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Konosu S.,Ibaraki University | Ogasawara K.,Mitsui Engineering and Shipbuilding Co. | Oyamada K.,High Pressure Gas Safety Institute of Japan
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2015

This paper develops a procedure for plastic collapse assessment of vessel (run pipe) - nozzle (branch pipe) intersections with an arbitrarily positioned local thin area (LTA) under different loading conditions, namely internal pressure, external moment on a nozzle applied along various directions with respect to the vessel main axis, and pure bending moment on a vessel. Although simplified procedures for plastic collapse assessment based on the p-M (internal pressure ratio and external bending moment ratio) diagram method have been previously proposed for straight cylindrical vessels and pipe bends with an LTA, very few studies have dealt with the determination of plastic collapse load for an LTA in the critical region of intersecting vessels subjected to internal pressure and external moment loading. This is likely due to the complexity of the stresses caused by the applied loads in the critical region, which arises from geometric discontinuities. In this paper, simple and empirical formulae for predicting conservative plastic collapse loads for an LTA in the critical region of the intersecting vessels are proposed based on the analytical results of stresses at defect-free vesselnozzle intersections by using linear finite element analysis (FEA). Localized elastic stress retardation factors are taken into account in the evaluation by the results of a non-linear FEA. Consequently, a p-M diagram method is developed for application to vessel-nozzle intersections with an LTA. © Copyright 2015 by ASME.


Oka Y.,Yokohama National University | Yoshida T.,Yokohama National University | Kondo T.,High Pressure Gas Safety Institute of Japan | Ito S.,Japan National Institute of Advanced Industrial Science and Technology | Katoh K.,Fukuoka University
Journal of Thermal Analysis and Calorimetry | Year: 2010

In Japan, tert-butyl mercaptan (TBM) is mainly employed as an odorant of LPG. However, the sulfur component in TBM gives the adverse effect for environment and human body and/or has a negative impact on reforming catalyst of fuel cell and other types of cogeneration systems. In this way, the development of sulfur-free odorant is expected. This study focuses on the thermal stability and combustibility of 2-hexyne, 1-pentyne, n-butyl isocyanide (BIC), and ethyl isocyanide (EIC) that is expected as the candidate odorants. As the result of DSC measurement, the comparison of TDSC indicated that 2-hexyne and 1-pentyne are more thermally stable than BIC and EIC. However, in 2-hexyne and 1-pentyne, the slight exothermic peaks were observed at lower temperature region before those main exothermic peaks. In 2-hexyne, copper or aluminum increased the heat amount of that slight exothermic peak observed before main peak. In 1-pentyne with zinc, TDSC was approximately decreased to 279 °C from 337 °C of 1-pentyne alone. As the results of ARC measurement, in the presence of oxygen, the exothermic heat of 2-hexyne and 1-pentyne was observed at approximately 50-100 °C. This heat release may be corresponding to the slight heat release observed by DSC, and it thought to be results from the reaction with atmospheric oxygen. In this way, for the practical application of 2-hexyne and 1-pentyne as odorants, it is important to suppress the invasion of oxygen in the cylinder to low as much as possible in respect of the storage of the candidate odorant. As a result of thermal equilibrium calculation, even if either candidate odorant is added at about 100 ppm, there is little influence on propane combustibility from the adiabatic flame temperature, species of combustion gas and their yields. © Akadémiai Kiadó, Budapest, Hungary 2009.


Ohno T.,Aoyama Gakuin University | Kobayashi N.,Aoyama Gakuin University | Oyamada K.,High Pressure Gas Safety Institute of Japan
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2015

A significant fire and explosion accident on spherical storage tanks for Liquefied Petroleum Gas (LPG) at Chiba prefecture in Japan were occurred due to the strong ground motion of the 2011 Great East Japan Earthquake. The braces made of steel pipe for supporting columns of a spherical tank, which was filled with water for purging air at that time, were broken by the strong seismic inertia force. Then, buckling of columns was occurred by the aftershock. To clarify the failure mechanism of the pipe braces of its supporting frame of a spherical tank, the elastic and elastic-plastic finite element analysis (FEA) was performed. From FEA results, the failure mechanism of the pipe brace was revealed as follows; (1) high stress was generated in the intersection of long and short braces due to the structural discontinuities, (2) the generated high stress was a trigger of the failure initiation of the damage of the supporting frame, (3) the breakage of the intersection of the long and short braces of the supporting frame was caused overturn of the spherical tank at the aftershock of predominant earthquake. In this paper, the fracture mechanism of the spherical storage tank was clarified for prevention of the same type accidents, and the effective reinforcement method of pipe braces of spherical tanks was proposed for securing safety. Copyright © 2015 by ASME.


