Fault Tree Research Articles

Improvement of the occupational risk management process in the work safety system of the enterprise.

The research purpose is to improve the management of occupational risks associated with hazards as well as the organization's capabilities to identify hazardous factors (HFs) using the "BOW-TIE" method in accordance with the provisions of the ISO 45001:2019 standard. To improve occupational risk management, the "BOW-TIE" method has been introduced into occupational health and safety management systems. This approach facilitates a comprehensive description and analysis of potential risk development from identifying hazardous factors to studying the consequences. It visually integrates fault and event trees to provide a holistic view of risk dynamics. The improvement of the occupational hazard risk management process considers both internal and external factors affecting the organization, thereby increasing the probability and severity of potential hazardous events. The revised approach categorizes risk levels as acceptable, unacceptable, or verifiable. In addition, occupational risk management requires an in-depth analysis of the organization's external and internal environment to identify hazards that affect the probability and severity of potential hazardous events. This research proposes an innovative approach to occupational risk management by determining the magnitude of occupational risk as the cumulative result of assessing risks associated with all external and internal factors influencing the probability of hazardous event occurring. The introduction of the "BOW-TIE" method, combined with a comprehensive analysis of the organizational environments, facilitates a more effective and nuanced approach to occupational risk management.

HAZARD ANALYSIS AND RISK ASSESSMENT FOR SPINNING YARN PRODUCTION PROCESS BY INTEGRATED FTA-FMEA APPROCH

The hazard analysis and management is vital in textile industry to avoid accidents and wasting resources caused by the failures in production systems. Risk analysis is also very significant to decrease possible hazards and to avoid possible damage in manpower & production systems. In this study, an approach based on Failure Mode and Effects Analysis (FMEA) and Fault Tree Analysis (FTA) is proposed to analyse the ring spinning yarn production process in a textile industry. First, the possible hazards in the production line, yarn production system, in an integrated company operating in the textile sector are analysed by FTA method. Then, FMEA is applied to ring spinning yarn production process in a textile industry to rank all possible risks corresponding to hazards in descending order with respect to both occupational health and safety. It is very important to remove all possible hazards in textile industry to decrease the number of risks related to occupational health and safety. Therefore, in total of 57 hazard root causes are determined in the yarn production department. Subsequently, the faults related to the hazard root causes are examined by FTA and then risk corresponding to these hazards are prioritized by FMEA. The results obtained from the proposed FTA-FMEA approach show that decision makers and engineers can easily decrease the number of hazards and risks with respect to both occupational health and safety in practice

Coupling analysis of crane accident risks based on Bayesian network and the N-K model

Crane usage is pervasive on construction sites, however, it is associated with a notably high accident rate. The analyzing of crane accident risks is essential for accident prevention, control, and ensuring the safety of lifting operations. Hence, significant emphasis should be placed on understanding the interaction among various risk factors. This paper proposes a quantitative coupling method for human, machine, management, and environmental risk factors in crane accidents, leveraging Bayesian networks (BN) and the N-K model. Firstly, text mining technology and fault tree analysis are employed to analyze the causes of crane accidents and categorize the associate risk factors. Secondly, the types of risk coupling resulting from human, machine, management, and environmental risk factors are defined. Thirdly, the BN model is developed based on the analysis of crane accident risksand its N-K model. Fourthly, the parameters of the risk coupling nodes in the developed BN are determined based on the calculation results of the N-K model. Finally, for the risk coupling types with high coupling values and the first-level node and second-level node, the failure probability is analyzed through posterior probability and sensitivity analysis. The results indicate that factors related to man and management significantly impact crane accidents and warrant enhanced attention. The interplay among multiple risk factors significantly influences the probability of crane accidents, necessitating careful attention.

