Potential Failure Scenarios Research Articles

Frequency Analysis of Failure Scenarios from Shale Gas Development.

This study identified and prioritized potential failure scenarios for natural gas drilling operations through an elicitation of people who work in the industry. A list of twelve failure scenarios of concern was developed focusing on specific events that may occur during the shale gas extraction process involving an operational failure or a violation of regulations. Participants prioritized the twelve scenarios based on their potential impact on the health and welfare of the general public, potential impact on worker safety, how well safety guidelines protect against their occurrence, and how frequently they occur. Illegal dumping of flowback water, while rated as the least frequently occurring scenario, was considered the scenario least protected by safety controls and the one of most concern to the general public. In terms of worker safety, the highest concern came from improper or inadequate use of personal protective equipment (PPE). While safety guidelines appear to be highly protective regarding PPE usage, inadequate PPE is the most directly witnessed failure scenario. Spills of flowback water due to equipment failure are of concern both with regards to the welfare of the general public and worker safety as they occur more frequently than any other scenario examined in this study.

Failure analysis of the offshore process component considering causation dependence

Abstract Offshore oil and gas processing equipment operating in harsh environments poses high risk. This risk is further increased by the susceptibility of the equipment to natural disasters such as hurricanes and snowstorms due to harsh environments. When equipment functionality is compromised, it can become a hazard to personnel as well as to other equipment. The key safety practice on the offshore facility is to isolate the equipment and minimize consequences associated with processing equipment failures. When and how to isolate vulnerable equipment is a challenge due to limited understanding of the equipment’s susceptibility and dependency to failure causes and consequences. This paper presents a methodology to analyze potential failure scenarios considering causation dependency and also determine which parameter(s) have the most impact on the failure. The results of the analysis are used to identify most sensitive equipment and their potential failure causes. This analysis will help to develop effective risk management strategies focusing on critical equipment.

A novel risk assessment method for landfill slope failure: Case study application for Bhalswa Dumpsite, India.

Rapid population growth of major urban centres in many developing countries has created massive landfills with extraordinary heights and steep side-slopes, which are frequently surrounded by illegal low-income residential settlements developed too close to landfills. These extraordinary landfills are facing high risks of catastrophic failure with potentially large numbers of fatalities. This study presents a novel method for risk assessment of landfill slope failure, using probabilistic analysis of potential failure scenarios and associated fatalities. The conceptual framework of the method includes selecting appropriate statistical distributions for the municipal solid waste (MSW) material shear strength and rheological properties for potential failure scenario analysis. The MSW material properties for a given scenario is then used to analyse the probability of slope failure and the resulting run-out length to calculate the potential risk of fatalities. In comparison with existing methods, which are solely based on the probability of slope failure, this method provides a more accurate estimate of the risk of fatalities associated with a given landfill slope failure. The application of the new risk assessment method is demonstrated with a case study for a landfill located within a heavily populated area of New Delhi, India.

Risk-based safety analysis of well integrity operations

Assurance of well integrity is critical and important in all stages of operation of oil and gas reservoirs. In this study, well integrity is modeled during casing and cementing operations. Two different approaches are adapted to model potential failure scenarios. The first approach analyzes failure scenarios using bow-tie model which offers a better visual representation of the logical relationships among the contributing factors through Boolean gates. The second approach takes advantage of Bayesian network, both to model conditional dependencies and to perform probability updating. The analysis identified managed pressure drilling system, logging tool, slurry formulation, casing design, casing handling and running method, surge and swab pressures as critical elements of the well integrity model. A diagnostic analysis on the slurry formulation further identified pilot test(s) and the interpretation of the test(s) as key elements to ensuring integrity of cementing operation. Relevant safety functions and inherent safety principles to improve well integrity operations are also explored.

Failure Mode and Effect Analysis of Power Transformer Based on Cloud Model of Weight

As the key component of a power system, the power transformer directly impacts the reliability and safety of the system. Failure mode and effects analysis (FMEA) is a methodology used to analyze potential failure modes within a system and has been used extensively to examine the power transformer’s performance in various potential failure scenarios. However, the FMEA method has several flaws; for example, the non-differential analysis of evaluation index and the impossibility of evaluating the actual risk among risk priority number (RPN) values that on the surface are equal. The cloud model of weight incorporates the relative importance of index. This paper proposes applying FMEA based on the cloud model of weight to assess a power transformer for risk, and shows that this method can effectively overcome the defects of traditional FMEA assessment methods.

