Showing papers in "Journal of Loss Prevention in The Process Industries in 2002"

Review of 62 risk analysis methodologies of industrial plants

Abstract: For about 10 years, many methodologies have been developed to undertake a risk analysis on an industrial plant. In this paper, 62 methodologies have been identified, these are separated into three different phases (identification, evaluation and hierarchisation). In order to understand their running, it seems necessary to examine the input data, methods used, obtained output data and to rank them in several classes. First, all the input data are grouped together into seven classes (plan or diagram, process and reaction, products, probability and frequency, policy, environment, text, and historical knowledge). Then, the methods are ranked in six classes based on the combination of four usual criteria (qualitative, quantitative, deterministic and probabilistic). And finally, the output data are classified into four classes (management, list, probabilistic and Merarchisation). This classification permits the appraisal of risk analysis methodologies. With the intention of understanding the running of these methodologies, the connections between the three defined previously criteria (determinist, probabilistic and determinist and probabilistic) are brought to the fore. Then the paper deals with the application fields and the main limitations of these methodologies. So the hierarchisation phase is discussed and the type of scale used. This paper highlights the difficulties in taking into account all risks for an industrial plant and suggests that there is not only one general method to deal with the problems of industrial risks.

A review of uses, environmental hazards and recovery/recycle technologies of perfluorocarbons (PFCs) emissions from the semiconductor manufacturing processes

Abstract: Perfluorocarbons (PFCs) are being used as etching/cleaning gases in microelectronic or semiconductor manufacturing processes. These compounds under industrial uses mainly include CF 4 (tetrafluorocarbon), C 2 F 6 (hexafluoroethane), C 3 F 8 (octafluoropropane), and cyclo-C 4 F 8 or c-C 4 F 8 (octafluorocyclobutane). From the globally environmental issues and regulatory points of view, it is urgent to control the emissions of these significant greenhouse gases from the industrial processes. This article reviews these PFCs in terms of physiochemical properties, industrial uses, and environmental hazards (e.g. global warming, and toxicity and exposure hazards). Further, it addresses some available recovery/recycle technologies (i.e. cryogenic condensation/distillation, pressure swing adsorption, and membrane separation) of process exhaust gases containing PFCs from semiconductor manufacturing processes in this review paper.

A mathematical model for predicting the flash point of binary solutions

Abstract: A mathematical model which may be used for predicting the flash point of binary solutions has been proposed and subsequently verified by experimentally-derived data, such data pertaining to an almost-ideal solution as also to highly non-ideal solutions. The results reveal that the model is able to precisely predict the flash point over the entire composition range of binary solutions for both ideal solutions and non-ideal solutions by way of utilizing the flash point of the individual components. The highly non-ideal solution like octane+ethanol exhibits the minimum flash-point behavior, which leads to the minimum on the flash point vs composition curve.

Inherent safety in offshore oil and gas activities: a review of the present status and future directions

Abstract: Inherent safety is a proactive approach for hazard/risk management during process plant design and operation. It has been proven that, considering the lifetime costs of a process and its operation, an inherently safer approach is a cost-optimal option. Inherent safety can be incorporated at any stage of design and operation; however, its application at the earliest possible stages of process design (such as process selection and conceptual design) yields the best results. Although it is an attractive and cost-effective approach to hazard/risk management, inherent safety has not been used as widely as other techniques such as HAZOP and quantitative risk assessment. There are many reasons responsible for this; key among them are a lack of awareness and the non-availability of a systematic methodology and tools. The inherent safety approach is the best option for hazard/risk management in offshore oil and gas activities. In the past, it has been applied to several aspects of offshore process design and operation. However, its use is still limited. This article attempts to present a complete picture of inherent safety application in offshore oil and gas activities. It discuses the use of available technology for implementation of inherent safety principles in various offshore activities, both current and planned for the future.

