Reliability analysis of safety-instrumented systems operated in high-demand mode

Wang, Yukun; Rausand, Marvin

doi:10.1016/j.jlp.2014.09.007

Cited by 26 publications

(10 citation statements)

References 10 publications

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“…And then, for different results of PFD and PFH, safety barriers can be located at different integrity levels (SILs), from the loose SIL 1 to the strictest SIL 4. These measures are widely used, and they are calculated always on the basis of some basic assumptions (Jin and Rausand 2014, Wang and Rausand 2014, Rausand 2014, including: (1) each failure is assumed to occur at a constant rate (i.e. exponential distributed failures); and (2) the channels in a redundant structures are identical and independent.…”

Section: Measures Of Technological Barriersmentioning

confidence: 99%

Prognostic and health management for safety barriers in infrastructures: Opportunities and challenges

Zhang¹,

Liu²,

Barros³

et al. 2018

Safety and Reliability – Safe Societies in a Changing World

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Different types of safety barriers are deployed in many infrastructures to reduce the occurrences of hazards, and protect people, environment and other assets in case the unexpected events have occurred and the capacity of these barriers against hazards can be weakened by degradations or the failures related to changes over time. It is natural to adapt the approaches of Prognostic and Health Management (PHM) to monitor the conditions and measurable parameters of safety barriers, and predict their future performance by assessing the extent of degradations. This study aims to identify the uniqueness and possible challenges when implementing PHM on safety barriers. Definitions and classifications of safety barriers will be discussed with considering their installation environment in infrastructures, in order to reveal what kind of characteristics of barriers can lead to higher demand on prognosis and heath monitoring. Another objective of this paper is to review the qualitative and quantitative measures for the capacity and performance of safety barriers, and to explore the possible methods and research gaps in the assessments for different PHM strategies, taking account their effects on safety barriers, and effects on the infrastructures being protected by the barriers.

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Section: Measures Of Technological Barriersmentioning

confidence: 99%

Prognostic and health management for safety barriers in infrastructures: Opportunities and challenges

Zhang¹,

Liu²,

Barros³

et al. 2018

Safety and Reliability – Safe Societies in a Changing World

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“…Based on these analyses, the safety improvement execution steps shown in Figure 1 are presented to determine the necessity of the safety systems. Increased reliability of the measurement control systems can lead to a reduction and prevention of major industrial accidents caused by the malfunction of the control systems and improve the safety of the chemical processes in plants [5]. An ideal control measurement system that reflects the process flow listed in Figure 1 can stabilize the process before the pressure relief system activates and prevents or reduces the amount of emission through relief systems, such as the flare stack and scrubber, diminishing the damage to the environment [6].…”

Section: Target Processmentioning

confidence: 99%

“…In this regard, this study performs the hazard and operability assessment (HAZOP) of the methanol separation process, a highly hazardous process in the bisphenol A (BPA) plant, to evaluate the risk factors [4]. It is then followed by a quantitative analysis and accident damage prediction fault tree analysis (FTA) is used for processes Increased reliability of the measurement control systems can lead to a reduction and prevention of major industrial accidents caused by the malfunction of the control systems and improve the safety of the chemical processes in plants [5]. An ideal control measurement system that reflects the process flow listed in Figure 1 can stabilize the process before the pressure relief system activates and prevents or reduces the amount of emission through relief systems, such as the flare stack and scrubber, diminishing the damage to the environment [6].…”

Section: Introductionmentioning

confidence: 99%

Optimal Design of Safety Instrumented Systems for Pressure Control of Methanol Separation Columns in the Bisphenol a Manufacturing Process

Lee

Woo

2016

Sustainability

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A bisphenol A production plant possesses considerable potential risks in the top of the methanol separation column, as pressurized acetone, methanol, and water are processed at an elevated temperature, especially in the event of an abnormal pressure increase due to a sudden power outage. This study assesses the potential risks in the methanol separation column through hazard and operability assessments and evaluates the damages in the case of fire and explosion accident scenarios. The study chooses three leakage scenarios: a 5-mm puncture on the methanol separation column, a 50-mm diameter fracture of a discharge pipe and a catastrophic rupture, and, simulated using Phast (Ver. 6.531), the concentration distribution of scattered methanol, thermal radiation distribution of fires, and overpressure distribution of vapor cloud explosions. Implementation of a safety-instrumented system equipped with two-out-of-three voting as a safety measure can detect overpressure at the top of the column and shut down the main control valve and the emergency shutoff valve simultaneously. By applying a safety integrity level of three, the maximal release volume of the safety relief valve can be reduced and, therefore, the design capacity of the flare stack can also be reduced. Such integration will lead to improved safety at a reduced cost.

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“…Zhang et al [15] demonstrated that the simplified equations given in the standard are over simplistic and are more suitable for practicing engineers. The reliability block diagrams represent a success oriented logic system structure and hence the analyst will focus on functions rather than failures, and may thereby fail to identify all the possible failure modes [16]. The fault tree analysis is straightforward to handle for the practitioners and generates approximations which sometimes provide non-conservative results as argued by Dutuit et al [14].…”

Section: Introductionmentioning

confidence: 99%

Unavailability assessment of redundant safety instrumented systems subject to process demand

Alizadeh

Sriramula

2018

Reliability Engineering & System Safety

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The process industry has always been faced with the challenging task of determining the overall unavailability of safeguarding systems such as the Safety Instrumented Systems (SISs). This paper proposes an unavailability model for a redundant SIS using Markov chains. The proposed model incorporates process demands in conjunction with dangerous detected and undetected failures for the first time and evaluates their impacts on the unavailability quantification of SIS. The unavailability of the safety instrumented system is quantified by considering the Probability of Failure on Demand (PFD) for low demand systems. The safety performance of the system is also assessed using Hazardous Event Frequency (HEF) to measure the frequency of system entering a hazardous state that will lead to an accident. The accuracy of the proposed Markov model is verified for a case study of a chemical reactor protection system. It is demonstrated that the proposed approach provides a sufficiently robust result for all demand rates, demand durations, dangerous detected and undetected failure rates and associated repair rates for safety instrumented systems utilised in low demand mode of operation. The effectiveness of the proposed model offers a robust opportunity to conduct unavailability assessment of redundant SISs subject to process demands.

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Reliability analysis of safety-instrumented systems operated in high-demand mode

Cited by 26 publications

References 10 publications

Prognostic and health management for safety barriers in infrastructures: Opportunities and challenges

Prognostic and health management for safety barriers in infrastructures: Opportunities and challenges

Optimal Design of Safety Instrumented Systems for Pressure Control of Methanol Separation Columns in the Bisphenol a Manufacturing Process

Unavailability assessment of redundant safety instrumented systems subject to process demand

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