Estimation of uncertainty in computation of importance factors and probability of undesirable events for safety-critical multi-unit systems, based on Binary Decisions Diagrams

This paper addresses current needs of the Multi-Unit Probabilistic Safety Assessment (MUPSA) methodology, which consists of a series of eight essential steps for conducting Probabilistic Safety Assessment (PSA) in the context of a multi-unit Nuclear Power Plant (NPP), co-located on a single site. The focus of this study revolves around one of the steps of the MUPSA methodology, which includes the examination of the importance factors and uncertainty analysis. Emphasizing the role of this step within MUPSA, the paper highlights the hypothesis and estimations made, along with the determination of system importance factors and failure frequency. To illustrate the practical application of these concepts, the paper presents three illustrative examples. The first example involves a 3-terminal reliability network, while the second example features an illustrative calculation applied to a system designed for potential use in a real NPP, compared to a Monte-Carlo simulation. Moreover, the second example involves the evaluation of a medium voltage distribution system (MVDS) designed to meet the auxiliary supply requirements of a nuclear power plant. This analysis is performed using a binary decision diagram (BDD), and the results derived from the BDD evaluation are then verified with those obtained through a Monte Carlo simulation for a comprehensive comparative analysis. Finally, an uncertainty analysis is achieved using a BDD reliability model, using the results of fault trees developed by National Company SN Nuclearelectrica S.A. (SNN), Department of Nuclear Safety, in the context of the Coordinated Research Project (CRP- I31031).

Operational reliability analysis of remote operated vehicle based on dynamic Bayesian network synthesis method

In this study, we propose a reliability framework that combines the GO method with fault tree analysis and integrates human factor reliability analysis. Taking the application of remotely operated vehicle (ROV) in underwater oil and gas production as an example, a reliability model of ROV operation process is established. The human reliability in the ROV operation process is analyzed on the basis of Cognitive Reliability and Error Analysis Method (CREAM) extension approach. The influence of human factor reliability and equipment reliability on the system is compared and analyzed. The importance of each operation step is also compared and analyzed. A sensitivity analysis of the ROV during operation is performed. This study provides a theoretical basis for the improvement and maintenance of the operational reliability of ROV. The proposed reliability modeling approach solves the reliability analysis problem of large and complex operating systems.

Risk identification of integral pressurized water reactor (IPWR) cooling system using a combination HAZOP, FMEA, and FTA methods

AbstractIntegral Pressurized Water Reactor (IPWR) is gaining attention for use in Indonesia due to lower initial capital investment, sitting flexibility, and high level of inherent safety. IPWR relies heavily on passive cooling systems that have many advantages but lacks operational experience because no one operates commercially. Therefore, it is necessary to carry out a risk analysis related to passive cooling system failures that may occur during operation. Even if conventional risk analysis methods are applied singularly, the results still have shortcomings. This study aims to integrate the use of the Hazard and Operability Analysis (HAZOP), Fault Tree Analysis (FTA), and Failure Mode and Effect Analysis (FMEA) methods to identify risks in the IPWR primary cooling system during normal operation. HAZOP was used to identify hazards, FTA analyzed the root causes of the critical problems, and the basic event's FMEA was developed for risk ranking and mitigation measures. This combined methodology makes risk assessment more systematic and comprehensive because it manages entity‐wide risk. The results offer valuable insights for stakeholders involved in decision‐making regarding the development of nuclear power plants (NPPs) in Indonesia.

Analyses and algorithms of personnel safety in mines using event tree and Bayesian network method

Determination of the hazard index in ensuring the safety of personnel in underground mines requires a comprehensive approach. Different methods can be applied depending on the specifics and conditions of work. This article discusses event tree and Bayesian network methods as tools for systematic analysis and assessment of personnel safety risks. The event tree method allows the sequence of events that lead to certain outcomes to be ordered and visualised. Analysing this event tree can help identify critical points and determine likely ways to prevent accidents. The Bayesian grid method is a graphical model of the probabilistic relationships between different variables. When analysing personnel safety, the Bayesian grid method can take into account the probability of events, the factors affecting safety and their interrelationships.

Analysis of the Work Environment and Occupational Health, Safety (K3) in the Carton Box Packaging Industry Using the Fault Tree Analysis (FTA) Method (Case Study of Pt. Carton Box Manufacturing Bekasi Regency)

The cardboard box packaging industry is a form of innovation in paper-based packaging products which includes outer protective packaging for food, automotive and other finished products, PT. Cikarang Cardboard Box Manufacturing is a multi-national company that operates in the field of manufacturing paper-based packaging sourced from paper recycling processing, so that in its operations it still pays attention to environmental aspects for the continuation of the next generation. As a provider of large-scale cardboard packaging, the company certainly has business ethics and occupational health and safety (K3) regulations that must be adhered to by all employees and guests who visit it, however there are still cases of work accidents that occur every year, the measurement of the level of work accident cases is based on data obtained based on direct observation, Therefore, work health and safety (K3) analysis research was carried out using the Fault Tree Analysis (FTA) method. From the analysis carried out by researchers, it was found that the cause of work accidents that occurred was due to employee understanding, bad habits that occurred (unsafe action). and the work environment is in an unsafe condition. So the solution to this problem is that it is hoped that the company can tighten K3 regulations in the company environment in order to improve company performance and reduce the number of work accidents that occur in the company environment.

