Safety Engineering Tools Research Articles

Eliminating the Occurrence and Consequences of Toxic Release in Petrochemical Industry through Intervention of Safety Engineering Tools

The aim in this project is to analyze the risk associated with different toxic releases which is occurring in the chemical industry and to minimize its release using safety engineering tool in order to make the working environment safer. The sector of petrochemical industries is very important and have specific place in our country. Since the beginning, the Indian petrochemical industry has shown an enviable growth rate. This industry also contributes largely to the economy of the country and the growth and development of manufacturing industry as well. Petrochemical industry has a high risk of toxic release. The main causes of accidents are the chemical splashes which can occur for instance when a pipe or a tank burst under pressure or during disassembling operations of pipes or valves. There are a number of ways of toxic release at each and every process of petrochemical industry. We have identified the way in each process of the petrochemical industry. We have taken H2S as toxic gas and performed analysis, with the help of Bowtie methodology. Result obtained by evaluating various processes in petrochemical industry, we found that H2S can be released in three major sections i.e. transportation, storage and processing units. Using bowtie method, resolutions has been done to decrease or eliminate the possibilities of leakage of H2S

Minimum ignition energy of hydrogen-air mixtures at ambient and cryogenic temperatures

The ignition and combustion of hydrogen in air is considered more hazardous compared to other fuels due to the lower minimum ignition energy (MIE) and the wider flammability range. Spark discharge is the most common type of electrostatic ignition hazard. There is a need in validated safety engineering tools to accurately calculate MIE in a wide range of temperatures from atmospheric to cryogenic which are characteristic for hydrogen systems and infrastructure. Current MIE assessment methodologies rely on the availability of experimental data on quenching distance and/or laminar burning velocity and thus are mostly empirical correlations. This prevents their application beyond the limited number of experimental data, i.e. to arbitrary composition of the hydrogen-air mixture at arbitrary temperatures including cryogenic. This work aims at the development of a model able to accurately predict MIE for hydrogen-air mixtures with arbitrary initial composition and temperature. Cantera and Chemkin software are used to calculate the properties and unstretched laminar burning velocity of hydrogen-air mixtures. The flame thickness is found to well represent the critical flame kernel in the suggested model. The model is validated against experimental data on MIE for mixtures at ambient and cryogenic (down to 123 K) temperatures. Results show that the effect of flame stretch and preferential diffusion shall be considered to accurately predict MIE for lean hydrogen-air mixtures, which was not possible for previous models.

MEASURING THE VARIABILITY OF THE PEDESTRIAN CROSSING FUNCTION IN THE SOCIO-TECHNICAL SYSTEM OF URBAN ROAD TRANSPORT

In some areas of transportation systems, reduction of risk using typical safety engineering tools can be difficult due to the relatively small number of events that can be analysed to draw conclusions for the future. One way out of this situation is to analyse systems in their normal operation when no adverse event occurs. It can be done, inter alia, with the Functional Resonance Analysis Method. An important research problem in this context is how to describe the variability of system functions. In this article, we propose an original method, based on the number of hazard sources present in a given analysis domain and apply it to a real pedestrian crossing. The obtained results indicate that the quantitative coincidence measures proposed by us are a convenient way to capture ‘functional vibrations’ in real socio-technical systems. This allows the prediction of undesired states of such systems based on their normal operation.

Examining the role of road safety audits worldwide: exploring road safety expert’s opinions

Road safety audit (RSA) is a method used to proactively identify safety risks in road projects from planning, design, and construction stages. The effectiveness of the implementation of RSAs varies across the globe. This paper provides an understanding of road safety auditor’s opinions and attitudes by using data collected from an online questionnaire filled by 408 road safety experts with varying demographic and technical backgrounds. Results demonstrated that majority of respondents agreed that RSA is an effective tool to improve road safety. Compared to high-income countries, respondents from low- and middle-income countries had less knowledge about RSA and less access to RSA guidelines. The results also indicate that many road safety auditors have a misunderstanding of the independence requirement for conducting RSA. The results of this paper can be used to inform and develop improved guidance to improve RSA generally and promote RSA as an effective road safety engineering tool.