Selection of appropriate adsorption technique for recovery of VOCs: an analysis

Abstract: Realization of the adverse effects of volatile organic compounds (VOCs) in the environment and the consequent enforcement of stringent regulations, accelerated the research and developmental activities across the world for achieving economic solutions. As a result, several advanced concepts of adsorption, a commercialized separation technology, have emerged. The availability of so many options means the industrialists, consultants and researchers experience problems in selecting the appropriate one. The present paper, through analysis of the type and concentration of VOCs, VOCs vs adsorbent suitability, the extent of separation required, and different adsorption techniques based on traditional and new advanced concepts, is an attempt to establish a qualitative guideline for the selection of the appropriate technique for recovery of VOCs.

Analysis of hazard areas associated with high-pressure natural-gas pipelines

Abstract: The rupture of a high-pressure natural-gas pipeline can lead to outcomes that can pose a significant threat to people and property in the immediate vicinity of the failure location. The dominant hazards are thermal radiation from sustained fire and collapse of buildings from explosion inside or in a partially confined area enclosed by buildings. A simplified equation has been developed that relates the diameter, the operating pressure and the length of pipeline to the size of the affected area in the event of a full-bore rupture. The equation is based on release rate, gas jet and heat flux from fire to estimate the hazard area. Hazard area is directly proportional to the operating pressure raised to a half power, and to the pipeline diameter raised to five-fourths power, but inversely proportional to the pipeline length raised to a quarter power. The simplified equation will be a useful tool for safety management of high-pressur natural-gas pipelines.

A criterion for developing credible accident scenarios for risk assessment

Abstract: Maximum credible accident analysis is one of the most widely used concepts in risk assessment of chemical process industries. Central to this concept is the aspect of ‘credibility’ of envisaged accident scenarios. However, thus far the term credibility is mostly treated qualitatively, based on the subjective judgement of the concerned analysts. This causes wide variation in the results of the studies conducted on the same industrial unit by different analysts. This paper presents an attempt to develop a criterion using which credible accident scenarios may be identified from among a large number of possibilities . The credible scenarios thus identified may then be processed for detailed consequence analysis. This would help in reducing the cost of the analysis and prevent undue emphasis on less credible scenarios at the expense of more credible ones.

The Bhopal gas tragedy: could it have happened in a developed country?

Abstract: The Bhopal gas tragedy occurred in December 1984 wherein approximately 41 tonnes of deadly MIC was released in the dead of night. It caused the death of over 3000 people and continued life-long misery for over 300,000 with certain genetic defects passed on to the next generation. It happened in a plant operated by a multinational, Union Carbide Corporation, in a developing country, India. The tragedy has changed the chemical process industry (CPI) forever. The results have been new legislation with better enforcement, enhancement in process safety, development of inherently safer plants, harsher court judgements, pro-active media and NGOs, rights-conscious public, and a CPI management willing to invest in safety related equipment and training. These have already resulted in savings of several hundred lives and over a billion dollars in accident damages [Kletz, T. (1998a). Process plants: a handbook of inherently safer designs. London: Taylor & Francis. Sutton, I. Chemical Engineering, 106(5), (1999). 114]. However, thousands did not have to die for the world to realise the disaster potential of CPI. The question that still remains is whether such an accident could have happened in a developed country. The answer is ‘yes’, as a number of major accidents in the developed countries since 1984, such as the Piper Alpha oil platform fire (1988, 167 killed), the Zeebrugge ferry disaster (1987, 167 killed), Phillips petroleum fire and explosion (1989, 23 killed), the Challenger disaster (1986, 7 killed), Esso Australia Longford explosion (1998, 2 killed) have demonstrated. One or more of the following are the primary reasons for such disasters: The indifferent attitude of the management towards safety, the lax enforcement of the existing regulations by the regulatory bodies as well as unusual delays in the judicial systems. Such conditions can happen regardless of the level of development in a country. Hence, the Bhopal gas tragedy could have happened in a developed country too, albeit with a lower probability. This paper is concerned with the possibility and not with the probability value. It also points out that further significant advances in process safety will occur with fundamental research into the causes of accidents and with a move towards inherently safer design.

