Modeling Uncertainties in Mining Pillar Stability Analysis

7 - Process technology safety and hazard analysis

Industrial processes contain inherent risks and to assess such risks the use of Process Hazard Analysis (PHA) are commonly applied. The benefits of first principles qualitative and quantitative models and empirical knowledge support for PHA are explored. The use of qualitative hazard analysis based on functional modelling to guide hazard analysis is emphasized. The study proposes a framework for investigating potential hazard scenarios based on functional modeling, e.g. Multilevel Flow Modeling of process system. Subsequently quantitative hazard analysis is used to prioritize the hazard scenarios with highest potential. MFM represents the process on several levels of abstraction and supports logical inference. The potential hazard scenarios are ranked by likelihood and severity. Judgment about likelihood, severity and the tolerability of the resulting risk is made on a subjective basis using the empirical knowledge of the PHA team members. The potential hazard scenario generation procedure can be computer-aided. The proposed framework is applied for a water injection system to increase oil recovery from existing reservoir with better safety performance. Qualitative functional models are efficient for detailed description of possible accident scenarios. Domino effects can be visualized in an MFM model. The possible major accident scenarios are selected by likelihood and severity of their effects. The major accident scenarios can be examined in detail through further quantitative analysis. The hazard analysis of a water injection system demonstrates the feasibility and applicability of the proposed framework. In industrial practice, formulation of the major accident scenario is usually based on historical incidents and the outcome of HAZOP/HAZID type hazard identification studies. Such studies are dependent on the team and their collective knowledge rather than being systematic and objective in nature. The proposed framework performs systematic and comprehensive plant failure and consequence path generation by a computer-aided tool.

A safety-critical system comprising several interacting and software-intensive systems must be carefully analyzed to detect whether new functional requirements are needed to ensure safety. This involves an analysis of the systemic properties of the system, which addresses the effect of the interaction between systems and system parts. The paper compares two hazard analysis methods, which are often considered well-suited for such software-intensive systems: the Functional Hazard Analysis (FHA) and Systems-Theoretic Process Analysis (STPA). The focus is on the selection and improvement of the best methods, based on the lesson learned from the comparison of FHA and STPA. The analyses cover the hazard analysis processes, systemic properties, and the criteria of requirements. The paper concludes that STPA is the better choice over FHA. Insights are obtained to align both STPA and FHA methods with the broader topic on risk management, that is, hazard analysis method improvement, cautionary thinking, uncertainty management, and resilience management.

Enbridge’s decision to formalize a Process Hazard Analysis (PHA) program has taken the organization through a journey from an informal/ad hoc practice to a rigorous, standardized, best-practice-based process with selected methodologies and tools being applied to all capital and operation projects in the company. This paper begins with a description of past hazard practices in the oil and gas pipeline industry in relation to the application of a hazard analysis. The oil and gas pipeline industry is governed by PHMSA, NEB, TSB, and provincial OHSA regulations, but is not regulated by OSHA or EPA RMP. Using this regulatory framework as a reference, a standard corporate PHA at Enbridge was developed and implemented. The paper describes the process, the methodologies, and the associated templates and tools. The implementation strategy is also discussed, including training deployment and communication plans. Finally, a road map for continuous improvement describes how to make the process sustainable by closing the current process gaps in relation to best practices and achieving a maturity stage of execution.

In 1993, American Petroleum Institute (API) committees completed the task of writing and issuing two new significant standards: RP 75, "Recommended Practices for Development of a Safety and Environmental ManagementProgram for Outer Continental Shelf (OCS) Operations and Facilities'; and RP 14J, "Recommended Practice for Design and Hazards Analysis for Offshora Production Facilities. " RP 75 identifies the components of a Safety and Environmental Management Program (SEMP) and addresses the identification and management of safety and environmental hazards in design, construction,, startup, operation, inspection, and maintenance of new, existing, ormodified OCS oil and gas drilling and production facilities. RP 14J provides guidance information on process and mechanical design analysis and presents methodologies for hazards analysis of offshore production facilities. The two RPs provide excellent tools for use by owners, operators, and contractors who manage, design, and operate OCS facilities. The Minerals Management Service (MMS) has issued a Letter to Lessees and a Federal Register notice which encourage voluntary implementation of RP 75 by all OCS operators. The MMS will monitor the oil and gas industty's voluntaty implementation and compliance with RP 75 to determine if future regulatory activity is required. References and tables at end of paper. INTRODUCTION During 1993, the American Petroleum Institute published two new Recommended Practices (RP) that establish guidelines and practices designed to enhance the operation of offshore facilities in the Outer Continental Shelf (OCS). The RPs were the result of proactive efforts by two industrycommittees who worked in partnership with the Minerals Management Service (MMS) and the U.S. Coast Guard (USCG) in their development. The two RPs are:RP 75: "Recommended Practices for Development of a Safety and Environmental Management Program for OCS Operations and Facilities"RP 14J: "Recommended Practice for Design and Hazards Analysis of Offshore Production Facilities" The development of RP 75 had as its origin the Safety and Environmental Program (SEMP) concept which was originally proposed by the MMS in July 1991. This concept is intended to address recommendations identified by a study performed by a Marine Board committee of the National Research Council in 1990. The Marine Board's key findings and recommendations included: The current inspection program satisfies the literal requirements of the Outer Continental Shelf LandsAct (OCSLA) for annual and unannounced inspections of each OCS facility. In this sense, it fulfills MMS'S statutory mission. On the other hand, the OCSLA carries a broad mandate to promote safety of life and property and to protect the environment. The Marine Board believes that bythis measure the MMS effort is not totally successful, particularly in the light of greater public expectations regarding safety and environmental protection that have emerged since the OCSLA was amended in 1978. In any event, changes inthe OCS operating environment (including aging platforms, more complex systems and operations, activities in deeper water at greater distances from shore, and changing characteristics of operating companies) have created a need to upgrade the MMS inspection program in order to sustain in the future the generally good.

