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Volume 33 (1995)
- Issue 6 Pages 286-
- Issue 5 Pages 230-
- Issue 4 Pages 174-
- Issue 3 Pages 116-
- Issue 2 Pages 50-
- Issue 1 Pages 4-
Predecessor
Volume 33, Issue 3
Displaying 1-6 of 6 articles from this issue
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Yasuo OTOGURO, Isao ITOH, Kohji AKABA, Hidesato MABUCHI, Kazushi HAMAD ...1995 Volume 33 Issue 3 Pages 116-126
Published: May 25, 1995
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSMicrostructures and creep rupture properties of extra low carbon 7-11Cr-4 Mo-(Ni) steels were investigated to evaluate the effect of intermetallic compounds on enhancement of high temperature strength.
The following results were obtained.
1) Precipitates were a small amount of carbides, and Laves phase, Fe2Mo.
2) Initial hardness was higher with increasing Ni content but age hardening was observed only in steels without Ni.
3) Structures of 9Cr-4Mo and 7Cr-4Mo steels were ferrite but Ni addition increased amount of martensite.
4) Creep rupture strength of martensitic steels was higher than that of ferritic steels. Fine Fe2Mo in the former steels contributed to enhanced rupture strength.
5) Creep rupture strength of heat affected zone (HAZ) was markedly lower than that of base metal for martensitic steels. On the other hand, the difference between them was remarkably small for ferritic steels.
6) Creep rupture strength in transverse direction was markedly lower than that in longitudinal direction for ferritic steels.
7) Though steels produced by a powder sintering and rolling process had finer grain than those produced by an ordinary hot rolling process, rupture strength was almost same or that of the former was slightly higher.View full abstractDownload PDF (8926K) -
Takashi KAGAMI1995 Volume 33 Issue 3 Pages 127-134
Published: May 25, 1995
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSAn explosion and subsequent fire took place at Fuji Oil Sodegaura Refinery on October 1992, resulting 10 deaths and 7 injured.
The MITI's investigation report states that main cause of the accident is considered to be the thermal stresses generatd by the difference in thermal expansion between the internal parts (austenitic stainless steel) and the channel barrel (ferritic steel).
In this paper, following three new design approaches are presented in order to reduce the thermal stress which might be generated by the thermal expansion difference between internal parts and channel barrel.
(1) Application of the ferritic stainless steel to the internal parts which have a same amount of the coefficcient of thermal expansion to the channel barrel material.
(2) Application of the spiral wound gasket that is capable to adsorb the thermal stress generated by the thermal expansion difference.
(3) Application of the both ferritic stainless steel internal parts and spiral wound gasket under combination.View full abstractDownload PDF (810K) -
Takahiro KUBO, Eiji SUGIE, Yutaka CHIDA, Kozo IKEZOE1995 Volume 33 Issue 3 Pages 135-146
Published: May 25, 1995
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThough the stress relief (SR) heat treatment which intends to reduce welding residual stress has been required to pressure vessels made with steel plates whose thickness is greater than the specified one, it is impossible when the pressure vessels become very large. The present research was done to study the applicability of constructing method without SR heat treatment to the tanks for LPG carriers. The material was 720N/mm2 class high strength steel plate whose thickness varied between 40mm and 60mm. The welded joints were made by submerged arc welding and MAG welding. Their fracture toughness were obtained by Charpy, CTOD and surface notched, cross joint wide plate tensile tests.
The SR heat treatment did not affect the toughness of the heat affected zone of steel plates, but that of weld metal. The critical CTOD value of each welded joint which was made without SR heat treatment was greater than that which is required to prevent brittle fracture initiation from the 5mm deep and 30mm long surface defect. Comparing the allowable stress for shell of cylindrical pressure tank to the fracture stress estimated from Charpy absorbed energy, it was clear that the 60mm thick plate welded joint had the resistance to brittle fracture at the temperature of not lower than -40°C. The present study clearly proved that the resistance to brittle fracture initiation of tanks for LPG carrier is not reduced in case the tank is constructed using 720N/mm2 class high strength steel plates without SR heat treatment.View full abstractDownload PDF (1192K) -
Kazuyoshi SEKINE, Taiichiro IZUMI, Kunio YOSHIKAWA1995 Volume 33 Issue 3 Pages 147-153
Published: May 25, 1995
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSIn the previous paper (J. HPI of Japan, vol. 32, p. 240 (1994)), we have shown that the risk curves, in which the exceedance cumulative frequencies in accidents are plotted on log-log scale as a function of their magnitude of damages, give significant insight into characterizing risk of hazardous events. The first problem for risk characterization using such risk curves is to clarify what type of mathematical expression can describe the entire distribution of risk curves. The second problem is on the statistical treatment for uncertainty in data of large-scale events having a very low frequency which is represented in the tail of risk curves. This paper is concerned with both these problems.
By extension of fractal-characterizing for stochastic occurrence of hazardous events depending on their magnitude of consequence, the Pareto type distribution function with a location parameter γ, which can be expressed by F(h)∝(h+γ)-D, is proposed as a mathematical form describing whole risk curves. From the result that the risk curve has the Pareto type form, it has been reduced by the extreme-statistical analysis that the extreme events of large-scale accident follow to the second type asymptotic distribution function of the largest values, which is called the Frechet distribution.
The adequacy of the proposed forms concerning risk curves and describing the statistical feature on large scale accidents in the tail of them were confirmed by Pareto plots on log-log paper and by Frechet plots on Weibull probability paper, respectively, using a lot of collected accident data.View full abstractDownload PDF (849K) -
Shozo YANAGIDA, Akira SUZUKI, Makoto AKATSU1995 Volume 33 Issue 3 Pages 154-162
Published: May 25, 1995
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSJIS B 8243, Quick Closure for Pressure Vessels, encompasses constructions of several types. Design calculation formulas for integral clamp type. devided clamp type, clamp type with ratch, sectional ring type and rectangular yoke frame type have been already introduced in Part 1 to Part 5.
In Part 6, the last part of this series of article, obround yoke frame type is explained for its strength calculation.
As this type of closure has no sharp discontinuity in configuration, it has suitable to ultra-high pressure services. This type of device is apt to become heavy due to the thick yokes when the device is large in capacity, while the yokes are easily fixable and removable by manual when smaller in capacity.
Finally, examples of accidents of various types of quick closures actually occured in industrial services and safety devices to prevent such accidents are introduced also.View full abstractDownload PDF (703K) -
Activity of J-ETD Committee and Results of Questionnaire SurveyTakayasu TAHARA, Masanori MINE, Teruyoshi UDOGUCHI1995 Volume 33 Issue 3 Pages 163-169
Published: May 25, 1995
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe Elevated Temperature Design Committee, chaired by Prof. Yasuhide Asada, was started in June, 1992 to establish Simplified Analytical Procedures for Design and Strucutural Serviceability Assessment for Non-nuclear Pressure Vessels based on high temperature design method of fast breeder reactor in Japan, “Monjyu”, and also to exchange information useful for both PVRC-ETD and JRVRC-ETD (J-ETD). J-ETD consists of three sub-committes, Analytical Method, Codes and Standards and Mechanical Properies, and 24 members.
This interim report summarizes studies of mechanical properties for elevated temperature design of pressure vessels by Sub-committee on Mechanical Properties.View full abstractDownload PDF (741K)
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