Oyamada K.,High Pressure Gas Safety Institute of Japan | Konosu S.,Ibaraki University | Ohno T.,High Pressure Gas Safety Institute of Japan
Nuclear Engineering and Design | Year: 2012

Pipe bends are common elements in piping systems such as power or process piping, and local thinning typically occurs on pipe bends due to erosion and/or corrosion. Therefore, it is important to establish the plastic collapse condition for pipe bends having a local thin area (LTA) under combined internal pressure and external bending moment. In this paper, a simplified plastic collapse assessment procedure in the p-M (internal pressure ratio and external bending moment ratio) diagram method for pipe bends with a local thin area simultaneously subjected to internal pressure, p, and external in-plane bending moment, M, due to earthquake, etc.; is proposed, which is based on the reference stresses derived from the Tresca theory under a three axes condition. The plastic collapse loads derived from the proposed p-M diagram method are ascertained by comparing with the results of experimental testing with full-scale pipe bends and those of FEA for the same sized pipe bends with an LTA having various dimensions as well. © 2012 Elsevier B.V. All rights reserved.


Oyamada K.,Ibaraki University | Konosu S.,Ibaraki University | Ohno T.,High Pressure Gas Safety Institute of Japan
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

Remaining Strength Factor (RSF) approach in Part 5 of API 579-1/ASME FFS-1 is an assessment method for a cylindrical component with a local metal loss based on surface correction factors. Also, reference stress solutions that are applied in the Failure Assessment Diagram (FAD) method for a cylindrical component with a crack-like flaw are provided in Annex D using surface correction factors. In the p-M diagram method that has been recently developed, reference stress solution for local metal loss evaluation in a cylindrical component is derived using bulging factors, which are similar but not identical to the surface correction factors used in API 579-1/ASME FFS-1. This paper describes the results of a comparative study among the RSF approach, reference stress solutions for the FAD method, and the p-M diagram method, in terms of plastic collapse evaluation of a cylindrical component. These results were compared with the FEA and experimental results to confirm how those estimated stresses could be validated. The results of the study also contain proposals for prospective modifications of API 579-1/ASME FFS-1. Copyright © 2009 by ASME.


Oyamada K.,High Pressure Gas Safety Institute of Japan | Miyashita T.,High Pressure Gas Safety Institute of Japan | Konosu S.,Ibaraki University | Ohno T.,High Pressure Gas Safety Institute of Japan | Suzuki H.,High Pressure Gas Safety Institute of Japan
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2015

There are numerous cases in which a volumetric flaw such as a local thin area (LTA) is found in pressure equipment such as vessels, piping, tanks, and so on. Sometimes it is found near vessel and nozzle intersection. A fitness for service (FFS) rule of such cases was desired, because plastic collapse assessment of LTA near vessel and nozzle intersection usually needed to conduct by numerical analysis such as FEA. Recently, an FFS assessment rule of plastic collapse assessment of LTA near vessel (run-pipe) and nozzle (branch pipe) intersection subjected to internal pressure and external loadings has been developed and proposed by one of authors of this paper. In this paper, the proposed plastic collapse assessment rule was verified with results of experiments and FEA for cylindrical vessels with an LTA near vessel and nozzle intersections subjected to internal pressure and external loadings. © Copyright 2015 by ASME.


