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Application of Wire Rope Online Automatic Inspection System based on Weak Magnetic Principle on Quay

  Zou Xiaohua1, Zhu Jiashuang2, Xu Guochun2

  (1.Lianyungang New Oriental International Container Terminal Co., Ltd. Jiansu, Lianyungang, 222000;

  2. Lianyungang New Oriental Container Terminal Co., Ltd. Jiansu, Lianyungang 222000)

  Abstract:In order to solve the technical difficulty of quay crane wire rope inspection, wire rope automatic online real-time inspection system is researched and developed for safe monitoring of the full life cycle of the hoisting wire rope, trolley hauling wire rope and boom wire rope of quay crane. Machine intelligence inspection replacing manual inspection was consequently successfully realized. Efficient and comprehensive quay crane wire rope inspection has thus been improved. Remarkable cost benefit was subsequently achieved

  Keywords:port;wire rope inspection;weak magnetic inspection;

  As a great consumable component and high risk part of port lifting equipment, scientific and high efficient use of wire rope has a great potential to explore on the aspects of safe production, energy saving, operation cost reduction, improving equipment utilization, increasing output value, etc. For long time safe management of wire rope has been in an embarrassing condition of “being focused on by lack of technical measure”. In traditional inspection methods, manual inspection is still the major inspection measure. Hidden danger of rope failure cannot be eliminated.

  Lianyungang New Oriental Container Terminal Co., Ltd. (Hereinafter refers to as “the company”)applies weak magnetic inspection technology from Luoyang Wire Rope Inspection Technology Co., Ltd.(Hereinafter refers to as TCK.W)on safe

  monitoring of full life cycle of hoisting wire rope, trolley hauling wire rope, boom wire rope of quay crane. Machine intelligence inspection replacing manual inspection is successfully realized. Wire rope safe monitoring was brought to its highest state. Remarkable cost profit was gained.

  1 Major issue on traditional wire rope inspection method

  Rope failure of port lifting equipment is an important issue that has not been resolved in port industry. Due to complicated working condition and heavy duty cycle, broken wire, abrasion, corrosion, etc. on wire rope may occur. If there is no high efficient and reliable safety monitoring measure, wire rope defect will accumulate and quantitative change will convert to qualitative change which will finally lead to wire rope failure accident. Presently, traditional wire rope inspection methods have the following issues:

  1.1 Issue 1: Unsafe wire rope usage

  Rope failure risk due to strength loss always exists during wire rope usage. As far as port industry is concentered, casualty and property loss caused by rope failure every year occurs from time to time. US National Bureau of Production Safety made an investigation on 8000 wire rope users in the world and concluded that loss of wire rope strength for 10% wire rope still in service exceeds 15% which is in dangerous condition. Loss of wire rope strength for 2% wire rope in service exceeds 30% which is in extremely dangerous condition.

  1.2 Issue 2: Low efficiency of manual inspection of wire rope

  According to the Wire Rope Inspection and Maintenance and Replacement Regime of Lianyungang New Oriental International Container Terminal Co., Ltd., monthly inspection will be carried out for the first 18 months of wire rope operation. Twice per month of Inspection will be carried out from 19th to 22th month. Four times per month of inspection will be carried out from 23rd to 24th month. 5 people will take 4 hours to perform each inspection. Quay crane will stop working during such inspection. During 2 years life span of the hoisting rope, manual inspection time with crane stoppage is about 136 hours. Furthermore, visual inspection of wire rope by operator is about 10 minutes daily, low efficient manual inspection wastes a great deal of production time.

  1.3 Issue 3: Wire rope inspection result not reliable

  Due to the limitation of eyesight, people can only observe one angle within reach of eyesight during inspection, and cannot view the other angle. In most cases, light is insufficient for visual inspection due to environment and light factors. In some positions with narrow space or narrow observing angle, inspector has to inspect from far away, thus visual inspection is restricted greatly. Furthermore, even inspection speed is set as 0.3—0.5m/second, manual inspection can only detect partial external obvious defects of wire rope, while internal defects such as corrosion, abrasion, broken wire, especial fatigue cannot be discovered fundamentally, according to research and discovery on wire rope by an expert of the Soviet Union, when there is broken wire on external wire rope, internal unfound broken wires usually are 2.5 times of that of the external visible broken wires.