Probabilistic risk analysis in manufacturing situational operation: application of modelling techniques and causal structure to improve safety performance.

The use of probabilistic risk analysis in jet engines manufacturing process is essential to prevent failure. The objective of this study is to present a probabilistic risk analysis model to analyze the safety of this process. The standard risk assessment normally conducted is inadequate to address the risks. To remedy this problem, the model presented in this paper considers the effects of human, software and calibration reliability in the process. Bayesian Belief Network coupled to a Bow Tie diagram is used to identify potential engine failure scenarios. In this context and to meet this objective, an in depth literature research was conducted to identify the most appropriate modeling techniques and an interview were conducted with experts. As a result of this study, this paper presents a model that combines fault tree analysis, event tree analysis and a Bayesian Belief Networks into a single model that can be used by decision makers to identify critical risk factors in order to allocate resources to improve the safety of the system. The model is delivered in the form of a computer assisted decision tool supported by subject expert estimates.

VESSEL MAIN PROPULSION ENGINE PERFORMANCE EVALUATION

In general, the performance of a ship in service is different from that obtained on shipyard sea trial. Apart from any differences due to loading conditions, and for which due correction should be made, these differences arise principally from the weather, fouling and surface deterioration of the hull and propeller. The influence of the weather, both in terms of wind and sea conditions, is an extremely important factor in ship performance analysis. Consequently, the weather effects needs to be taken into account if a realistic evaluation is to be made. The primary role of the ship service analysis is a standard of performance data, under varying operational and environmental conditions. The resulting information, derived from this data, becomes the basis for operational and chartering decision. In addition, the part for the data records is to enable the analysis of trends of either the hull or machinery, from which the identification of potential failure scenarios and maintenance decisions can be derived. The traditional method of data collection is the deck and engine room log records, and this is the most commonly used method today. In terms of data processing and capabilities, this method of data collection is far from ultimate, since involves significant data distortion risk. Instrumentation errors are always a potential source of concern in performance analysis methods. Such errors are generally in the form of instrument drift or gross distortion of the reading. However, these can generally be detected by the use of trend analysis techniques. The procedure for the evaluation of the ship’s service performance, that relies on proven methods of main propulsion engine service data analysis used

Injury Prevention through Visualizing the Harc in Oil and Gas Industry, Schlumberger Asia Services Ltd

A hazard is a potential condition which either exists or not. It may have an independent existence or exist in combination with other hazards, sometimes called events, and the conditions can lead to an actual functional failure or accident. The way this exactly happens in one particular sequence is called a scenario. Often a system has many potential failure scenarios. A hazard analysis is used as the first step in a process used to assess risk. The result of a hazard analysis is the identification of different type of hazards. It also is assigned a classification, based on the worst case severity of the end condition. Through this project, all the activities happening in the MAHAPE Base of Schlumberger were visualized, thereby making the employees aware of the hazards associated with each activity and proper control measure that can be used in-order to cope up with those hazards.Hazard Analysis and Risk Control listings were made for the whole base which covered around 28 activities such as Electrical works, all Drilling &Measurement activities, etc. and also a draft Resource Management Plan was made. Out of 28 activities, the most severe ones were working at height, hot works like welding and mobile mechanical lifting. If the control measures proposed in the company are not implemented, the risk level is going to be catastrophic. So proper control measures are to be implemented. (The hazards identified in the base were very risky and proper control measures were implemented to reduce the risk to acceptable level.)