Oyamada K.,High Pressure Gas Safety Institute of Japan | Konosu S.,Ibaraki University | Ohno T.,High Pressure Gas Safety Institute of Japan
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2012

Pipe bends are common elements in piping system such as power or process piping, and local thinning are typically occurred on pipe bends due to erosion or corrosion. Therefore, it is important to establish the plastic collapse condition for pipe bends having a local thin area (LTA) under combined internal pressure and external bending moment. In this paper, a simplified plastic collapse assessment procedure in p-M (internal pressure ratio and external bending moment ratio) diagram method for pipe bends with a local thin area simultaneously subjected to internal pressure, p, and external out-of-plane bending moment, M, due to earthquake, etc., is proposed, which is derived from the reference stress. In this paper, only cases of that an LTA is located in the crown of pipe bends are considered. The plastic collapse loads derived from the p-M diagram method are compared with the results of both experiments and FEA for pipe bends of the same size with various configurations of an LTA. Copyright © 2012 by ASME.


Hatayama K.,High Pressure Gas Safety Institute of Japan | Matsumoto K.,High Pressure Gas Safety Institute of Japan | Oikawa H.,High Pressure Gas Safety Institute of Japan | Ichikawa M.,High Pressure Gas Safety Institute of Japan
Perspectives on Process Safety from Around the World 2016 - Topical Conference at the 2016 AIChE Spring Meeting and 12th Global Congress on Process Safety | Year: 2016

If handled incorrectly, the high pressure gas used widely in industries can cause damage not only to the plant in which it is being handled, but also to the surrounding area. For this reason, in accordance with the High Pressure Gas Safety Act, any compressed gas greater than or equal to 1 MPaG (145 psi) (0.2 MPaG (29 psig) for compressed acetylene gas and liquefied gas) is classed as "High Pressure Gas" in Japan, and its production, storage, and sale are strictly regulated. The act mainly consists of: "Conformity of facilities and equipment with technical standards" "Preparation of documents related to safe administration" and "Allocation of qualified personnel". Recently, the improvements and promotions of risk assessments especially non steady state, employee training and use of new technologies have been studied in relation to the High Pressure Gas Safety Act.


Oyamada K.,High Pressure Gas Safety Institute of Japan | Konosu S.,Ibaraki University | Miyata H.,Ibaraki University | Ohno T.,High Pressure Gas Safety Institute of Japan
Strength, Fracture and Complexity | Year: 2010

There are several Fitness-For-Service (FFS) standards with evaluation rules in terms of plastic collapse for pressure equipment possessing a local metal loss simultaneously subjected to internal pressure and bending moment. The authors have already reported the results of a comparative study of FFS rules, including the remaining strength factor approach in API 579-1/ASME FFS-1 and the p-M (pressure and moment) diagram method, which pointed out that there could be significant differences in allowable flaw sizes. In this paper, acceptance criterion for plastic collapse assessment on local metal loss at high temperatures is proposed with taking into account the effect of decreasing yield strength of material at high temperatures, such as 350°C. The allowable flaw depth at high temperatures derived from API 579-1/ASME FFS-1 is larger than that obtained by the p-M diagram method. However, it is verified by finite element analysis that the allowable flaw size of the p-M diagram method is set on the stress state of general yielding near a local metal loss area if safety factor is not considered and it is possible to evade ratcheting due to cyclic bending moment in service such as that caused by earthquake if the proposed acceptance criterion is used. © 2010 IOS Press and the authors. All rights reserved.


Kasai N.,Yokohama National University | Tsuchiya C.,Yokohama National University | Fukuda T.,Nagaoka University of Technology | Sekine K.,Yokohama National University | And 2 more authors.
NDT and E International | Year: 2011

The present study investigated the ability of a system using a carbon infrared emitter (CIE) and an infrared (IR) camera to detect a combustible gas, propane. The CIE transmitted infrared at wavelengths ranging from 1 to 5 μm, and the infrared absorption band of propane gas (3.37 μm) was obtained using a bandpass filter to remove other infrared wavelengths. The intensity of infrared radiation passing through the propane gas decreased as a result of infrared absorption. A clear, real-time image of the gas leak was also obtained using this system. Furthermore, a hazard evaluation of the leakage propane gas was made from a correlation between infrared intensity and the concentrationpathlength product. © 2010 Elsevier Ltd. All rights reserved.

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