Diagnosis of Rolling Bearings using vibration and Acoustic Emission Technique |
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Takeo YOSHIOKA (THK Co. Ltd.) |
Characteristics of Acoustic Emission (AE), compared to those of vibration, to be used for diagnosis of rolling contact fatigue were stated in this report. A new compound sensor which simultaneously detects AE and vibration was developed based on those data. The evaluation demonstrated that the diagnostic performance of this compound was equivalent to that of each single AE and vibration unit.
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New Regulatory Inspection System and Condition Monitoring Techniques |
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Yukinori MAEKAWA (Nuclear and Industrial Safety Agency) |
To enrich regulations of nuclear power plants, Nuclear and Industrial Safety Agency repeated discussions. As a result, following three new approaches were proposed. Owners of nuclear power plants are expected to improve safety level by conducting more scientific maintenance practices.
[1] Collection of data on damages of equipments and its reflection to inspection
[2] Submission of maintenance plan and its prior confirmation by regulatory
[3] Enrichment of condition monitoring under operation with new technology
This new regulatory inspection system has started on January 1st, 2009.
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Condition Monitoring Verification and Maintenance Personnel Training |
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Takafumi MAEHARA (Japan Nuclear Energy Safety Organization) |
Under a new regulatory inspection system, confidence in functions of equipments and facilities is emphasized. It requires that owners of nuclear power plants should optimize maintenance practices by inducing new diagnostic technology. It also directs to adopt condition based maintenance instead of time based maintenance.
Prior to this tendency, Japan Nuclear Energy Safety Organization (JNES) started to improve condition monitoring maintenance techniques in 2006. From 2008, programs for inspection personnel using improved techniques and test facilities started. In the program, personnel learn techniques and know-how of inspections and investigations which will meet optimized maintenance practices in the future.
Also, anomaly simulations which are going to be conducted from the next fiscal year will be reflected in the programs.
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The Report of Condition Monitoring Technology (CMT) Session
"Accelerated aging test on rolling bearing" |
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Mitsuru UESAKA (University of Tokyo) |
The purpose of this session was to conduct accelerated aging tests using multiple practical techniques, and to create logical scenarios in order to quantitatively evaluate lifetimes of commercial rolling bearings.
Following three public researches achieved satisfactory results; evaluation of defect detectability using guided wave ultrasonic testing (UT) by Tokushima University, crack growth monitoring using Electromagnetic Acoustic Transducer (EMAT)-Eddy Current Testing (ECT) multi-sensor by Tohoku University, and real-time photography of rotating impellers using portable X-band linac by Tokyo University.
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Certification of ISO Machine Condition Monitoring Personel |
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Takuzo IWATSUBO (Kansai University) |
Beginning from SI unit, standardization has been developing beyond the originally expected range. The further standardization has developed, the more quality control to produce materials in the range of accuracy has become important. From this viewpoint, ISO9000 has been practiced. Recently, engineers in factories have also been standardized as a next step. For this, a certification system to classify engineers has been established.
The status quo and characteristics of this system was reported.
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Tribology and the System for Qualification and Assessment of personnel |
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Akio NITANAI (Tamagawa University) |
In October 2008, ISO18436-4 based on Tribology came into effect. This is related to qualification and assessment of engineers of condition monitoring and diagnostics of machines. In Japan, the Japan Society of Mechanical Engineers and Japanese Society of Tribologists have established a certification system conforming to ISO18436-4, which will start in October 2009.
To improve life cycle cost (LCC) of dynamic equipment, it is necessary to seek well-planned lubricant management and to effectively utilize equipment diagnosis by lubricating oil analysis. This system aims to educate engineers specialized in this field.
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Issues of Thermography Application and Motor Operated Valve Diagnostic Techniques |
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Akira HASEGAWA (The Japan Atomic Power Company) |
In nuclear power plants, acrylic covers for prevention of electric shock are used in cabinet panels and control panel. Since these covers shut out infrared radiation, we are now facing the following problems;
- Detectable thermal range with infrared cameras is limited
- It is difficult to judge whether you have troubles because there may be failures which cannot be detected only by thermography
Efforts towards the solution are required in the near future.
Motor Operated Valve Diagnostic Analysis System (MOVDAS) was innovated as a motor operated valve diagnostic equipment. MOVDAS can get data under normal operations. So it can evaluate integrity of motor operated valves.
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Approach to Condition Monitoring Techniques |
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Kouji HIGUMA (Toshiba Corporation) |
Toshiba has been developing condition monitoring techniques based on the following viewpoints;
1 ) Enhancement and laborsaving of field monitoring
2 ) Enhancement of condition monitoring
3 ) Streamlining maintenance management
Some of devices innovated for these purposes are;
- VIDIAS, a portable field-data-collecting device with PDA
- Ultrasonic vibrometer, which directly monitors shaft vibration with pulse-echo method from outside of a pomp casing
- Equipment record management TM system, which comprehensively displays and evaluates information on equipment aging by managing condition monitoring data, inspection records, and operation records overall.
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Status quo and Prospect of Structural Health Monitoring on Aviation Composite |
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Nobuo TAKEDA (University of Tokyo) |
Advanced composite material is indispensable for next-generation aerospace planes. To secure thier reliability, structural health monitoring techniques are very important. So, effective industry-university joint researches systems have to be developed.
Structurization of Carbon Fiber Reinforced Plastics (CFRP) and structural health monitoring have become key techniques in a whole aerospace structure system and further development is expected.
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Application and Theme of Condition Monitoring Techniques (CMT) |
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Hisakazu HIGASA (Asahi Kasei Engineering Corporation) |
In these days, many condition monitoring devices, such as vibration diagnostics, lubricant oil analysis, infrared thermography have been used in the field. Unfortunately, they don’t always sustain condition based maintenance (CBM).
This is because systems which support these devices are yet to be got up. In such cases, maintenance infrastructures themselves may not be built up yet. To solve this problem, rebuilding of maintenance system is urgent. As the first step of transition to CBM, equipment diagnosis, together with supportive systems should be taken into consideration.
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Thermography Techniques and its Application |
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Hirofumi YAMADA (Thermographers Co., Ltd) |
One of the most innovated condition monitoring techniques is infrared thermography, which makes temperatures in facilities and thermal energy transmission visible. This diagnostic technique surveys or infers conditions of targets.
Now, since infrared thermography uses noncontact diagnosis techniques, it has many uncertainties due to emissivity of targets, obstacles in optical path, etc. So it is quite difficult to automatize measurements and evaluations.
In the USA, qualification and certification of inspection personnel specific to infrared thermography (ASNT SNT-TC-1A Thermographer Level I/II/III) has been in practice, and their skills in measurement and evaluation are emphasized. The same certification and training program on infrared thermography is urgently necessary in Japan.
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Application Examples of Condition Monitoring on Ship Equipments |
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Takaaki HASHIMOTO (TRIBOTEX Co., Ltd) |
Ship equipment is expected to be in a good condition even though it is influenced by lubricating oil, fuel oil, ship structural vibration and ship roll motion due to weather conditions and so forth.
Condition Monitoring on propeller shafts, bearings at stern tubes can be applied under relatively good conditions. As for propeller shafts and stern tube bearing, overhaul inspections can be eliminated if certain conditions including lubricant oil analysis are met. Membership function may be applied for preventive maintenance.
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