  1.4 Issue 4: Tremendous waste of wire rope usage cost

  Due to restriction and uncertainty of manual inspection, in order to ensure wire rope safety, users have to adopt the practice of “sacrificing cost for safety” by replacing rope periodically. That is, whatever the working condition of wire rope, when a certain time is reached, wire rope will be changed dogmatically. As per quay crane wire rope changing specification by Lianyungang New Oriental International Container Terminal Co., Ltd., under the condition of quarterly maintenance and greasing for imported wire rope, main hoist rope will be changed every 2 years, and trolley rope will be changed every two and a half year, boom rope will be changed every 8 years. The investigation result by USA shows that about 70% of compulsorily replaced wire ropes have little or even no loss of strength.

  2 Wire rope online automatic inspection system based on weak magnetic inspection principle

  TCK•W wire rope online automatic inspection system integrate weak memory regulation method, weak magnetic sensor technology, mode identification method, modern network communication technology, etc. It can not only inspect broken wire, abrasion, corrosion, fatigue, distortion high efficiently and accurately, and completely eliminate hidden danger of rope failure, but also for the first time resolve the technical difficulties encompassing NDT of quay crane wire rope for a long time such issues as daily evaluation on wire rope defect status, periodical evaluation on defect development trend, real-time alert for sudden hidden major danger have not been addressed.

  2.1 Technical principle of weak magnetic inspection

  Weak magnetic technology is an important achievement in the field of wire rope inspection which is the special magnetic vector status change and movement principle discovered by our scientist. Innovations:1. Theory innovation: establish new principle of spacial magnetic vector synthesis;2. Method innovation, discover new method of magnetic memory regulation;3. Technical innovation, invented weak magnetic inspection new technology. Breakthroughs are 1. Improvement from qualitative inspection to quantitative inspection;2. Machine intelligence inspection replacing manual inspection.

  This technology applies magnetic memory characteristics of ferro-magnetic material. In the microstructure of ferro-materials, a material-magnetic domain is arranged intensively. Each magnetic domain has a spin magnetic moment direction. If a certain direction of the magnetic domain is predominant, the material will show magnetism on the macroscopic scale. If the spin magnetic moment in the domain is in a disorderly state, there is no net magnetic moment. In the natural state, the spin magnetic moment direction of the magnetic domain in the wire rope is disordered, so it is hard to distinguish the material in normal or defective state by electromagnetic method at this time. If the magnetic energy is uniform and continuously distributed along the axial direction of the wire rope, the magnetic energy state in any magnetic domain should be equal and uniform. The magnetic field density and the magnetic flux are equal. If there exists any defective structure in the wire rope, the corresponding magnetic domain will show abnormality. The given magnetic field distribution memory is formed.

  Under repetitive mechanic load of pulling, bending, twisting of force on wire rope, material structure will generate deterioration such as broken wire, abrasion, corrosion, fatigue, etc. which leads to stress concentration. Magnetic force line has to arrange along irregular low energy consuming route in deteriorated volume element. Magnetic flux density will change accordingly. Magnetic energy products distribution is uneven and magnetic potential difference is formed in every volume element. The more serious the deterioration degree is, the more prominent the magnetic potential difference is. TCK.W Weak magnetic sensor is based on the innovative "spatial magnetic field vector synthesis" principle, given weak magnetic field modulation and demodulation, and magnetic memory formation of the physical field. By extracting the memory formation data of ferromagnetic materials, the defects of the steel wire rope can be identified quantitatively. By benchmarking the magnetic potential (the gradient of the electromagnetic field) characteristic information of normal volume element (The volume differential of the wire rope along the axial direction) memory of wire rope, and comparing it with other volume element information, we can effectively identify the magnetic potential difference caused by deterioration in the wire rope.

  By analyzing the quantitative relation between this physical fields variable information and corresponding mechanical bearing capacity, the technical objective of quantitative inspection of wire rope can be realized. See figure 1.

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Figure1 diagram of weak magnetic inspection principle

2.2 Level management mode of wire rope defect

Wire rope is a kind of flexible metal load bearing component. Once it is used, stress loss will surely occur progressively till it is discarded. Various levels of flaws and their irreparability will accompany the full service life of wire rope. In order to satisfy wire rope Non-destructive Test(NDT)requirement, TCK.W weak magnetic inspection technology strictly abides by wire rope applied mechanics check principle specified by the international standard, and considering abundant NDT practice data, developed professional software. Its realized core algorithm mode conforms to the fact and defines wire rope defect levels as follows.