Assessing safety management systems

Abstract: Traditionally, both academe and practitioners have tended to address fire safety by focusing on technical aspects and looking for the immediate causes of fire incidents or accidents after they have taken place. More recently, organisations have focused on assessing the consequences of the fire risk inherent in their operations pro-actively. However, fire safety still tends to be addressed in isolation, though fire loss is an emergent property. An organisation's emergent property results from the interrelated activities of people who design it, manage it and operate it. There is still a need for a systemic approach to understand the systemic nature of fire safety. This paper describes a fire safety management system (FSMS) model that aims to maintain fire risk within an acceptable range in an organisation's operations in a coherent way. This systemic approach can be used as a diagnostic tool to assess the effectiveness of existing safety management systems (SMS). It is hoped that this approach will lead not only to more effective management of fire safety, but also to more effective management of safety, health and the environment for any organisation.

Acrylic reactor runaway and explosion accident analysis

Abstract: On May 18, 2001 a destructive fire and explosion accident occurred in an acrylic resin manufacturing plant located in the northern part of Taiwan. More than 100 people were injured and totally 46 plants including 16 high-tech companies nearby were severely damaged. The resulting blast wave destroyed and shattered many large and small windows of residences within half-a-kilometer. The immediate cause turned out to be a vapor cloud explosion and the blast mass was estimated to be equivalent to 1000 kg of TNT. However, the original cause was found to be a runaway reaction of a 6-ton reactor that contained methyl acrylate, methyl alcohol, acrylonitrile, isopropyl alcohol, acrylic acid, methacrylic acid, and benzoyl peroxide. The investigation and experimental runaway results revealed that during the runaway, the temperature had risen rapidly from 60°C to about 170–210°C and the maximum temperature rising rate could reach 192 K min −1 . Since the final temperature of the process was much higher than the boiling points of all the reactants, vapors generated inside the reactor were released to the atmosphere. Certain hazards analysis and calorimetric tests to ensure that similar runaway accident should not occur again were performed as part of this study.

Quantification of inherent safety aspects of the Dow indices

Abstract: The Dow fire and explosion index (F&EI) and chemical exposure index (CEI) have been successfully implemented in a Visual Basic environment as a tool for the inherent safety assessment of chemical processes. Subprograms were developed to quantify the inherent safety aspects of the Dow indices. These aspects are presented graphically with the indices on the vertical axis and an inherent safety indicator on the horizontal axis. Dow indices of the MIC storage unit involved in the Bhopal disaster were evaluated to quantify the effects of process temperature, pressure and inventory of hazardous materials on the index values. As operating pressure was reduced, the F&EI decreased in accordance with the principles of inherent safety. The change in F&EI due to reduction of inventory was more significant than that resulting from pressure reduction. The results show that the F&EI change, given the same range of the independent variables (quantity of hazardous materials, operating temperature and pressure), is larger when a unit in the process area is evaluated compared to a unit in a storage area (tank farm). Reduction of the inventory of hazardous materials had no direct effect on the CEI for vapor releases, whereas the size of the hole diameter impacted the CEI to a great extent. However, there is a significant change in the CEI as the inventory of materials decreases for liquid releases involving temperatures above their flash and boiling points. Pressure reduction decreases the CEI, whereas temperature reduction leads to an increase in the CEI when these parameters are treated independently.

Evaluation of gas release rate through holes in pipelines

Abstract: A mathematical model of an accidental gas release in a long transmission pipeline is presented in terms of computational fluid mechanics. It was found that the hole model is suitable for the release of gas through a small hole, while the pipe model is suitable for the gas release through a hole corresponding to the complete breaking of the pipe. In this paper, a new model was proposed for a hole that lies between both these situations. The results of the example show that when the initial inside pressure is higher than 1.5 MPA, the mass of gas released during the sonic flow is more than 90% of the total mass of gas released. The average release rate of the total release process could be substituted by the average release rate of the sonic flow, or by 30% of the initial release rate. This approximation would become more accurate with the increase in the initial inside pressure.

