Journal of High Pressure Institute of Japan
Online ISSN : 1347-9598
Print ISSN : 0387-0154
ISSN-L : 0387-0154
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Volume 61, Issue 6
Displaying 1-3 of 3 articles from this issue
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Original Paper
  • The Effect of Pre-Strain on the State of Hydrogen in CrMo and CrMoV Steels
    Yutaka TSUCHIDA, Misaho YAMAMURA, Tomohiko OMURA
    2023 Volume 61 Issue 6 Pages 258-270
    Published: 2023
    Released on J-STAGE: December 28, 2023
    DOIhttps://doi.org/10.11181/hpi.61.258
    JOURNAL FREE ACCESS
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    Peak separation on the TDA desorption curves was performed using the Gaussian distribution function. The amount of hydrogen at various traps was quantitatively evaluated for CrMo steel (JIS SCM435) and two types of CrMoV steel with different tempering temperatures. The pre-straining increases the density of dislocation, and causes the increment of the hydrogen trapped by dislocation (A1 hydrogen). The A1 hydrogen content becomes proportional to the amount of hydrogen trapped either by cementite (A0), dislocations (A1), grain boundaries (A2), and two kinds of V carbides (V1, V2), regardless the amount of pre-strain. Thus, the pre-strain affects non-explicitly on each amount of trapped hydrogen. It is also true for different hydrogen charging condition. The A1 hydrogen depends only on the dislocation density, meaning that the number density of dislocation is decisive. On the other hands, the amount of hydrogen at the other traps depends not on number densities but on the trapping efficiency of the trap sites. The vacancy, vacancy cluster and micro-void (B, C and D defects respectively) are formed by hydrogen charge after pre-straining, and behave differently from the A0, A1, A2, V1 and V2 traps; the amount of hydrogen trapped by these sites can be expressed as proportional to the product of the amount of pre-strain and the amount of A1 hydrogen for no pre-straining.
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  • Development and Application of Risk-Based Maintenance System for Dynamic and Functional Equipment to Establish Consistency with the Conventional Method for Static Equipment
    Akio FUJI, Shigemitsu KIHARA, Daisuke KOBAYASHI
    2023 Volume 61 Issue 6 Pages 271-277
    Published: 2023
    Released on J-STAGE: December 28, 2023
    DOIhttps://doi.org/10.11181/hpi.61.271
    JOURNAL FREE ACCESS
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    RBM (Risk-Based Maintenance) has been widely applied as a reasonable management system of maintenance and inspection planning for various facility or equipment. Regarding the RBM, the risk assessment was intended as practical use for static components such as many pressure vessels and piping system etc. However, various dynamic and functional component composed of a factory have been applied a different maintenance system.
    In this study, RBM estimation method based on bathtub diagram and Weibull distribution concept is developed. It is composed the basic accumulated failure probability diagram, adjustment of scale parameter η and inspection confidence factor. As results, the RBM suggests the possibility of reasonable and comprehensive inspection and maintenance system.
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