Severe Flaw: Loss of Effective Metallic Are between 80-100% of upper limit of discard, real-time detectability 100%

Serious Flaw: Loss of Effective Metallic Area between 60-80% of upper limit of discard, real-time detectability 100%

Medium Flaw: Loss of Effective Metallic Area between 40-60% of upper limit of discard, real-time detectability >99%

Minor Flaw: Loss of Effective Metallic Area between 20-40% of upper limit of discard, real-time detectability >90%

Slight Flaw: Loss of Effective Metallic Area up to 20% of upper limit of discard, real-time detectability >80%

2.3 The system has four core abilities

(1) Ability of achieving high efficient and accurate inspection on broken wire, abrasion, corrosion, fatigue of wire rope.

(2) Ability of rapid and accurate determination of statistics on number of broken wire and various defects

(3) Ability of rapid and accurate measurement of wire rope diameter change (equipped with machine vision identification system)

(4) Ability of rapid and accurate positioning of defect

2.4 Unique advantage of the system

(1) Safety inspection for wire rope life cycle

(2) Synchronized inspection during high speed operation

(3) Machine intelligence identification replaces manual inspection

(4) Internet + wire rope remote diagnosis

3 Application of wire rope online automatic inspection system on quay crane

Lianyungang New Oriental International Container Terminal Co., Ltd. applies TCK.W quay crane wire rope online automatic inspection system, and for the first time in the world resolved the technical difficulty of quay crane wire rope online automatic inspection successfully. Multi groups of TCK.W magnetic memory inspection device, multi-function data collection work station are fixed on proper positions of operation route of quay crane hoisting rope, trolley hauling wire rope, boom hoisting rope and carry out real-time online automatic inspection for wire rope according to standard specification. Data collected is transmitted to cloud for storage through wire or wireless network. The processed inspection result made through cloud calculation technology shall be sent to first level of responsible unit (operator room). Operator in operator room thus can master current safe condition of wire rope. Once dangerous defects occur, the system can alarm immediately. The operator will take safety measures according to the alarm to prevent accident.

3.1 Installation positioning of quay crane wire rope online automatic inspection system

In view of main hoisting rope reeving and operation characteristics of quay crane, 95% of working section of quay crane hoisting rope passes the trolley platform. The working section of the hoisting rope on trolley is subject to bending, tension force during operation. That is the main zone where fatigue and broken wire are apt to occur mostly. By setting an inspection point on the hoisting rope pulley inlet on the trolley and arranging 4 weak magnetic sensors thus hoisting rope inspection can be achieved.

It only takes two steps to fully complete inspection of the hoisting rope.

(1) When trolley moves to position A, spreader lowers to the bottom and ascends to the top. This is the wire rope inspection of from spreader grab to position A.

(2) Trolley moves from position A to position B for inspection of wire rope A-B section.

Complete hoisting movement once by

moving to landside beam (position A) when

quay crane is working. Trolley moves from

landside end of beam to sea side end

(position B). We can see from these dual

inspections, it can inspect 95% of working

section of hoisting rope that fully satisfies the requirement of hoisting rope inspection. Refer to figure 2 for inspection installation point.

3.2 Installation point of quay crane trolley wire rope online automatic inspection system

According to quay crane trolley hauling wire rope reeving and working characteristics, set an inspection point on the sea side beam. Ropes at this position are steady during operation and ropes are not close to each other. Set an inspection point on the landside beam. Ropes at this position are steady. The section where ropes are easy to be damaged can be inspected to the maximum range. See figure 4 for inspection installation point.

3.3 Installation point of quay crane boom wire rope online automatic inspection system

Quay crane boom wire ropes have two lengths of ropes coming out of the drum (diameter 36mm). They control the boom up and down movement through fixed pulleys on trapezoid frame top and movable pulleys on sea side boom. In view of the wire rope operation condition, an inspection installation point is considered to be set at the fixed pulley of trapezoid frame top because wire ropes are steady during operation and it can inspect boom rope to the maximum length. See figure 7 for inspection installation point.

