Bayesian Networks on Risk Analysis of a Regasification System on an Offshore Unit

2011 ◽  
Author(s):  
Adriana Miralles Schleder ◽  
Marcelo Ramos Martins ◽  
Gilberto Francisco Martha Souza
Keyword(s):  
Risk Analysis ◽  
Bayesian Networks ◽  
Failure Modes ◽  
Terrorist Attack ◽  
Fault Trees ◽  
Reliability Centered Maintenance ◽  
Considerable Impact ◽  
Cut Set ◽  
Maintenance Plan

Nowadays, LNG Import Terminals (where the storage and regasification process is conducted) are mostly onshore; the construction of these terminals is costly and many adaptations are necessary to abide by environmental and safety laws. Moreover, an accident in one of these plants might produce considerable impact in neighboring areas and population; this risk may be even worse due to the possibility of a terrorist attack. Under this perspective, a discussion is conducted about a vessel known as FSRU (Floating Storage and Regasification Unit), which is a storage and regasification offshore unit, that can work miles away from de coast and, owing to this, can be viewed as an option for LNG storage and regasification facilities. The goal is to develop a method for using Bayesian Networks in the Risk Analysis of Regasification System of the FSRU, which will convert Fault Trees (FT) into Bayesian Networks (BN) providing more accurate data. Using BN is possible to represent uncertain knowledge and local conditional dependencies. In addition, FT models the failure modes as independent and binary events while BN may model a larger number of states. It is worth noting that BN does not require the determination of cut sets; however, given a failure, it is capable of providing the probability of each possible cut set. This method will provide information to define, in a future study, a maintenance plan based on the Reliability Centered Maintenance. The results intend to clarify the applicability of BN on risk assessment and might improve the risk analysis of a Regasification System FSRU.

scholarly journals Condition-Based Maintenance of HVAC on a High-Speed Train for Fault Detection

Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1418
Author(s):  
Lorenzo Ciani ◽  
Giulia Guidi ◽  
Gabriele Patrizi ◽  
Diego Galar
Keyword(s):  
Decision Making ◽  
High Speed ◽  
Failure Modes ◽  
Air Conditioning System ◽  
Suggested Approach ◽  
Reliability Centered Maintenance ◽  
High Speed Trains ◽  
Optimal Maintenance ◽  
The Cost ◽  
Maintenance Plan

Reliability-centered maintenance (RCM) is a well-established method for preventive maintenance planning. This paper focuses on the optimization of a maintenance plan for an HVAC (heating, ventilation and air conditioning) system located on high-speed trains. The first steps of the RCM procedure help in identifying the most critical items of the system in terms of safety and availability by means of a failure modes and effects analysis. Then, RMC proposes the optimal maintenance tasks for each item making up the system. However, the decision-making diagram that leads to the maintenance choice is extremely generic, with a consequent high subjectivity in the task selection. This paper proposes a new fuzzy-based decision-making diagram to minimize the subjectivity of the task choice and preserve the cost-efficiency of the procedure. It uses a case from the railway industry to illustrate the suggested approach, but the procedure could be easily applied to different industrial and technological fields. The results of the proposed fuzzy approach highlight the importance of an accurate diagnostics (with an overall 86% of the task as diagnostic-based maintenance) and condition monitoring strategy (covering 54% of the tasks) to optimize the maintenance plan and to minimize the system availability. The findings show that the framework strongly mitigates the issues related to the classical RCM procedure, notably the high subjectivity of experts. It lays the groundwork for a general fuzzy-based reliability-centered maintenance method.

Application of Reliability Centered Maintenance in a Hydrocracker

2011 ◽  
Vol 317-319 ◽  
pp. 1837-1842
Author(s):  
Jian Feng Huang
Keyword(s):  
Risk Analysis ◽  
Failure Modes ◽  
Maintenance Strategies ◽  
Reliability Centered Maintenance ◽  
Rotating Machineries

The paper presents a case study: the review of the reliability centered maintenance (RCM) methodology realized in a hydrocracker. Applying of the reliability centered maintenance methodology, it finds 495 failure modes and ranks risk priorities for the 98 rotating machineries in the hydrocracker. According to the results of risk analysis, it provides customized maintenance strategies for each component of the hydrocracker, which would improve the safety of the hydrocracker effectively. The review provides helpful reference for other equipments in refinery factories.

scholarly journals A Matrix FMEA Analysis of Variable Delivery Vane Pumps

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1741
Author(s):  
Joanna Fabis-Domagala ◽  
Mariusz Domagala ◽  
Hassan Momeni
Keyword(s):  
Risk Analysis ◽  
Failure Modes ◽  
High Reliability ◽  
Matrix Analysis ◽  
Hydraulic Systems ◽  
Vane Pump ◽  
End Effects ◽  
Root Cause ◽  
Preventative Measures ◽  
Fmea Analysis

