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Predecessor
Volume 46, Issue 1
Displaying 1-4 of 4 articles from this issue
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Original Paper
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Haruki NISHI, Minoru YAMADA, Shinsaku ZAMA, Ken HATAYAMA, Kazuyoshi SE ...2008 Volume 46 Issue 1 Pages 4-17
Published: 2008
Released on J-STAGE: February 25, 2008
JOURNAL FREE ACCESSThe 2003 Tokachi-oki Earthquake (M8. 0) caused severe damage to oil storage tanks at Tomakomai, igniting fires and sinking floating roofs. The cause of this damage was the liquid sloshing of oil storage tanks excited by long-period strong ground motion. After the earthquake, the technical standard of the Fire Service Act regarding the sloshing of floating roof tanks was revised in 2005 and a certain number of floating roofs are scheduled to be reinforced before 2017 if necessary in order to prevent similar damage to large oil storage tanks as a result of future earthquakes.
However, thorough verification of the dynamic behavior of a floating roof due to liquid sloshing is difficult using an actual oil storage tank, especially when the non-linear sloshing is remarkable. There have been few studies on the formulation of the non-linear sloshing of the actual floating roof. The non-linearity is a foundation of the technical standard for the strength evaluation in the Fire Service Act. Therefore, the adequacy of the formulations of the large-wave-height sloshing with a floating roof must be confirmed experimentally using an actual oil storage tank.
In the present study, we conduct sloshing experiments by directly vibrating the floating roof of an actual 38-m-diameter tank. The goal is to examine the formulations of the non-linear liquid sloshing behavior for a floating roof and the formulations of the strain produced at the pontoon of the floating roof.
Based on the experimental results, we concluded that the formulations of the non-linear liquid sloshing behavior and the strain at the pontoon are adequate. The viscous damping factor of the liquid sloshing with a single-deck type floating roof is less than 0. 5% when the sloshing height is considerable.View full abstractDownload PDF (607K) -
The report of the risk analysis for corrosion in bottom plates of oil storage tanks by using continuous thickness measurement dataKoichi TAMURA, Hiroyuki HAGA, Yoshio TSUJI, Shigeo KITSUKAWA, Naoya KA ...2008 Volume 46 Issue 1 Pages 18-25
Published: 2008
Released on J-STAGE: February 25, 2008
JOURNAL FREE ACCESSThe statistical analysis of back side metal loss on tank bottom plates was carried out by using the dataset measured with ultrasonic continuously thickness measurement devices. The relationship between the maximum depth of metal loss and the exceedance cumulative probability in log-log plot showed linear dependence on large metal loss region. The slope of this relationship indicated the degree of local corrosion generated in oil tank bottom plates. In this study, use of the relationship to assess the corrosion risk of oil tank bottom plates was proposed. The corrosion risk parameter derived from the relationship correlated with the actual corrosion rate obtained by the continuous thickness measurement dataset.
For the practical point of views, authors showed the corrosion risk parameter can predict the maximum depth of metal loss, and it was effective information to maintain oil tank bottom plates safely. Furthermore, through the analysis with various dataset, the characteristic of corrosion generated in large scale tank bottom plates was different with that of small scale tank bottom plates.View full abstractDownload PDF (2488K) -
Hideyuki NAKAMURA, Takahiro ARAKAWA, Kazuyoshi SEKINE, Naoya KASAI, Mo ...2008 Volume 46 Issue 1 Pages 26-31
Published: 2008
Released on J-STAGE: February 25, 2008
JOURNAL FREE ACCESSRecently, the corrosion evaluation technology of the tank floors by the acoustic emission (AE) method has been put to practical use in Japan. However, sometime the evaluation of the corrosion with the AE method brings the judgments of overprotection by the influence of various noises, and this is a factor to decrease the accuracy of this evaluation technology. In this research, we examined the identification and the removal methods of the drop noise that are generated by the coagulated oil dropping in the surface of the stored oil. We specified the noise source with the three dimension source location (3D source location) , verified a feature of the waveform of the drop noise, and confirmed the effects of some removal methods for the drop noises. As a result, the noise of app. 90% was able to be removed by a conventional method with the guard sensors, and a great effect of this method was confirmed. However, it was confirmed that the drop noise was not able to be removed completely by the guard sensors when the noises reached the sensors after it had reflected to the tank floor or the shroud. The tank was not able to be judged to be no damage from the data with the guard sensors though it was confirmed that there was no corrosion in the overhaul inspection. On the other hand, the noise of 99% was able to be removed in the method of the noise removing with the 3D source location, and it was confirmed that this method was effective to the removal of the drop noise.View full abstractDownload PDF (205K)
Review
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Part 1 Status of Oil Stock Piling in Japan and Overview of Strategic Maintenance System for Oil Storage TanksTsukasa MITSUTA, Hiroaki KOBAYAKAWA, Takahide SAKAGAMI, Takayasu TAHAR ...2008 Volume 46 Issue 1 Pages 32-38
Published: 2008
Released on J-STAGE: February 25, 2008
JOURNAL FREE ACCESSOil stock piling makes one of the most important functions of our country in order to maintain stable national economy basis in recent years which show drastic changes in trade balance of worldwide energy resources.
This paper presents recent status of oil stock pilings in Japan. And overview of strategic maintenance system for oil storage tanks in order to keep safe operation against long term material degradation an⁄or disaster such as corrosion and earthquake, which have been developed by the project team named TSM Committee in High Pressure Institute of Japan, HPI was assigned by the Japan Oil Gas and Metals National Corporation, JOGMEC.
This report describes results of activities of TSM Committee in five Parts respectively;
Part 1 Status of Oil Stock Piling in Japan and Overview of Strategic Maintenance System for Oil Storage Tank
Part 2 Risk Based Maintenance for Oil Storage Tanks
Part 3 Fitness-For-Service Assessment for Oil Storage Tanks
Part 4 Nondestructive Examination for Oil Storage Tanks
Part 5 Survey of Overseas Tank Maintenance Regulations and StandardsView full abstractDownload PDF (1364K)
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