Accident root cause investigations often identify unplanned power outages as the cause of a catastrophic accident. Unplanned power outages can be an initiating event that leads to an emergency shutdown of a process unit. If the emergency shutdown is managed incorrectly, it can result in an uncontrolled release of hazardous chemicals.To prevent a catastrophic accident, it is necessary to employ one or more safeguards to interrupt the chain of accident events. A process hazards analysis is the most effective tool for identifying these safeguards and evaluating their effectiveness prior to an incident. Examples of such safeguards are emergency shutdown procedures with operator training, emergency shutdown systems (including safety instrumented systems), and backup power supplies.This article explores the ways in which hazard analysis and emergency planning can be utilized to ensure a safe transition to a secondary power source during an interruption of primary power. A case study of an accidental release of hydrochloric acid vapor is presented in which a safeguard failed to function during a power outage. An interesting feature of this incident was the excessive testing of the emergency power system that led to its premature and undetected failure. Thus, when commanded to operate during a power outage, the backup system failed. We illustrate how a layer of protection analysis, coupled with the development of best practices from industrial safety standards, would have suggested a better inspection and test protocol for the emergency power system. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011

Dynamic simulation for process hazard analysis: Affordances and limitations in the application to complex process systems

ABSTRACT: Room-and-pillar mining is a widely used method for rock salt extraction in underground mines, where pillar stability plays a critical role in ensuring mine safety and optimizing mineral recovery. This study investigates in-situ stress conditions in three underground rock salt mines in Pakistan using the flat jack method. Field measurements included pillar stresses, in-situ elastic modulus, and key geometric variables such as pillar dimensions, opening width-to-height ratio, extraction ratio, and overburden height. Additionally, salt block samples were collected for laboratory testing to determine geomechanical properties, including uniaxial compressive strength, Young's modulus, Brazilian tensile strength, and density. The results indicate that pillar stresses are proportional to overburden stress, with values ranging from 6.05 MPa to 11.97 MPa, confirming overall pillar stability. Regression analysis was performed to develop predictive models for in-situ stress and elastic modulus. Furthermore, a guideline chart was developed to assist in determining appropriate pillar dimensions for various spans and safety levels, providing a practical tool for mine design and stability assessment.

Petri-net models for comprehensive hazard analysis of MOCVD processes

Domino effects produce hazard scenarios that involve escalating consequences as a chain of linked events propagates throughout and beyond the process where they originate. Such scenarios have been the subject of accident survey studies and quantitative risk analyses but their identification in process hazard analysis (PHA) has received less attention. This article discusses the nature and types of domino effects and a procedure is provided to address them in PHA. The role of separate domino effects studies is described, insights into domino effects that can assist PHA practitioners are provided, and some pitfalls in addressing domino effects are identified. The identification of domino effects in PHA is illustrated using an actual accident that occurred in a refinery. © 2014 American Institute of Chemical Engineers Process Saf Prog 34: 220–227, 2015

