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Volume 52 (2014)
- Issue 6 Pages 306-
- Issue 5 Pages 238-
- Issue 4 Pages 172-
- Issue 3 Pages 100-
- Issue 2 Pages 53-
- Issue 1 Pages 4-
Predecessor
Volume 52, Issue 2
Displaying 1-4 of 4 articles from this issue
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Original Paper
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Takuyo KAIDA, Yoichi ISHIZAKI, Satoshi OKAJIMA2014 Volume 52 Issue 2 Pages 53-63
Published: March 25, 2014
Released on J-STAGE: April 17, 2014
JOURNAL FREE ACCESSProbabilistic approach for Fitness-For-Service (FFS) assessment of pressure equipment in petroleum and petrochemical plant helps to quantify the safety margin and rationalize the assessment. As for local metal loss assessment, several studies have been made on reliability analysis of the damaged equipment by use of limit state function, denoted by deterministic FFS model in published standard. Stochastic properties of random variables are needed in the reliability analysis. Remaining thickness of the pressure equipment is one of the important variables in limit state function for metal loss assessment. The thickness readings on a prescribed grid, which characterize the remaining thickness and size of the region of metal loss, might be varied by each inspector. There has been, however, no studies on stochastic properties of thickness readings for the local metal loss assessment. In this study, the stochastic properties of thickness readings were investigated by analyzing of the results of Round-Robin test. The cause of variation of thickness readings was clarified for the purpose of either protection of failure by pressure or that of leakage. The results of investigation indicated that standard deviation of thickness readings in the region of metal loss was more than that of thickness away from metal loss. Finally, the reliability of pressure equipment with local metal loss was analyzed using stochastic properties.View full abstractDownload PDF (611K) -
Tomoyuki KURIHARA, Takuyo KAIDA, Satoshi OKAJIMA2014 Volume 52 Issue 2 Pages 64-71
Published: March 25, 2014
Released on J-STAGE: April 17, 2014
JOURNAL FREE ACCESSIn Fitness-For-Service (FFS) assessment of pressure equipment, high reliability is needed in petroleum and petrochemical plant. Future Corrosion Allowance (FCA) is one of the most important factors in the metal loss assessment of FFS because it decides predicted value of the thickness during service periods. For the evaluation of FCA, the accurate corrosion rate from actual thinning data is needed and it is necessary to make a consideration of their variability of the thinning phenomena.
In this study, the measured thickness data of the oil piping in the actual plant are collected and statistically analyzed as corrosion rate data which are classified by the operation condition. By the analysis, the probabilistic properties of corrosion rate are clarified in this piping system. Especially it is cleared that the corrosion rate of the air injection part is higher than that of the no air injection part. And the reliabilities of the protection of the failure by pressure and their change are quantitatively evaluated from the probabilistic properties of corrosion rate. From this case study, the procedure of FCA evaluation of FFS assessment was established and it's clear that the statistical analysis by the feature of thinning phenomena is important for accurate evaluation of corrosion data.View full abstractDownload PDF (412K) -
Atsushi YAMAGUCHI, Nobuyuki YOSHIDA, Takuyo KAIDA2014 Volume 52 Issue 2 Pages 72-80
Published: March 25, 2014
Released on J-STAGE: April 17, 2014
JOURNAL FREE ACCESSPressure equipment used in the petroleum and petrochemical industries develop locally thinned areas, which are caused by damage related to aging. In order to stably operate such pressure equipment, proper evaluation of the integrity of the pressure equipment with locally thinned areas is very important. The American Petroleum Institute (API) and the American Society of Mechanical Engineers (ASME) recommend Fitness-For-Service (FFS) as a method of integrity evaluation. In the present study,
complicated locally thinned areas are generated in nine test pipes using a corrosive liquid, and the test pipes are then burst in burst tests. The estimated burst pressure,
which is calculated based on the assessment of local metal loss and through finite element analysis (FEA) based on API⁄ASME FFS-1, is compared with experimentally obtained burst pressures in order to validate the integrity evaluation by FFS. The estimated burst pressures agree well with the experimental results, except for test pipes with locally deep areas of metal loss. Moreover, the burst pressure estimated by FEA is lower than that obtained through the assessment of local metal loss. Therefore, FFS is demonstrated to be useful in the integrity evaluation of pipes with complicated locally thinned areas.View full abstractDownload PDF (1282K) -
Runze ZHOU, Ikuo KOJIMA, Hirokazu TSUJI2014 Volume 52 Issue 2 Pages 81-90
Published: March 25, 2014
Released on J-STAGE: April 17, 2014
JOURNAL FREE ACCESSFitness-For-Service (FFS) assessments are quantitative engineering evaluations that perform to demonstrate the integrity of an in-service component that may contain a flaw or damage. It can be used to make run-repair-replace decisions to help determine if pressured equipment containing flaw that have been identified by inspection can continue to operate safety for some period of time.
This paper provides a FFS assessment method on carbon steel pipe which contained a LTA (Local Thin Area) against seismic load by FEM (Finite Element Method) analysis. Abaqus Ver. 6. 10, which provides the combined isotropic⁄kinematic hardening model, is used to simulate the LTA contained carbon steel pipe against seismic load. Material parameters in the hardening model are identified by a symmetric strain cycle experiment based on ASTM E606. Isotropic hardening component is introduced by specifying the equivalent stress defining the size of the yield surface, as a tabular function of the equivalent plastic strain. Kinematic hardening component is obtained from the stabilized cycle of a specimen that is subjected to symmetric stain cycles.
The authors introduced the way how to calibrate the material parameters of combined isotropic⁄kinematic hardening model. Then the authors calculated up to 200 cycles on carbon steel pipe which contained a Local Thin Area against seismic load at 300 degrees centigrade. The results comparison between FEM analysis and experiment shows that stress-strain hysteresis loop tendency and number of cycles to failure are predicted accurately. Safety margin of ratcheting assessment also was discussed in this paper.View full abstractDownload PDF (622K)
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