Hydraulic systems are widely used in the aeronautic, machinery, and energy industries. The functions that these systems perform require high reliability, which can be achieved by examining the causes of possible defects and failures and by taking appropriate preventative measures. One of the most popular methods used to achieve this goal is FMEA (Failure Modes and Effects Analysis), the foundations of which were developed and implemented in the early 1950s. It was systematized in the following years and practically implemented. It has also been standardized and implemented as one of the methods of the International Organization for Standardization (ISO) 9000 series standards on quality assurance and management. Apart from wide application, FMEA has a number of weaknesses, which undoubtedly include risk analysis based on the RPN (Risk Priority Number), which is evaluated as a product of severity, occurrence, and detection. In recent years, the risk analysis has been very often replaced by fuzzy logic. This study proposes the use of matrix analysis and statistical methods for performing simplified RCA (Root Cause Analysis) and for classification potential failures for a variable delivery vane pump. The presented methodology is an extension of matrix FMEA and allows for prioritizing potential failures and their causes in relation to functions performed by pump components, the end effects, and the defined symptoms of failure of the vane pump.

RISK ANALYSIS OF OFFSHORE TRANSPORTATION ACCIDENT IN ARCTIC WATERS

2021 ◽  
Vol 159 (A3) ◽  
Author(s):  
R Abbassi ◽  
F Khan ◽  
N Khakzad ◽  
B Veitch ◽  
S Ehlers
Keyword(s):  
Monte Carlo ◽  
Risk Analysis ◽  
Historical Data ◽  
Fault Trees ◽  
Northern Sea Route ◽  
Accident Scenarios ◽  
Oil Tanker ◽  
Harsh Conditions ◽  
Monte Carlo Framework ◽  
Transportation Accident

A methodology for risk analysis applicable to shipping in arctic waters is introduced. This methodology uses the Bowtie relationship to represent an accident causes and consequences. It is further used to quantify the probability of a ship accident and also the related accident consequences during navigation in arctic waters. Detailed fault trees for three possible ship accident scenarios in arctic transits are developed and represented as bowties. Factors related to cold and harsh conditions and their effects on grounding, foundering, and collision are considered as part of this study. To illustrate the application of the methodology, it is applied to a case of an oil-tanker navigating on the Northern Sea Route (NSR). The methodology is implemented in a Markov Chain Monte Carlo framework to assess the uncertainties arisen from historical data and expert judgments involved in the risk analysis.

Technical Analysis of Ocean Towing Evolutions

2021 ◽  
Author(s):  
Bartley Eckhardt ◽  
Daniel Fridline ◽  
Richard Burke
Keyword(s):  
Failure Modes ◽  
Human Life ◽  
Single Point ◽  
Forensic Analysis ◽  
Sea State ◽  
Worst Case ◽  
Strain Monitoring ◽  
Load Limit ◽  
Offshore Oil

Ocean towing in general, and non-routine tows in particular, present unique technical challenges to towing vessel owners/operators, salvors, the offshore oil/gas and wind industries, and others. When such tows “go wrong”, the harm to human life, property and/or the environment can be significant. The authors have drawn from their work on the Towing Safety Advisory Committee’s investigation of the grounding of the MODU Kulluk to present methods and considerations in analyzing ocean towing evolutions, both “routine” and “non-routine”. (TASK 14-01) The methods and considerations presented should be employed in advance of a towing evolution, but can be used in accident reconstruction and forensic analysis when an evolution has failed. The methods presented are iterative, and consider 2 x 6 degree freedom of motion (of the towing vessel(s) and towed vessel respectively) and characteristics of the towline, and facilitate determination of: Worst Case Conditions. Extreme Towline Tension (ETT) as a function of sea state and speed. Limits of the Tow (Go-No Go Criteria). Recommended Catenary Length as a function of sea state and speed. Size and Selection of the Towing Vessel and Gear, including: Required Bollard Pull. Required Strength, Characteristics and Condition of the Towline. Limits and Set Points of the Towing Winch, Automatic or Manual. Required Strength and Characteristics of the Synthetic Emergency Towline and its methods of deployment and connection. Working Load Limit (WLL) of the Shackles, Delta Plate and Attachment Points. Required Strength and Characteristics of Bridles, Pendant and Surge Gear/Shock Lines. The authors further explore the implications of single point failure modes, redundancy in gear and towing vessel(s), high cycle fatigue, and strain monitoring.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

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