Analysis of Product Defects in Stay Horn Parts duringthe Welding Process Using Fault Tree Analysis (FTA) and Failure Mode and Effects Analysis (FMEA)

The company in this study is an automotive company that produces, among other things, stay horn parts. The issue faced by the company is that the defect rate in stay horn parts exceeds the standard, with a defect rate of 2.06%, while the company's standard is set at 1%. This study aims to identify the highest cause of defects, determine the Risk Priority Number (RPN), and provide improvement suggestions to reduce the defect rate to meet the company's established standards. The methods used for this research are Fault Tree Analysis (FTA) and Failure Mode and Effect Analysis (FMEA).

АНАЛИЗ МЕТОДОВ ОЦЕНКИ РИСКОВ В ОБЛАСТИ ПРОИЗВОДСТВЕННОЙ БЕЗОПАСНОСТИ НА АВИАПРЕДПРИЯТИИ

The article discusses various methods of risk assessment in the field of of process safety at an airline. The purpose of the study is to determine the most appropriate risk assessment method to increase the level of safety at work and reduce the probability of dangerous situations. When analyzing the methods for detecting and identifying hazardous events and negative situations, we have highlighted the most effective ones. Based on this, the authors have created diagrams such as the "tree of incidents" and the "tree of events" has been developed for the event: industrial injury. The article considers the matrix method as one of the most common methods in the practice of professional risk assessment.

Zero-suppressed ternary decision diagram algorithm for solving noncoherent fault trees in probabilistic safety assessment of nuclear power plants

Probabilistic safety assessment (PSA) plays a critical role in ensuring the safe operation of nuclear power plants. In PSA, event trees are developed to identify accident sequences that could lead to core damage. These event trees are then transformed into a core-damage fault tree, wherein the accident sequences are represented by usual and complemented logic gates representing failed and successful operations of safety systems, respectively. The core damage frequency (CDF) is estimated by calculating the minimal cut sets (MCSs) of the core-damage fault tree.Delete-term approximation (DTA) is commonly employed to approximately solve MCSs representing accident sequence logics from noncoherent core-damage fault trees. However, DTA can lead to an overestimation of CDF, particularly when fault trees contain many nonrare events. To address this issue, the present study introduces a new zero-suppressed ternary decision diagram (ZTDD) algorithm that averts the CDF overestimation caused by DTA.This ZTDD algorithm can optionally calculate MCSs with DTA or prime implicants (PIs) without any approximation from the core-damage fault tree. By calculating PIs, accurate CDF can be calculated.The present study provides a comprehensive explanation of the ZTDD structure, formula of the ZTDD algorithm, ZTDD minimization, probability calculation from ZTDD, strength of the ZTDD algorithm, and ZTDD application results. Results reveal that the ZTDD algorithm is a powerful tool that can quickly and accurately calculate CDF and drastically improve the safety of nuclear power plants.

REDUCCIÓN DE RIESGO DE FALLOS EN IMPRESORA 3D MEDIANTE EL USO SECUENCIAL DE DFMEA, ARBOL DE FALLOS Y REDES BAYESIANAS

The need to manufacture reliable devices, which include features that guarantee good performance and do not cause problems for the end user, is of paramount importance for manufacturers. To meet this objective, it is necessary to perform a thorough analysis of the devices to identify potential failure events in order to be able to take actions to reduce their risk of occurrence and increase the reliability and quality of the device. This research paper presents an effective tool for the detection from the design of possible failures in the devices, which allows actions to be taken for their correction in early stages. This analysis methodology combines several advanced fault analysis techniques, such as DFMEA, Fault Tree, and Bayesian networks, making the process of analyzing, detecting and correcting potential device failures more efficient. This methodology is applied to the analysis of a commercial 3D printer that uses fused filament deposition technology model Anet A8, making a preliminary filter using a DFMEA for subsequent analysis fault tree and Bayesian network managing to determine the probability of occurrence of 3D printing failures, this allows to take actions and establish priorities of corrective actions focused on reducing the risk of failure based on its probability of occurrence. Keywords: DFMEA, Fault tree, Bayesian Network, 3D printing, Fault probability