Operational Risk Analysis of LNG Loading

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 20982, ’Operational Risk Analysis of LNG Loading,’ by B.H.K. Chin, P. Friis-Hansen, and T.G. Saetren, Det Norske Veritas, originally prepared for the 2010 Offshore Technology Conference, Houston, 3-6 May. The paper has not been peer reviewed. The increased interest in risk analysis is the result of several operators wanting to understand properly their risks in the operational phase, and in this way, through proper preparedness, to avoid or mitigate incidents and major accidents and to improve resilience toward these unwanted events. The full-length paper presents the results of a detailed risk analysis of a liquefied natural-gas (LNG) export loading operation at a jetty. The analysis takes into account the interaction between the vessel crew and the land-based operators. Introduction The objective of operational risk management is to satisfy multiple requirements of multiple stakeholders to control losses from operations. One particular objective of an operational-risk-management system is that it should provide a strong ability to forecast conditions and give input to management before the development of dangerous conditions. A second objective is to approach risk in a holistic way in assessing risk from unwanted losses resulting from loss of life and property and the effects on the environment. This requires a thorough understanding of the technical-systems reliability, of the organizational performance, and of how the interaction between the two affects the total-systems performance. This implies that a practical requirement for risk management of unwanted losses during the operation phase is that the risk modeling should encompass the systemic interactions between technical and human organizations. The solution for systemic risk requires a holistic perspective in hazard identification, risk analysis, and risk mitigation. This may provide the operator with a useful set of risk-based indicators to guide the risk-management process. Case-Study Description The intent of the test case is to model the loading mode at an LNG jetty, identifying potential failure scenarios and determining the risk profile for the loading operation. The main objective is to determine the safety and on-time performance of the loading operation. The investigation examines the possibility of technical failures, the errors caused by individual human performance, the organizational influences on the operation, and the combined factors from interfacing two sets of technical and human organizational systems (i.e., the land-based jetty operation and the ship-based operation). The process of transporting LNG has inherent risks associated with it. The LNG is handled in cryogenic conditions and if released, the vaporized gas can form a flammable or explosive mix with air at a flammable range of 5 to 15% concentration. The LNG carrier is on fixed charter, and the delivery performance is affected directly by the on-time performance of the LNG loading.

Failure and damage tolerance aspects of railway components

Railway structures such as rails and axles are safety relevant components since any failure includes the risk of catastrophic derailment. This paper gives a brief overview on the most important potential failure scenarios driven by fatigue crack initiation and propagation and discusses the effects of important influencing factors such as vehicle weight and speed, track quality and environmental conditions. The present paper summarizes earlier work of the authors in this field.

Introduction to the damage tolerance behaviour of railway rails – a review

Despite substantial advantages in material development and in periodic non-destructive inspection together with periodic grinding and other measures in order to guarantee safe service, fatigue crack propagation and fracture is still in great demand as emphasised by the present special issue. Rails, as the heart of the railway system, are subjected to very high service loads and harsh environmental conditions. Since any potential rail breakage includes the risk of catastrophic derailment of vehicles, it is of paramount interest to avoid such a scenario. The aim of the present paper is to introduce the most important questions regarding crack propagation and fracture of rails. These include the loading conditions: contact forces from the wheel and thermal stresses due to restrained elongation of continuously welded rails together with residual stresses from manufacturing and welding in the field, which is discussed in Section 2. Section 3 provides an overview of crack-type rail defects and potential failure scenarios. Finally the stages of crack propagation from initiation up to final breakage are discussed.

Zonal Isolation Modeling and Measurements—Past Myths and Today's Realities

Summary Over the past 10 years, several papers have been published discussing the long-term mechanical durability of the cement sheath. The customary procedure is to use a model to predict potential failure scenarios and to subsequently design a sealant material that will not fail under the expected conditions. The predictive models are either analytical or finite-element models. The analytical models can only be applied to relatively simple situations that require a simplified set of input data. In these cases, the results are consistent with those of finite-element models. More complex situations can be simulated with finite-element models, but the input data requirements are far greater. Typically in the modeling papers, little information is included on how the input data is obtained. Because of this, several papers have been published that have proposed ways to obtain the input data, in particular the mechanical parameters of the set cement. Because typically these papers have addressed only one or two parameters however, the proposed methods are inconsistent. This paper critically reviews the published information and highlights the strengths and weaknesses of the previous approaches. Subsequently, the paper presents new measurement methods and data analysis techniques to determine cement mechanical parameters in sufficient detail to allow them to be implemented in any laboratory with appropriate equipment. The predictions using data from the new measurement methods have been verified at the field level through evaluation of actual wells. Finally, the methods have been used to demonstrate the mechanical durability of flexible cement systems aged at high temperatures for one year; this is the first time that such data have been presented on these systems.