A review of environmental hazards and adsorption recovery of cleaning solvent hydrochlorofluorocarbons (HCFCs)

Abstract: Hydrochlorofluorocarbons (HCFCs) are being used as interim replacements for chlorofluorocarbons (CFCs) that cause significant stratospheric ozone depletion and global warming relating to the greenhouse effect. HCFCs under commercial uses such as cleaning solvents include HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane), HCFC-141b (1,1-dichloro-1-fluoroethane), HCFC-225ca (3,3-dichloro-1,1,1,2,2-pentafluoropropane), and HCFC-225cb (1,3-dichloro-1,1,2,2,3-pentafluoropropane). From the environmental, ecological, and regulatory points of view, it is important to limit and control the emissions of these cleaning solvents from the surface finishing processes. Adsorption technology has been utilized for many years to recover organic vapors by using carbon-based or zeolite-based adsorbent. This article aims to introduce these HCFCs in terms of physiochemical properties, commercial uses, and environmental hazards (i.e., stratospheric ozone depletion, global warming, and health & safety). Further, the main studies on the adsorption isotherm and desorption methods of these HCFCs by various adsorbents (i.e., granular activated carbon, activated carbon fiber, and hydrophobic zeolite) are reviewed in this paper.

Minimum ignition energy (MIE) — a basic ignition sensitivity parameter in design of intrinsically safe electrical apparatus for explosive dust clouds

Abstract: In general terms, the purpose of any safety standard is to define borderlines between safe and unsafe conditions, with reasonable safety margins. The electrical spark ignition sensitivity of dust clouds (MIE) varies over at least eight orders of magnitude. Therefore, in the case of intrinsically safe electrical apparatus to be used in the presence of explosive dust clouds, substantial differentiation of the minimum requirements to prevent ignition by electrical sparks is needed. The present paper proposes a method by which adequate differentiation of required maximum permissible currents and/or voltages in intrinsically safe electrical circuits to be used in explosive dust clouds can be achieved. In essence, the concept is to use conservative first-order ignition curves, calculated or estimated from the experimental MIE value of clouds in air of the actual dust. Charts to be used for design purposes are given in the paper. Internationally standardised test methods allow MIE for clouds of any dust to be determined, at least down to the range of a few mJ. There is, however, a need for a supplementary method covering the range of lower energies, down to 0.01 mJ.

HazMat transport through Messina town: from risk analysis suggestions for improving territorial safety

Abstract: In this paper, after briefly outlining the main features of TRAT2, its application to the land transport of dangerous goods through the downtown of Messina is outlined. Owing to its particular location, there is a large flow of hazardous materials through the city of Messina. Many of these substances come from the greatest industrialised areas of Sicily. Goods reach the town by rail or road, and cross the Straits by ship. A complete inventory of dangerous substances, detailed in the paper, was the basis of a complete risk analysis, whose results, obtained by means of the TRAT2 software, have been analysed and discussed. From both individual risk distribution and societal risk curves the importance of parameters has been obtained and this has suggested measures to improve the safety of the urban area.

Design and evaluation of safety measures using a newly proposed methodology “SCAP”