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4 Economic profit comparisons between wire rope online inspection technology and manual inspection

After market investigation and research, project was scheduled and executed in August 2018. Quay crane wire rope online automatic inspection system for Lianyungang Port New Orient Container Terminal Co., Ltd. was put into operation. Quay crane wire rope online automatic inspection was realized. Complete and

traceable report was generated. After on site proof for a period of time, good social and economic profit was obtained through comparison of wire rope online automatic inspection with traditional manual inspection. See table 1.

Table 1 Comparison of wire rope online automatic inspection and traditional manual inspection


Manual inspection

Wire rope online automatic inspection

1. Inspection method

Visual inspection, feel by hand, caliper measurement, rope speed 0.3- 0.5m/second

Not affected by rope speed, inspection done without interrupting normal operation

2. Inspection time5 people for each inspection, take 4 hours, 136 hour in 24 month24hours X365 days, Machine intelligence inspection replacing manual inspection
3. Energy consumption for inspection

Each manual inspection consumes electric power 3832KWh, 130000KWhw in 24 months

Inspection simultaneously with production in process. Energy consumption for inspection can be neglected.

4.Inspection effectManual inspection can only detect external defect of wire rope partially. Internal defects such as internal broken wire, abrasion, corrosion, fatigue cannot be detectedCapable of detect internal and external broken wire, abrasion, carrion, fatigue, deformation and other defects high efficiently and accurately. Eliminate hidden danger completely.

5. Inspection efficiency

Quay crane has to stop lifting workduring inspection. Shutdown formanual inspection takes 136 hoursduring lift span of hoisting rope

136 hours operation time is increased

during two years life span of hoisting

rope. If one quay crane has 30 moves

per hour, total 4080 moves can be

increased.

6. Reference of changing rope

Periodically or quantitatively change

rope

Correctly evaluate wire rope operation

condition, provide scientific reference

for changing rope

7. manpower cost

5 people for each inspection, take 4 hours, manpower cost is great

Machine intelligence inspection replaces manual inspection, save a lot of manpower cost

8.rope changing cost

periodically changing rope causes

great waster in rope usage

Safe condition of wire rope is always under control which provides inspection reference for scientifically extending service life of wire rope

9.Safety insurance

Internal defects including broken wire, abrasion, corrosion, fatigue can hardly be detected therefore major hidden danger exists

Wire rope safety under control in life span can fundamentally ensure safe service of wire rope.

10. Scientific managementRandom records and poor traceability cannot realize scientific management for wire rope life span.Automatically save all inspection result. Inspection data can be traced at any time. Enhance equipment management level scientifically.

5 Conclusions

Application of quay crane wire rope on line automatic inspection system has increased safety of quay crane wire rope and inspection intelligence level. It not only successfully realized the purpose of replacing manual inspection with Machine intelligence inspection, but also resolved the difficulty of wire rope safety management. Based on the operation parameters generated during quay crane wire rope operation, plus design parameter of wire rope, and also considering wire rope inspection and maintenance information and historic operation parameter, we can analyze and provide quay crane wire rope safety condition. Therefore related personnel may master the development trend of quay crane wire rope in its life span in real-time. Continuous and reliable operation of quay crane wire rope will be under high quality inspection and monitoring, which will ensure normal safe operation of quay crane. TCK.W wire rope automatic online inspection technology based on weak magnetic principle is China’s own advanced innovation technology. It brings in-process

safety monitoring to its highest state through continuous inspection during wire rope operation. This technology has gained Spotlight innovation award in 2018 Offshore Technology Conference (OTC) in USA. This is the first time nearly 50 years that Chinese technology has been awarded by OTC. This technology has also gained scientific advancement award of PLA(the People’s Liberation Army)of China. After applying this technology by Lianyungang New Oriental International Container Terminal Co., Ltd., safety operation of quay crane wire rope is always in all-round controlled monitoring condition. Inspection is done at the same time of production. These two processes of production and inspection are integrated into one. One work link is reduced and equipment working efficiency has increased. Energy consumption due to starting equipment dedicated to wire rope inspection is reduced. Such energy saving is remarkable. Finally this provides scientific inspection basis for extending wire rope service life and reducing wire rope usage cost.


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