ОГЛЯД МЕХАНІЗМІВ ROOT CAUSE АНАЛІЗУ ТЕЛЕКОМУНІКАЦІЙНИХ МЕРЕЖ

Telecommunication networks are an integral part of modern information society, providing data transmission and communication among millions of users worldwide. The complexity and scale of these networks are constantly growing, which increases the demands on their reliability and stability. One of the key tasks in ensuring the efficient operation of telecommunication networks is the identification and elimination of the root causes of failures and anomalies that can significantly affect the quality of service for end users. Root cause analysis (RCA) is a powerful tool for identifying the primary causes of problems, preventing their recurrence, and enhancing the overall reliability of networks. The article provides a detailed review of contemporary methods and tools of RCA used in telecommunication networks. In particular, methods such as fishbone diagram analysis, the «five whys» method, fault tree analysis, and the application of machine learning for big data analysis are considered. Each of these approaches has its advantages and disadvantages, and their comprehensive use allows for higher accuracy and efficiency in identifying the root causes of problems. Practical examples demonstrate the effectiveness of applying various RCA methods to solve specific problems in telecommunication networks. For instance, the use of fishbone diagram analysis and the «five whys» method allows for the identification of the primary causes of network delays and equipment issues at base stations. The implementation of failure prediction systems based on machine learning significantly enhances network reliability by allowing for the early detection of potential problems and the necessary technical measures. The prospects for the development of RCA in telecommunication networks are outlined. The primary focus is on the development of adaptive and self-learning systems capable of dynamically responding to changing network conditions. The use of more complex artificial intelligence algorithms and tools for predicting potential problems will significantly improve the effectiveness of RCA and ensure high-quality telecommunication services.

A Deductive Fault Analysis Method Based on Hypergraphs

Fault tree analysis is a system malfunction hazard evaluation quantitative and qualitative procedure. The method is well-known and widely used, especially in the safety systems domain, where it is a mandatory integral part of the so-called ”Hazard Evaluation” documentation. This paper proposes an alternative or complementary deductive fault analysis method: it uses system topology to build a hypergraph representation of the system to identify component criticality and support loss of functionality probability evaluation. Once automated, the proposed method seems promising when the system engineers explore the different architectures. They may have indication about architecture’s reliability without continuous feedback from the system safety team. The system safety team must check the solution once the engineers select the final architecture. They can also use the proposed method to validate the correctness of the fault tree analysis.

Risk assessment on low levels of nacl salt using fault tree analysis in small and medium-sized industries Madura salt

Madura is the largest salt producer in East Java Province, with a percentage of production of 75% of the total, so this has a vast potential to produce an abundance of salt. The production stages are pre-production processes, production processes, and post-production. This study aimed to analyze NaCl levels and impurities in salt. Solving the problem requires risk analysis in salt manufacturing from start to finish. This study used the Fault Tree Analysis method, which was expected to find out the root of the problem in salt making. Data was collected by observing and documenting the salting site and interviewing salt farmers. The lab test result indicated that the NaCL levels of salt and seawater were below the standard, with an average NaCL level of 85%, where NaCL levels were less than 94% and had a water content of more than 5%. The NaCl content of seawater was also below the standard, with an average content of 51%, whereas usually, seawater contains NaCL of 86%. In addition, the lab test result for Pb contains, as impurities, was 1.33 ppm. This result was categorized as low level where the standard of Pb cannot allowed above 10 ppm.

Design of Power Transformer Fault Detection of SCADA Alarm Using Fault Tree Analysis, Smooth Holtz–Winters, and L-BFGS for Smart Utility Control Centers

Design of Power Transformer Fault Detection of SCADA Alarm Using Fault Tree Analysis, Smooth Holtz–Winters, and L-BFGS for Smart Utility Control Centers

Process accident prediction using Bayesian network based on IT2Fs and Z-number: A case study of spherical tanks.