Abstract: An increase in the number of accidents in the process industries and the concomitant damage potential is a cause of concern in many countries. In order to control the alarming risk posed by these industries, the United States government has asked each manufacturing facility to carry out a worst-case disaster study and to develop alternatives to control this high risk. Other developed and developing countries such as Canada and India have taken similar measures. Recently Khan and Abbasi (J. Loss Prevent. Process Ind. (2001a) in press) have proposed a maximum credible accident analysis with a maximum credible accident scenario approach, which scores over a worst-case scenario approach for being realistic and reliable. In another effort, Khan and Abbasi (J. Hazard. Mater. (2001b) in press) have developed an efficient and effective algorithm for probabilistic fault tree analysis. These two approaches have been combined to yield a new methodology for a more realistic, reliable, and efficient safety evaluation and the design of risk control measures. The methodology is named SCAP: Safety, Credible Accident, Probabilistic fault tree analysis. The methodology is comprised of four steps of which the last step is a feedback loop. This paper recapitulates this methodology and demonstrates its application to ethylene oxide (EO) plants. The application of SCAP to EO plants identifies five units as risky and needing more safety measures. Further, this study recommends safety measures and demonstrates through SCAP that their implementation lower the risk to an acceptable level.

An inverse approach for piping networks monitoring

Abstract: Spills and leakages of hazardous fluids from piping networks may pose a significant safety risk to population, industrial plants and the environment. Therefore in fluid distribution the problem of monitoring the network status in order to identify abnormal conditions and locate leakages arises. In the paper an inverse approach resorting to a multi-layer perceptron back-propagation Artificial Neural Network (ANN) is proposed, in order to locate leakages based on pressure and flow rate information. Strategies for generating input data and for correlating by ANN such data to the fluid distribution system status are presented. A two-level architecture is selected, composed by a main ANN at the first level and several branch-specific second-level ANNs in cascade to the main one. The branch in which the leakage occurs is identified, resorting to the ANN operating at the first level, while the specific second-level ANN is activated to estimate accurately the magnitude and location of the leakage in the selected branch.

Solution adaptive CFD simulation of premixed flame propagation over various solid obstructions

Abstract: This paper presents the results of a number of calculations carried out in order to simulate combustion past obstacles of different shape and blockage ratio. The obstacle shapes considered are circles, squares, triangles and flat plates. Two-dimensional simulations are carried out with the McNEWT code. The code solves the reacting flow field with a laminar flamelet model on an unstructured mesh. Adaptive mesh refinement is applied so that the flame front is accompanied by mesh refinement throughout the calculation domain. A transition from laminar to turbulent combustion induced by passage past the obstacle is seen in the simulations. Evidence for the transition is found in the change in flame shape, flame speed and pressure. The simulations are compared with experimental data and there is good agreement between experiment and simulation.

A new algorithm for computer-aided fault tree synthesis

Abstract: Fault tree analysis (FTA) has been used in the chemical process industry (CPI) for systematic safety and reliability analysis during the past decades. Conventional manual construction of fault trees can be extremely time consuming and vulnerable to human error. A computer-aided fault tree synthesis methodology can be an initial step, or as an independent check to assist or supplement manual FTA. However, no entirely satisfactory algorithm has been published for fault tree synthesis, especially when control loops are encountered. A potential methodology to construct fault trees automatically is proposed in this paper. This algorithm works directly form the system block diagram, thus avoids the tedious work of generating digraphs, transition tables, decision tables, and knowledge-based rules. Mini cause-and-effect trees are used to model the cause and effect logics around each item of equipment. Control loops are treated by special cause-and-effect unit models — logical combinations of the unit models of their constituent components. Multiple or complex control loops can be easily taken into account by providing their corresponding cause-and-effect unit models. In particular, the fault tree construction algorithm presented here is based on a component-by-component basis instead of a loop-by-loop or node-by-node basis. The tree structure is much more concise and easier to read. An example is embedded in the description of the methodology for better understanding. Analysis shows that the fault tree generated here is equivalent to the published result.

Accident investigation of an ABS plant

Abstract: A severe dust explosion occurred in the silos area of an acrylonitrile–butadiene–styrene (ABS) plant. A total of six silos that contained fine powders exploded sequentially. The powders were polystyrene–acrylonitrile (SAN) and ABS powders containing low and high content of polybutadiene latex (PBL). All the top plates and bag-filters of the silos flew away in various directions. At first a thermal runaway or dust explosion were suggested as possible causes for the destruction of the silos assemblies. The thermal hazard from the oxidation of PBL segments in ABS powder was rejected following thermal analysis using the DSC and VSPII calorimeters (from the time history), residual analysis, fragments of explosion and burning behavior on the dust layer after explosion. Finally a dust explosion was concluded where the bulked brush discharging was the possible ignition source for the successive dust explosions. The TNT equivalent and the consequences of the explosion were calculated and compared with the recorded situations in the silos area.