Analyzing ignition data for fire modeling purposes

SummaryFire models, or other fire safety engineering tools, may require that input data be supplied for characterizing the ignition of combustible solids. This may be done in ad hoc manner and result in poor realism for modeling the ignition process. Extensive research on the ignition of solid materials has been done in recent decades, notably in characterizing the ignition time as a function of incident heat flux. This paper summarizes the highlights of what has been learned during such research. It then offers the user algorithms that may prove useful in the development or advancement of fire models. The suggested methods can also be valuable to performing simple (i.e., spreadsheet‐based) analysis of ignition data in order to extract effective thermophysicochemical properties of tested materials. Procedures for both thermally thick and thermally thin solids are presented. The previously developed procedures for a constant heating flux are extended to a time‐varying heat flux, with the latter based on the Duhamel superposition principle.

CLOSING KNOWLEDGE GAPS AND TECHNOLOGICAL BOTTLENECKS IN HYDROGEN SAFETY: A SNAPSHOT OF RECENT ACTIVITIES AT ULSTER UNIVERSITY

The paper presents the progress in hydrogen safety research at HySAFER Centre of Ulster University. It includes results of two research studies performed in 2019. The first study is on the leak-no-burst (LNB) safety technology for explosion free in a fire composite tanks for high-pressure gaseous hydrogen storage. The second study is on the validation of Ulster's models and safety engineering tools against large-scale experiment on hydrogen jet flame from high-pressure hydrogen pipeline.

Modelling and numerical simulation of pedestrian flow evacuation from a multi-storey historical building in the event of fire applying safety engineering tools

Abstract Fire prevention in museums is a much more complex matter because the safeguarding of human life must be integrated both with the protection of the cultural heritage of buildings and the unrepeatability of the works of art exhibited. While most fires cannot be prevented, implementing complementary safety measures can help both to mitigate the negative impacts and limit costs. This is an issue that researchers have little investigated over time and thus very few studies are available in the literature. The paper shows the results of fire simulation and visitors’ evacuation processes from one-exit multi-storey historical building, which is used prevalently as a museum, equipped additionally with a non-invasive supplementary countermeasure based on an automatic people entry flow control system in the hall of the building. For achieving the purpose of our research, an extension of the analysis tools generally applied in the field of engineering was made. Computational fluid dynamics (CFD) modelling showed that for all fire scenarios investigated the gradual spread of combustion gases and smoke is influenced by fire size, building geometry, and chimney effect along the ceiling and the stairwell. The very high temperatures that could endanger the building structure and lining occurred only in the fire room. Evacuation simulations showed the effectiveness of the current fire safety plan and equipment to manage fire emergencies, and suggested including in security procedures staff alert and guidance for a quick evacuation of visitors. People entry flow micro-simulation proved that the implementation of a control system, which counted both the number of visitors and those leaving the museum in the same time and stopped temporarily the passages through the entrance, prevented the possibility of having an overcrowded museum for the safety of occupants in the event of fire.

Blast wave from a high-pressure gas tank rupture in a fire: Stand-alone and under-vehicle hydrogen tanks

This study addresses one of knowledge gaps in hydrogen safety science and engineering, i.e. a predictive model for calculation of deterministic separation distances defined by the parameters of a blast wave generated by a high-pressure gas storage tank rupture in a fire. An overview of existing methods to calculate stored in a tank internal (mechanical) energy and a blast wave decay is presented. Predictions by the existing technique and an original model developed in this study, which accounts for the real gas effects and combustion of the flammable gas released into the air (chemical energy), are compared against experimental data on high-pressure hydrogen tank rupture in the bonfire test. The main reason for a poor predictive capability of the existing models is the absence of combustion contribution to the blast wave strength. The developed methodology is able to reproduce experimental data on a blast wave decay after rupture of a stand-alone hydrogen tank and a tank under a vehicle. In this study, the chemical energy is dynamically added to the mechanical energy and is accounted for in the energy-scaled non-dimensional distance. The fraction of the total chemical energy of combustion released to feed the blast wave is 5% and 9%, however it is 1.4 and 30 times larger than the mechanical energy in the stand-alone tank test and the under-vehicle tank test respectively. The model is applied as a safety engineering tool to four typical hydrogen storage applications, including on-board vehicle storage tanks and a stand-alone refuelling station storage tank. Harm criteria to people and damage criteria for buildings from a blast wave are selected by the authors from literature to demonstrate the calculation of deterministic separation distances. Safety strategies should exclude effects of fire on stationary storage vessels, and require thermal protection of on-board storage to prevent dangerous consequences of high-pressure tank rupture in a fire.