This study aimed to propose a novel method for dynamic risk assessment using a Bayesian network (BN) based on fuzzy data to decrease uncertainty compared to traditional methods by integrating Interval Type-2 Fuzzy Sets (IT2FS) and Z-numbers. A bow-tie diagram was constructed by employing the System Hazard Identification, Prediction, and Prevention (SHIPP) approach, the Top Event Fault Tree, and the Barriers Failure Fault Tree. The experts then provided their opinions and confidence levels on the prior probabilities of the basic events, which were then quantified utilizing the IT2FS and combined using the Z-number to reduce the uncertainty of the prior probability. The posterior probability of the critical basic events (CBEs) was obtained using the beta distribution based on recorded data on their requirements and failure rates over five years. This information was then fed into the BN. Updating the BN allowed calculating the posterior probability of barrier failure and consequences. Spherical tanks were used as a case study to demonstrate and confirm the significant benefits of the methodology. The results indicated that the overall posterior probability of Consequences after the failure probability of barriers displayed an upward trend over the 5-year period. This rise in IT2FS-Z calculation outcomes exhibited a shallower slope compared to the IT2FS mode, attributed to the impact of experts' confidence levels in the IT2FS-Z mode. These differences became more evident by considering the 10-4 variance compared to the 10-5. This study offers industry managers a more comprehensive and reliable understanding of achieving the most effective accident prevention performance.

МЕТОДИЧЕСКИЕ ПОДХОДЫ АНАЛИЗА БАНКОВСКИХ РИСКОВ ПО ОБЕСПЕЧЕНИЮ ГОСУДАРСТВЕННЫХ КОНТРАКТОВ

The article presents the main approaches used in the analysis of risks inherent in independent guarantees, which can be issued, among other things, by banks to secure government contracts. The circumstances that must be taken into account when examining risks are determined, with an emphasis on the order of their development. Recommendations are given for the application of the “fault tree” method. Significant vectors were also emphasized when analyzing guarantees of proper performance of contracts. A correlation was established in which risk factors lead to the inevitable occurrence of financial losses. The study concluded on the features of the contract system and the risks characteristic of it.

The etymology study of “fetish opposition” based on FTA analysis and the police PR avoidance approach

Abstract In the contemporary post-truth era, there is a marked increase in the individual’s need for emotional expression and self-awareness. This paper introduces and defines the concept of “Fetish Opposition” through etymological research. Employing fault tree analysis, this study analyzes the risk identification and structural importance of “Fetish Opposition” in the context of “Public Security Prohibition” enforced by police departments. This is approached from the perspective of security system engineering, aiming to elucidate the underlying issues and delineate strategies to mitigate the phenomenon of “anti-public security.” This exploration seeks to provide theoretical guidance for enhancing the effectiveness of public security organs. The findings indicate that “lack of law enforcement transparency” holds structural importance of 0.186 within the fault tree of “Fetish Opposition,” making it the most significant factor affecting the entire system. Based on this insight, the police public relations department could develop targeted strategies to prevent such situations, thereby also opening new avenues for research in social psychology and the stabilization of police-community relations.

Work accident risk analysis using HIRARC and FTA methods (Case study: Suwarno Meubel)

Suwarno Meubel is a business engaged in furniture production, which has risks related to occupational health and safety including workers carrying heavy wood manually, cutting wood with a table saw, painting wood with a spray gun, and so on. The purpose of this study is to find out the potential hazards that exist in each job and find the root causes of work accidents and then provide suggestions for improvements. The research method used is Hazard Identification Risk Assessment and Risk Control (HIRARC) to identify hazard risks and risk assessments for each job, after that, jobs with extreme values will be further analyzed using the Fault Tree Analysis method (FTA). The results of this study found 9 low categories of hazard risks, 12 moderate hazard categories, 4 high hazard categories, and 1 extreme hazard category. Risks in the extreme category were analyzed and found that there were 7 basic events, namely fatigue, lack of focus, lack of training, a limited number of PPE (goggles), no safety equipment on the machine, and no work procedures. The proposed controls are in the form of administrative control, PPE, and engineering.