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Title: Dynamic failure assessment of an ammonia storage unit: A case study
Authors: Roy A.
Srivastava P.
Sinha, Shishir N.
Published in: Process Safety and Environmental Protection
Abstract: Chemical Process Industries usually contain a diverse inventory of hazardous chemicals and complex systems required to perform process operations such as storage, separation, reaction, compression etc. The complex interactions between the equipment make them vulnerable to catastrophic accidents. Risk and failure assessment provide engineers with an intuitive tool for decision making in the operation of such plants. Abnormal events and nearmiss situations occur regularly during the operation of a system. Accident Sequence Precursors (ASP) can be used to demonstrate the real-time operating condition of a plant. Dynamic Failure Assessment (DFA) methodology is based on Bayesian statistical methods incorporates ASP data to revise the generic failure probabilities of the systems during its operational lifetime. In this paper, DFA methodology is applied on an ammonia storage unit in a specialized chemical industry. Ammonia is stored in cold storage tanks as liquefied gas at atmospheric pressure. These tanks are susceptible to failures due to various abnormal conditions arising due process failures. Tank failures due to three such abnormal conditions are considered. Variation of the failure probability of the safety systems is demonstrated. The authors use ASP data collected from plant specific sources and safety expert judgement. The failure probabilities of some safety systems concerned show considerable deviation from the generic values. The method helps to locate the components which have undergone more degradation over the period and hence must be paid attention to. In addition, a Bayesian predictive model has been used to predict the number of abnormal events in the next time interval. The user-friendly and intuitive nature of the tool makes it appropriate for application in safety assessment reports in process industries. © 2014 The Institution of Chemical Engineers.
Citation: Process Safety and Environmental Protection (2015), 94(C): 385-401
Issue Date: 2015
Publisher: Institution of Chemical Engineers
Keywords: Abnormal event
Accident sequence precursor
Ammonia tank failure
Bayesian theory
Dynamic failure assessment
ISSN: 9575820
Author Scopus IDs: 7402704332
Author Affiliations: Roy, A., Department of Chemical Engineering, Indian Institute of Technology, Roorkee, Roorkee, 247667, India
Srivastava, P., Department of CoEDMM, Indian Institute of Technology, Roorkee, Roorkee, 247667, India
Sinha, S., Department of Chemical Engineering, Indian Institute of Technology, Roorkee, Roorkee, 247667, India
Funding Details: This study was supported by Indian Institute of Technology Roorkee , Roorkee INDIA and MHRD INDIA.
Corresponding Author: Sinha, S.; Department of Chemical Engineering, Indian Institute of Technology, RoorkeeIndia; email:
Appears in Collections:Journal Publications [CH]

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