I-SafE: An integrated Safety Engineering Tool

Abstract: Traditionally, safety engineering has been a matter of tables and textual documents and even of pen and paper. Even in the age of computerization, this did has not really changed significantly, as the state of the practice in safety engineering is nowadays dominated by Excel sheets and Word files. Nevertheless, a range of computer-aided safety analysis and modeling techniques have emerged and are being put to good use. The problem here is, however, that there is a lack of profound integration between different safety artifacts on the one hand and the general engineering artifacts on the other hand. In addition, between the different safety analysis techniques and the regular engineering techniques, there is usually a range of different tools in use that are not really compatible with each other. To overcome this problem, we conceptualized and implemented an integrated multi-analyses and multi-viewpoint safety engineering tool that enables tight integration between different models within and across different engineering disciplines. This paper gives an overview of the main features of this tool.

SCHEMA-SI: A hybrid fire safety engineering tool Part II: Case study

SCHEMA-SI is an engineering tool able to evaluate the performance of building fire safety system. It uses a dynamic hybrid model, which means that discrete events and continuous phenomena are interconnected at every instant. The model has been developed as a tool to assist fire protection engineers in performing fire safety engineering calculations. This tool may be also used to conduct risk assessments and to evaluate the efficiency of selected design strategies in case of fire in a specific building. Part I of this paper describes SCHEMA-SI tool basis. This paper focuses on a real case study. The case study aims at evaluating and comparing four fire safety strategies in a French hotel.

The use of Petri nets and a two-zone model for fire scene reconstruction

Fire scene investigation relies on in situ investigation (observations that take place where the fire occurred) and laboratory analysis. Nowadays the role and place of fire modelling in fire forensic investigation are debated within the forensic community. The main objective of this work is to propose a methodology to consider the stochastic aspect of fire development in a specific case by using fire modelling. Therefore, a stochastic fire safety engineering tool so-called SCHEMA-SI (Stochastic Computation and Hybrid Event Modelling Approach-Sécurité Incendie) developed at the CSTB (French Scientific and Technical Construction Centre) has been used to reconstruct a fire scene that occurred in 2007 in a senior care facility situated in the Paris suburb (France). In this case study, several fire scenarios were generated with SCHEMA-SI from probabilistic data in order to perform fire scene investigation. Each scenario is composed on one hand by a succession of dated events and on the other hand by physical quantities time-evolution at different locations in the building (heat release rate, temperature, interface height…). The objective of this work was to find the scenarios which allow getting an acceptable agreement between the calculated values and the observations from the real situation in the fire scene. Among the thousands of fire scenarios generated, 20% were compliant with the fire scene observations. The analysis of these compliant scenarios gave a better idea of what might have happened in the care facility. At the end, the contribution of numerical simulation in a fire scene analysis is discussed.

Estimating Safety Benefits of Road Improvements: Case Based Approach

Improvements to road safety have become a high priority for road authorities due to increasing public awareness and concern of the high social and economic costs of collisions. However, satisfying this priority in an environment of limited budgets and growing fiscal constraints is difficult. It is therefore important to ensure that the funding available for road safety improvements is efficiently utilized. In an attempt to maximize the overall road safety benefits, safety professionals usually invoke a process to evaluate the cost effectiveness of road safety projects. Road safety benefits are normally determined using collision reduction factors (CRFs) that are reported in the road safety literature. However, the results from many previous safety studies are unreliable due to the inability to apply the CRFs to all conditions and because many safety studies suffer from problems with the evaluation methodology and accommodating the random nature of collisions. To resolve these problems, safety analysis software known as the information system for estimating crash reductions (ISECR) has been developed. Information system for estimating crash reductions is an intelligent database that uses a case-based reasoning approach to compile the results from previous road safety research. Information system for estimating crash reductions evaluates the applicability of the results by accounting for site-specific characteristics and the study methodology by assigning a quality score. The system determines the expected CRFs and the range and reliability associated with a safety improvement at a specific location. The evolution of ISECR, a description of current and future enhancements, and the applications for this road safety-engineering tool are the subjects of this paper.