Showing papers in "Journal of Loss Prevention in The Process Industries in 2003"

Risk-based maintenance (RBM): a quantitative approach for maintenance/inspection scheduling and planning

Abstract: The overall objective of the maintenance process is to increase the profitability of the operation and optimize the total life cycle cost without compromising safety or environmental issues. Risk assessment integrates reliability with safety and environmental issues and therefore can be used as a decision tool for preventive maintenance planning. Maintenance planning based on risk analysis minimizes the probability of system failure and its consequences (related to safety, economic, and environment). It helps management in making correct decisions concerning investment in maintenance or related field. This will, in turn, result in better asset and capital utilization. This paper presents a new methodology for risk-based maintenance. The proposed methodology is comprehensive and quantitative. It comprises three main modules: risk estimation module, risk evaluation module, and maintenance planning module. Details of the three modules are given. A case study, which exemplifies the use of methodology to a heating, ventilation and air-conditioning (HVAC) system, is also discussed.

A taxonomy of performance influencing factors for human reliability analysis of emergency tasks

Abstract: This paper introduces the process for, and the result of, the selection of performance influencing factors (PIFs) for the use in human reliability analysis (HRA) of emergency tasks in nuclear power plants. The approach taken in this study largely consists of three steps. First, a full-set PIF system is constructed from the collection and review of existing PIF taxonomies. Secondly, PIF candidates are selected from the full-set PIF system, considering the major characteristics of emergency situations and the basic criteria of PIF for use in HRA. Finally, a set of PIFs is established by structuring representative PIFs and their detailed subitems from the candidates. As a result, a set of PIFs comprised of the 11 representative PIFs and 39 subitems was developed.

Seismic risk of atmospheric storage tanks in the framework of quantitative risk analysis

Abstract: The quantitative risk assessment of industrial facilities is based on integrated procedures to quantify human, environmental and economical losses related to relevant accidents. Accordingly, seismic risk analysis has to be integrated in order to obtain reliable results. In this work, some considerations regarding the intensity and probability of occurrence of earthquakes and the vulnerability of atmospheric storage tanks subjected to seismic actions are given. Structural vulnerability based on observational data has been processed in the form of “probit analysis”, a simple and useful statistic tool. Suggestions concerning industrial seismic-related accidental scenarios are also given.

On the determination of the laminar burning velocity from closed vessel gas explosions

Abstract: A methodology to determine the laminar burning velocity from closed vessel gas explosions is explored. Unlike other methods which have been used to measure burning velocities from closed vessel explosions, this approach belongs to the category which does not involve observation of a rapidly moving flame front. Only the pressure–time curve is required as experimental input. To verify the methodology, initially quiescent methane–air mixtures were ignited in a 20-l explosion sphere and the equivalence ratio was varied from 0.67 to 1.36. The behavior of the pressure in the vessel was measured as a function of time and two integral balance models, namely, the thin-flame and the three-zone model, were fitted to determine the laminar burning velocity. Data on the laminar burning velocity as a function of equivalence ratio, pressure and temperature, measured by a variety of other methods have been collected from the literature to enable a comparison. Empirical correlations for the effect of pressure and temperature on the laminar burning velocity have been reviewed and two were selected to be used in conjunction with the thin-flame model. For the three-zone model, a set of coupled correlations has been derived to describe the effect of pressure and temperature on the laminar burning velocity and the laminar flame thickness. Our laminar burning velocities are seen to fall within the band of data from the period 1953–2003. A comparison with recent data from the period 1994–2003 shows that our results are 5–10% higher than the laminar burning velocities which are currently believed to be the correct ones for methane–air mixtures. Based on this observation it is concluded that the methodology described in this work should only be used under circumstances where more accurate methods can not be applied.  2003 Elsevier Ltd. All rights reserved.

Abatement of ammonia and amines from waste gases: a summary

Abstract: The technologies that allow the abatement of ammonia and amines from waste gases are briefly described. Advantages and drawbacks of thermal and catalytic oxidation processes, condensation, adsorption on solids, scrubbing and biofiltration are discussed.

I-Risk: development of an integrated technical and management risk methodology for chemical installations

Abstract: This paper presents an integrated quantitative risk assessment method for hazardous installations, taking into account management as well as technical design and producing risk level measures. The key components of the I-Risk methodology are the technical model, the management model and their interface. The technical model consists of developing a master logic diagram (MLD) delineating the major immediate causes of loss of containment (LOC) and associated quantitative models for assessing their frequency. The management model consists of the tasks, which must be carried out systematically in the primary business functions (such as operations, emergency operations, maintenance and modifications). A management audit quantifies the quality of these management tasks. The management–technical interface modifies certain parameters of the technical model on the basis of the quality of the safety management system of the specific installation. The methodology is exemplified through its application to the risk assessment of an ammonia storage facility. A detailed technical model simulating the response of the system to various initiating events is developed along with a detailed management model simulating the influence of the plant-specific management and organisational practices. The overall effect is quantified through the frequency of release of ammonia as a result of a loss of containment in a storage tank and in a pipeline.