Forecasting hazard scenarios and implications for the evaluation of countermeasure efficiency for large debris avalanches

The key objective of a slope failure study is to reduce deaths, injuries and property damage. Predictions of slope failures are mandatory to reduce hazard and vulnerability of elements at risk with appropriate warning policy and properly designed countermeasures. Numerical modelling has been recently used as an approach to back-analyse real events but few attempts have been carried out to forecast potential failure scenarios. Recently, a debris avalanche involving about 1.2 million m 3 of debris and a nearby debris slide flow with failure volume of 0.1 million m 3 occurred in the Italian Prealps from the accumulation of a paleo-landslide. Field surveys and monitoring revealed that the upper part of the slope above the largest recent landslide is unstable with a possible failure volume between 1 and 1.5 million m 3. We conducted comprehensive fieldwork and analyses including geological and geomorphological surveys, compilation of a landslide inventory map, collection of rainfall records, study of triggering mechanisms and geotechnical properties of the failed materials, slope stability analyses and back-analyses of the runout phase of the landslide events. Through a series of slope stability analyses, the possible failure volume, sliding surface and topography are estimated, consistent with field monitoring data. Furthermore, with the help of calibration through back-analyses of the past landslide events, we assign a given degree of danger to slope elements with analogous conditions. We then numerically predict the runout patterns and mobility of the potential instabilities. The effectiveness of the planned passive countermeasures for potential zoning management is evaluated.

Risk-Based Expenditure Allocation for Infrastructure Improvement

Traditional methods of modeling and simulating lifecycle for infrastructure management, including bridge management systems, commonly do not account for risk associated with potential failure scenarios. These methods need to be reexamined to take advantage of risk technologies. In this paper, methods for performing reliability computations and managing information that are suitable for risk-informed expenditure allocation in lifecycle management are proposed. The methods include structural reliability assessment methods and the analytic hierarchy method for multicriteria ranking. The paper also presents the advantages of using web-based computing through an example of system reliability assessment software that can be used in an interactive web environment.

97/03110 Combined (integrated) COREX ironmaking and DRI production technologies

Despite substantial advantages in material development and in periodic non-destructive inspection together with periodic grinding and other measures in order to guarantee safe service, fatigue crack propagation and fracture is still in great demand as emphasised by the present special issue. Rails, as the heart of the railway system, are subjected to very high service loads and harsh environmental conditions. Since any potential rail breakage includes the risk of catastrophic derailment of vehicles, it is of paramount interest to avoid such a scenario. The aim of the present paper is to introduce the most important questions regarding crack propagation and fracture of rails. These include the loading conditions: contact forces from the wheel and thermal stresses due to restrained elongation of continuously welded rails together with residual stresses from manufacturing and welding in the field, which is discussed in Section 2. Section 3 provides an overview of crack-type rail defects and potential failure scenarios. Finally the stages of crack propagation from initiation up to final breakage are discussed.

Seal testing of large diameter rocket motors

This investigative program examines leakage testing of elastomeric O-ring seals for a solid rocket casing and provides direction towards an improved nondestructive postassembly test. It also details test equipment for the Space Shuttle systems solid rocket boosters (SRB). The results are useful to designers of hardware for pressure containment vessels which use O-ring seals. Using several subscale seal and groove configuration test fixtures equipped with either two or three O-ring seals in series, seal integrity is investigated with both a pressure decay and flowmeter methods. Both types of test equipment adequately detect the practical range of expected seal leak rates of 1 to 0.0001 sccs. The flowmeter leak test equipment appears to reduce testing time substantially. Limited seal leakage testing is performed on full-sized rocket motor segment seals, a pre-Challenger short stack, providing comparison of bore seals to test specimen bore and face seals. The conclusions are that seal reliability, verified via a performance pressure test, can be affected by temperature, quantity of grease, test pressure, and seal pressure load direction. Potential seal failure scenarios including contamination, seal damage, and sealing surface damage are discussed. Recommendations are made for an improved test procedure.