Chapter 3 - Objective and Description of PHA, What-If, and HAZOP Reviews

Security for medical devices has gained some traction in the recent years following some well-publicized attacks on individual devices, such as pacemakers and insulin pumps. This has resulted in solutions being proposed for securing these devices, usually in stand-alone mode. Medical devices are however becoming increasingly interconnected and interoperable as a way to improve patient safety, decrease false alarms, and reduce clinician cognitive workload. Given the nature of interoperable medical devices (IMDs), attacks on IMDs can have devastating consequences. This work outlines our effort in understanding the threats faced by IMDs, an important first step in eventually designing secure interoperability architectures. A useful way of performing threat analysis of any system is to use attack trees. Attack trees are conceptual, multi-leveled diagrams showing how an asset, or target, might be attacked. They provide a formal, methodical way of describing the threats to a system. Developing attack trees for any system is however non-trivial and often requires considerable expertise in identifying the various attack vectors. IMDs are typically deployed in hospitals by clinical engineers who may not possess such expertise. We therefore develop a methodology that will enable the automated generation of attack trees for IMDs based on a description of the IMD operational workflow and list of safety hazards that need to be avoided during its operation. Both these pieces of information can be provided by the users of IMDs in a care facility. The contributions of this paper are: (1) a methodology for automated generation of attack trees for IMDs using process modeling and hazard analysis, and (2) a demonstration of the viability of the methodology for a specific IMD setup called Patient Controlled Analgesia (PCA-IMD), which is used for delivering pain medication to patients in hospitals.

In-Room MRI for Adaptive Radiotherapy for Cervical Cancer Using an Integrated MR-Guided Radiation Therapy System

Safety as the key quality property among RAMS (reliability, availability, maintainability, and safety) demonstrates the most stringent performance in correspondence with the safety requirements and performance standards like EN 50126. Meanwhile, GNSS (Global Navigation Satellite Systems) are penetrating the railway now widely in non-safety related applications as passenger information, fleet management, etc. GNSS also have great potential for safety-related applications in railway such as the train location determination function, which the safety performance needs to be assured through hazard analysis and risk assessment process. The train location determination by satellite-based localization system is elevating the train control to the next level. The European Train Control System (ETCS) has being trying to implementing Level 3, the Chinese Train Control System (CTCS) has been implementing CTCS Level 3 low cost especially for secondary lines, and the U.S. is implementing train control systems under Positive Train Control (PTC) requirements. The train control system needs GNSS to provide more accurate location information of trains, more flexible and condensed trains on tracks with the consistency of still keeping the current safety level or even improve safety. Some researchers are trying to understand the performance of GNSS (GPS / EGNOS / Beidou) for railway applications from the fundamental accuracy level. A satellite-based train localization unit (SaLuT) as the entity to perform the train location determination function is to bring the GNSS accuracy evaluation up to safety integrity according to the safety requirements and standards for risk assessment. One of the key consequential result derived from the train location is the adequate safety margin. The safety margin, which can also be called as “safe braking distance”, is a margin indicated to rail traffic that would allow the train to stop with the application of normal service braking. The safety margin estimation quality and the risk of the safety margin shows the hazard rate for the safety margin estimation function performed by the designed localization unit SaLuT. This paper discusses the safety margin estimation method considering both GNSS accuracy and integrity assessment aspects of SaLuT, in accordance of the settled safety requirements of location determination function. To analyze the hazard of the safety margin estimation, a formal method is applied to model the SaLuT behavior and functions. The formal method based on stochastic Petri net enables the modeling process to include the GNSS receiver collected real data on the test track into it. The safety margin estimation method together with the risk assessment method using the real data can generate quantitative indicators to represent the localization function and safety margin estimation quality. The data used for the analysis is collected in the Qinghai-Tibet railway line from Golmud station to Ganlong station by SaLuT installed on a locomotive along the track. With the stochastic Petri net model and the systematic equation using the real collected data to estimate the safety margin based on the GNSS technologies, the SaLuT can be validated and verified for its hazard rates, which provides information for the safety cases in order to meet the industrial normative requirements.

WESKEM, LLC’s Environmental, Safety and Health (ES&H) Department had previously assessed that a lack of consistency, poor communication and use of antiquated communication tools could result in varying operating practices, as well as a failure to capture and disseminate appropriate Integrated Safety Management (ISM) information. To address these issues, the ES&H Department established an Activity Hazard Review (AHR)/Activity Hazard Analysis (AHA) process for systematically identifying, assessing, and controlling hazards associated with project work activities during work planning and execution. Depending on the scope of a project, information from field walkdowns and table-top meetings are collected on an AHR form. The AHA then documents the potential failure and consequence scenarios for a particular hazard. Also, the AHA recommends whether the type of mitigation appears appropriate or whether additional controls should be implemented. Since the application is web based, the information is captured into a single system and organized according to the ≥200 work activities already recorded in the database. Using the streamlined AHA method improved cycle time from over four hours to an average of one hour, allowing more time to analyze unique hazards and develop appropriate controls. Also, the enhanced configuration control created a readily available AHA library to research and utilize along with standardizing hazard analysis and control selection across four separate work sites located in Kentucky and Tennessee. The AHR/AHA system provides an applied example of how the ISM concept evolved into a standardized field-deployed tool yieling considerable efficiency gains in project planning and resource utilization. Employee safety is preserved through detailed planning that now requires only a portion of the time previously necessary. The available resources can then be applied to implementing appropriate engineering, administrative and personal protective equipment controls in the field.