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Showing 3 results for Fuzzy Fault Tree Analysis

Mehran Amiri, Abdollah Ardeshir, Ali Abbasi,
Volume 8, Issue 4 (12-2018)
Abstract

Introduction: Safety at workplaces is an important issue, and lack of effective and efficient safety management methods based on scientific studies could cost the construction industry. An effective accident investigation and root causes analysis could prevent the occurrence of incidents at minimum cost and time.
Material and Method: First, major accidents in road construction projects were identified by interview and literature reviewing techniques. Then, fault tree was drawn for each main risks. In the next step, in order to calculate occurrence probability and severity of each accident type, a questionnaire was designed and distributed among the participants. Fuzzy logic was employed in calculations, due to the existence of uncertainty in linguistic variables. Fuzzy Fault Tree Analysis (FFTA) was used for calculating the occurrence probability, and importance of each criterion was determined using Fuzzy Analytical Hierarchical Process (FAHP) to calculate the severity of each accident. Finally, risk factors for each accident type was calculated and the risks were ranked accordingly.
Result: Accidents related to crusher and asphalt plant, traffic accidents, heat exhaustion and lack of hygiene and hit by machinery were identified as the most important risks among the eleven investigated accident types.
Conclusion: The findings in this research and also implementing effective safety management techniques, could be helpful on reduction of the probability of accidents root causes and to mitigate related risks.
Sajad Bahrami, Ahad Sotoudeh, Naser Jamshidi, Mohammad Reza Elmi, Mohammad Saeid Poorsoleiman,
Volume 11, Issue 4 (12-2021)
Abstract

Introduction: Chemical industries often have risks for the environment and communities, due to the use of complex facilities and processes. Also, in the ammonia tanks, the probability of risk of explosion is high, owing to their specific characteristics. The aim of this study is to evaluate the risks of explosion scenario at the ammonia tank in the Kermanshah petrochemical complex
Material and Methods: To achieve the purpose of this study, the Fuzzy Fault Tree Analysis (FTA) method was used to estimate the probability of reliability in the basic events. In this study, after drawing Fault Tree for identifying basic events, the probability of basic events was estimated by means of expert’s elicitation, and the probability of minimal cut sets was computed through Boolean logic gates.
Results: According to the results, the probability of occurrence of the top event was obtained equal to 0/054997. In the minimal cut set prioritizing, the failing of pressure safety valves identified as the most effective factor in the top event occurrence, and afterward failing the control valves and human errors were identified.
Conclusion: This study indicates that, based on expert elicitation, a fuzzy error tree method can be used to assess the risk of various scenarios in the industry. Overall, in assessing the risk of the explosion scenario in the ammonia reservoir, it was found that some minor defects, and even human error, could be considered as a major contributor to the explosion.
 
Ehsan Ramezanifar, Kamran Gholamizadeh, Iraj Mohammadfam, Mostafa Mirzaei Aliabadi,
Volume 13, Issue 1 (3-2023)
Abstract

Introduction: Risk assessment is a scale for predicting reliability and can manage interactions between components and process variables. Moreover, the reliability of one component or barrier affects the overall risk of the system. Being one of the most critical safety barriers of the storage tank, the failures of Fixed Foam Systems (FFS) on demand can result in severe consequences. FFS, is of grave importance in decreasing the risks associated with fires and damages.
Material and Methods: This study aims to determine the probability of root causes related to FFS failure through Fuzzy Fault Tree Analysis (FFTA) to estimate system reliability. In conventional fault tree analysis, accurate data is usually used to assess the failure probability of basic events. Therefore, the introduced approaches were employed to quantify failure probabilities and uncertainty handling. Finally, system reliability was estimated according to the failure probability of the top event.
Results: The findings showed that 13 baseline events involved FFS performance. According to the results, failures of cable path and detection system (or resistance temperature detectors), set the activation switch (multi-position) incorrectly, and foam makers not continuously running are the three most critical basic events influencing the reliability of fixed foam systems. In addition, this paper estimated the system reliability at 0.8470.
Conclusion: The results showed that the FFTA could be used in matters such as reliability evaluation failure and risk assessment using experts’ judgment. This paper can also show the adaptation of the fuzzy approach to assess the failure probability of the basic event in the fault tree analysis (FTA).

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