-40 and MH-64 heads are more releable having no connectors for this. 

The INTROS Flaw Detector is able to inspect ropes moving through the magnetic head at speed 0...2 m/s. Limit of sensitivity to wire brake is 1% of the rope meatallic cross-section area, the LMA measure accuracy is not less than 2%. 

Calibration procedure bases on rope specimens and corresponds to the Standard Pratice ASTM 1574. It takes a piece of the rope under test having a nominal metallic cross-section area (LMA=0) to set zero point of the instrument. Rope section with the LMA value known is used to set the second point of LMA calibration charactiristics. It is possible to use the air point calibration when there is no rope in a magnetic head (LMA=100%). 

The INTROS Flaw Detector is certified by the Russian State Standard Service (GOSSTANDART) as well as approved by the Russian State Mining and Technology Safety Inspection (GOSGORTECHNADZOR). It is used to inspect mining hoist and crane ropes. Fig. 5 illustrates the INTROS use at the mining hoist of an Ural ore mine. The previous model of the instrument, MDK-11 was used to inspect ropes of the air rope ways in Caucasus and Kazakhstan in 1996. Fig. 6 shows the INTROS MDK-11 inspection of 45 mm skyline rope in Almaty, Kazakhstan. 

Geller and others Evaluation of Electromagnetic Rope Testers Joint Canadian/US Work, Materials Evaluation, vol. 50, no. 1, 1992, 56-63. 

R. Pryde New Developments in Non-Destructive Testing of Hoisting Ropes.-Mine Hoisting 96, International Scientific and Technical Conf, 8-10 Oct. 1996, Gliwice, Poland, in 2 vol., vol. 2, pp. 22-24. 

Standard Practice for Electromagnetic Examination of Ferromagnetic Steel Wire Rope, ASTM Standard E 1571-94. 

Rope location Skip hoist Install date 11/02/96 Mine VGOK Shaft Central Unit INTROS MDK21... 

Chandler D 1998 Finding transition pathways throwing ropes over rough mountain passes, in the dark Classical and Quantum Dynamics In Condensed Phase Simulations (Singapore World Scientific) pp 51-66... 

Bockrath M, Cobden D H, McEuen P L, Chopra N G, Zettl A, Thess A and Smalley R E 1997 Single-electron transport in ropes of nanotubes Science 275 1922-5. 

As with polyesters, the amidation reaction of acid chlorides may be carried out in solution because of the enhanced reactivity of acid chlorides compared with carboxylic acids. A technique known as interfacial polymerization has been employed for the formation of polyamides and other step-growth polymers, including polyesters, polyurethanes, and polycarbonates. In this method the polymerization is carried out at the interface between two immiscible solutions, one of which contains one of the dissolved reactants, while the second monomer is dissolved in the other. Figure 5.7 shows a polyamide film forming at the interface between an aqueous solution of a diamine layered on a solution of a diacid chloride in an organic solvent. In this form interfacial polymerization is part of the standard repertoire of chemical demonstrations. It is sometimes called the nylon rope trick because of the filament of nylon produced by withdrawing the collapsed film. 

Wire coating Wire, corded Wire covering Wire, electrical Wire enamel Wire insulation Wire materials Wire-rope machines Wires... 

Slit-Film Fiber. A substantial volume of olefin fiber is produced by slit-film or film-to-fiber technology (29). For producing filaments with high linear density, above 0.7 tex (6.6 den), the production economics ate more favorable than monofilament spinning (29). The fibers are used primarily for carpet backing and rope or cordage appHcations. The processes used to make slit-film fibers are versatile and economical. 

Olefin fibers are used for a variety of purposes from home furnishings to industrial appHcations. These include carpets, upholstery, drapery, rope, geotextiles (qv), and both disposable and nondisposable nonwovens. Fiber mechanical properties, relative chemical inertness, low moisture absorption, and low density contribute to desirable product properties. Table 7 gives a breakdown of olefin fiber consumption by use (73—75). Olefin fiber use in apparel... 

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