Study of the severity of industrial accidents with hazardous substances by historical analysis

Abstract: This paper studies the levels of risk in industrial facilities where hazardous substances are used, evaluating the influence of certain variables on the severity of the accidents that have occurred until now. It makes use of the incidents recorded in the July 2001 version of the MHIDAS database. This study reveals that accidents in developed countries are less severe than those that occur in other geographical areas. Also, it establishes the influence on the severity (number of fatalities) of this kind of incident of certain factors: the type of incident and the type and amount of substance involved. Lastly, the extent to which current facilities comply to the risk tolerance criteria in various countries is evaluated with regards to incidents involving explosions.

Flammability of kerosene in civil and military aviation

Abstract: The investigation of the ignition conditions of kerosene vapors in the air contained in an aircraft fuel tank contributes to the definition of onboard safety requirements. Civil and military kerosene are characterized by specification. The specification of civil aviation kerosene is based upon usage requirements and property limits. while military kerosene is primarily controlled by specific chemical composition. Characterization of the flammability properties is a first step for the establishment of aircraft safety conditions. Flash point, vapor pressure, gas chromatography analysis, and flammability properties of the kerosene used by the French Military aviation (F-34 and F-35 kerosene) are compared with the flammability properties of civil kerosene. The empirical law established by the Federal Aviation Administration (FAA) in 1998, expressing the ignition energy in terms of fuel, temperature, flash point and altitude is modified and expressed in terms of fuel temperature, flash point and pressure.

Assessing the self-heating behaviour of Callide coal using a 2-metre column

Abstract: A 2-m, adiabatic column has been successfully refurbished and recommissioned for coal self-heating research at The University of Queensland. Subbituminous coal from the Callide Coalfields reached thermal runaway in just under 19 days from a starting temperature of 20-22 degreesC. The coal was loaded as two layers, with an R-70 index of 2.73 degreesC h(-1) and 5.90 degreesC h(-1) for the upper layer and lower layer respectively. Initially, a hotspot developed in the upper layer between 120 and 140 cm from the air inlet due to moisture adsorption. After 7 days, self-heating in the lower half of the column began to take over, consistent with the higher R-70 index of this coal. The location of the final hotspot was approximately 60 cm from the air inlet. Further tests on Australian coals, with the column, will enable a better understanding of coal self-heating under conditions closely resembling mining, transport and storage of coal. The results from the column will also provide industry with the information needed to manage the coal self-heating hazard. (C) 2002 Elsevier Science Ltd. All rights reserved.

Investigation of the flammability zone of o-xylene under various pressures and oxygen concentrations at 150 °C

Abstract: Knowledge of material safety properties is essential for safe handling during unit operations, as incidents in plants can often be traced to an insufficient knowledge of the hazardous properties of combustible or flammable substances. If determined carefully and applied properly, safety-related properties will provide information on the reaction behaviors and possible fire and explosion hazards of the specific substance. The aim of this study was to investigate the safety-related properties of o -xylene (e.g., flammability limits, minimum oxygen concentration, maximum explosion overpressure, and flammability zone). These properties were determined with a 20-L-Apparatus at a mixing operation temperature of 150 °C and under initial pressures of 760, 1520 mmHg, and 2280 mmHg, respectively. An empirical equation was established from the experimental results for the effects of initial pressure on flammability limit. Potential hazards of unit processes in phthalic anhydride plants are also mentioned.

