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31 巻, 1 号
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山内 芳彦1993 年 31 巻 1 号 p. 3-11
発行日: 1993/01/25
公開日: 2010/08/05
ジャーナル フリーOil storage tanks are usually constructed directly on the earth foundations without anchors. In such a flat-bottom cylindrical tank subjected to seismic excitations, a part of the bottom plate adjacent to the shell will be lifted off the foundation due to overturning moment. Then, it results in a failure of the shell-to-bottom junction when fatigue cracks or defects exist at the toe of the fillet weld.
In this paper, the elastic-plastic fracture analysis code “FRACT-2D” based on the updated Lagrangian formulation of the finite deformation theory has been developed by the author for evaluating the nonlinear fracture parameter J-and J-integral of an axi-symmetric crack problem.
Applying this code to a crack assumed at the toe of the fillet weld joint of a 113, 000kl oil storage tank, the crack opening displacement (COD) and the crack-tip opening displacement (CTOD) are evaluated numerically under the uplift behavior of tank bottom. Then, the J-and J-integral are found to be path-independent except very close to the crack-tip in the region affected by plastic strain concentration.抄録全体を表示PDF形式でダウンロード (824K) -
三村 宏, 岡本 成夫1993 年 31 巻 1 号 p. 12-18
発行日: 1993/01/25
公開日: 2010/08/05
ジャーナル フリーThe effect of side grooves on ductile-brittle transition behaviour was studied in a mild steel by using COD test (for static crack initiation), V notched Charpy impact test (for reference) and press-notched Charpy test (for arrest of crack).
The results are as follows.
(1) Noticeable effect of side grooves on the critical COD was not recognized in the transition region.
(2) By depressing the plastic constraint transition, the side grooves raised the fracture appearance transition temperature of V notched Charpy test and the temperature where the critical COD increased steeply with temperature.
(3) By depressing formation of shear lip, the side grooves raised slightly the fracture appearance transition temperature of press-notched Charpy test.抄録全体を表示PDF形式でダウンロード (726K) -
第2報 高靱性50-55mm厚9%Ni鋼の特性町田 進, 石倉 則義, 久保 尚重, 片山 典彦, 村本 聖一, 萩原 行人, 有持 和茂1993 年 31 巻 1 号 p. 19-33
発行日: 1993/01/25
公開日: 2010/08/05
ジャーナル フリーIn the previous paper, it was showed that 40mm thick 9% Ni steels and their welded joints had sufficiently higher fracture toughness than the required toughness values evaluated under the postulated defect and the stress conditions. Actually, they have been applied to an LNG tank of 140, 000kl in capacity.
As the demand for larger LNG tanks is still increasing, heavier thick 9% Ni steels are required. This paper describes work carried out using brittle fracture initiation and arrest tests for 50mm and 55mm thick 9% Ni steels and their GTAW joints. Moreover, ductile fracture resistance (R curve) of the weld metal with 70% Ni alloy welding materials was also investigated, because a crack in the weld HAZ tends to deviate into the weld metal in case of 9% Ni steel.
It has been shown that the fracture initiation and arrest toughness of 50 and 55mm thick plates is satisfactory as compared with the 40mm thick plates and that the R curve of the GTAW weld metal is remarkably high. From these results and the safety assessments for applicability to LNG tanks, it has been concluded that these steel plates can be used with high safety margin.抄録全体を表示PDF形式でダウンロード (1362K) -
藤咲 衛1993 年 31 巻 1 号 p. 34-44
発行日: 1993/01/25
公開日: 2010/08/05
ジャーナル フリーAbout 75 per cent of oil refinary and petro chemical plants in Japan have been operated for over twenty years since they were constructed.
The phenomena of deterioration in chemical plants are increasing steadily, along with operation for this long period.
About 22 per cent of the causes of troubles on high perssure gas plants are closely related to maintaining equipment, such as deterioration, unsuitable repair work, and insufficient inspection.
The second largest cause of trouble is design error in equipment (14.7%).
Therefore, precise application of planed diagnosis techniques for the equipment is very useful to prevent the increase of troubles in chemical plants.
The typical kinds of failures in chemical plants change with operating period. For example, the instances of stress corrosion cracking decrease, while on the other hand, outside corrosion problems on towers, vessels and piping come to the surface.
Consequently, new developing inspection and diagnosis techniques will always be requested for maintenance of chemical plants. And recently, the results of inspection and diagnosis data for chemical plants are managed systematically using personal computers.抄録全体を表示PDF形式でダウンロード (3853K) -
長島 利行1993 年 31 巻 1 号 p. 45-52
発行日: 1993/01/25
公開日: 2010/08/05
ジャーナル フリーRecently, the needs of modification or new installation of reactors in desulfurization and hydrocracking pocesses are increased because of the great demand of naphtha, kerosine and gas oil instead of fuel oil, and the necessity of deep reduction of sulfur content in diesel oil and long duration of operation. In this connection, the state of the up-to-date design technology of high pressure desulfurization reactors in desulfurization and hydrocracking processes is introduced.抄録全体を表示PDF形式でダウンロード (721K)
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