Risk and consequence analyses of hazardous chemicals in marshalling yards and warehouses at Ikonio/Piraeus harbour, Greece

Abstract: The risk and the consequences of possible accidents at Ikonio (Piraeus harbour, Greece) are investigated and analyzed in this paper. At this harbour large cargoes of dangerous chemicals (toxic or flammable) are unloaded and stored in warehouses or in marshalling yards. Houses and a school are located near the plant and are directly exposed to danger in the case of an accident. The results were obtained by Breeze Hazard Professional software package, which contains several models for performing consequence modeling through quantitative risk assessment.

Influence of trace impurities on chemical reaction hazards

Abstract: The influence of trace impurities is frequently mentioned as a possible or probable cause of accidents in the chemical industry. In process conditions where there is a potential for a fast exothermic decomposition or polymerisation reaction, the contamination of pure chemicals by trace impurities may cause problems. Typical examples of this situation are described concerning the processing of organic nitrocompounds and the storage of reactive monomers, i.e. vinyl acetate and ethylene oxide. In some process instances, i.e. hydrogenation of organic nitrocompounds, trace impurities in the organic substrate are said to have killed the catalyst and caused severe accidents. Many contaminants are known to be catalyst killers in hydrogenation processes. Examples of accidents or runaway reaction hazards caused by trace impurities are given, based on a review of the literature and on our own data. Trace impurities present in common raw materials make their processing more complex and may cause accidents. Two examples are considered, the presence of nitrogen trichloride in chlorine manufacture and the presence of hydrogen sulphide and mercaptans in petrochemical feed-stock. A full literature review is given.

Effective environmental management through life cycle assessment

Abstract: Unplanned and unsustainable development (particularly rapid industrialisation) has placed great pressure in every dimension of the environment (air, water, soil, health, etc.). The resulting disturbance in the natural ecological balance is a serious concern. Sustainable development is the need of the hour; it can only be achieved through effective environmental management. Environmental management will become indispensable in the future as regulatory restrictions tighten and public expectations of environmental performance increase. The day is not far away when a customer will prefer to buy products produced by an environmentally committed organisation. In short, the environmental commitment of an organisation will become a market strategy. Environmental management is a set of actions based on a structured methodology to ensure that an organisation is committed to the environment and that the production process has minimal/no adverse affect on it. This article emphasises environmental management in the real engineering sense of the term, and discusses how to develop an effective environmental management system through life cycle assessment. It further demonstrates through a real life case study how an industry has achieved landmark success in managing its environment, production, as well as winning the good faith of society.

On the use and misuse of detected onset temperature of calorimetric experiments for reactive chemicals

Abstract: The interpretation of the detected onset temperature for DSC and other calorimetric measurements used for Reactive Chemicals is briefly discussed in terms of calorimeter sensitivity and reaction dynamics. Common misinterpretations are also addressed. It is shown that the detected onset temperature should not be considered as an upper stability limit for a process defining the ‘start’ of undesired reactions. It is also not a point below which processes can operate safely at any temperature. In the latter case, an arbitrary choice of operating somewhere below a detected onset temperature can stall desired chemistry, lead to an over-conservative safety margin impacting cycle time/production rates, or provide a false sense of security triggering serious consequences. An understanding of the heat gain rates and heat loss rates is necessary to engineer for safe operations.

Technical modeling in integrated risk assessment of chemical installations

Abstract: This paper presents the technical model of an Integrated Quantitative Risk Assessment method, taking into account management as well as technical design and producing risk level measures. The basic steps of the technical model consist in developing a Master Logic Diagram (MLD) delineating the major immediate causes of Loss of Containment and associated quantitative models for assessing their frequency. Appropriate management models quantify the parameters of the technical model on the basis of the safety management system of the installation. The methodology is exemplified through its application on the risk assessment of a LPG scrubbing tower of an oil refinery. A detailed technical model simulating the response of the system to various initiating events is developed, along with a detailed model simulating the influence of the plant-specific management and organizational practices. The overall effect is quantified through the frequency of release of LPG as a result of a Loss of Containment in scrubbing towers of the refinery.