A general criterion to define runaway limits in chemical reactors

Abstract: A general runaway criterion valid for single as well as for multiple reaction types, i.e. consecutive, parallel, equilibrium, and mixed kinetics reactions, and for several types of reactors, i.e. batch reactor (BR), semibatch reactor (SBR) and continuous stirred tank reactor (CSTR) has been developed. Furthermore, different types of operating conditions, i.e. isoperibolic and isothermal (control system), have been analysed. The criterion says that we are in a runaway situation when the divergence of the system becomes positive (div>0) on a segment of the reaction path. The results show that this is a general runaway criterion than can be used to calculate the runaway limits for chemical reactors. The runaway limits have been compared with previous criteria. A considerable advantage, over existing criteria, is that it can be calculated on-line using only temperature measurements and, hence, it constitutes the core of an early warning runaway detection system we are developing.

Predicting the frequency of accidents in port areas by developing event trees from historical analysis

Abstract: The historical analysis of 828 accidents in port areas, which have been selected from a database, has been used to identify the sequences of the accidents. Processing these data has allowed the event trees and the probability of the various accident scenarios to be determined. By using these event trees and figures detailing the frequency of the events that initiated the accidents, as taken from various authors, the frequency of the accidents has been determined.

Technologies for the abatement of sulphide compounds from gaseous streams: a comparative overview

Abstract: The techniques that may be applied to the removal of sulphide compounds from gases are briefly described and discussed. Scrubbing and adsorption on solids allow the recovery of sulphur either as such (H2S or sulphide organics) or, after oxidation, as elemental sulphur or SO2. This is actually a good choice when the concentration is high enough for sulphur recovery. When sulphur concentration is very low, techniques such as thermal and catalytic combustion, oxidative scrubbing and biofiltration might be preferable to attain deodorization. However, combustion converts sulphur into SO2, while oxidative scrubbing gives rise to sulphate-containing solutions. Biofiltration mineralizes sulphur in a natural environmental friendly way, without producing secondary contaminants.

Predicting the self-accelerating decomposition temperature (SADT) of organic peroxides based on non-isothermal decomposition behavior

Abstract: By combining a recent proposed elaborately simulated decomposition kinetic method for organic peroxide with the Semenov model of thermal explosion, the self-accelerating decomposition temperatures (SADTs) of organic peroxides were predicted. The heat generation equation is based on a reaction rate equation, which was expressed by differentiation of a fractional conversion equation with respect to time. The kinetic parameters involved in the calculation are the contribution fraction φ i , the end point temperature T di , and the reaction temperature range parameter K Ti , which are directly determined by observing the thermal behavior of peroxides under non-isothermal decomposition condition. The non-isothermal decomposition behaviors of eight organic peroxides were measured by the heat flux calorimeter C80D. By using the experimental results and the developed method, the no return temperature and the self-accelerating decomposition temperatures of these substances in UN 25 kg test and 0.5 liter Dewar test were predicted. The predicted SADTs were in agreement with the literature values.

Binary liquid solutions exhibiting minimum flash-point behavior

Abstract: The sufficient conditions for a binary liquid solution to behave as a minimum flash-point solution and the equations to determine the minimum flash-point composition and minimum flash-point are proposed here. Since these sufficient conditions and the associated equations were derived based upon the derivative of flash point with respect to composition (solution composition effect upon flash point), such a derivative equation was derived, initially, based upon the flash point-prediction model proposed in a previous study and then verified by the application of experimental data. Subsequently, this derived composition effect upon the flash-point equation for a liquid solution was applied to derive both the sufficient conditions and equations referred to above, with such conditions and equations both being verified by comparison of predicted results with experimentally derived data. The results reveal that these derived conditions are satisfactory for the identification of the status of a liquid solution as being a minimum flash-point solution and the proposed equations satisfactory to successfully estimate the value of the minimum flash-point composition and the minimum flash point.

Self-ignition of dust at reduced volume fractions of ambient oxygen

Abstract: Experiments were performed to investigate the self-ignition behaviour of accumulations of four different technical dusts at oxygen volume fractions ranging from 1.3 to 21%. For this purpose a laboratory oven used for hot storage testing was modified to allow flushing with the pre-mixed oxygen/nitrogen mixture of the desired composition. It was found that for all sample volumes investigated the self-ignition temperatures were higher the lower was the oxygen volume fraction. In addition, the type of reaction changed obviously, since the apparent activation energy significantly decreased at oxygen volume fractions below 6%. However, it was still possible to observe exothermic effects at oxygen volume fractions as low as 1.3%. A numerical model was established to simulate the process of self-ignition including the coupled heat and mass transfer within the dust accumulation using a finite element solver. The model consists of six balance equations for the heat transfer and the transport of five chemical species. It shows that the model reflects self-ignition in dust accumulations with satisfying accuracy, as long as the input data generated by preceding experiments are reliable.

Critical condition of backdraft in compartment fires: a reduced-scale experimental study

Abstract: Backdraft is a special fire phenomenon in a limited-ventilation building It can develop from fires of either ordinary combustibles or ignitable liquids that become oxygen starved yet continue to generate a fuel-rich environment If abundant fresh air is abruptly supplied by opening a door or breaking a window, the hot gas in this vitiated building will rapidly combust and a fire ball and a blast wave will take place Backdraft has the characteristics of abrupt occurrence and powerful destruction, which may cause the death of people in situ and the collapse of the building In this paper, the results of a reduced-scale experimental test series are presented This reduced-scale compartment (length×width×height with 12 m × 06 m × 06 m) was fitted with one opening (width×height with 02 m × 06 m in the middle of the end wall) The experimental results show that the key parameter determining the occurrence of backdraft is the mass fraction of unburned fuel (ie unburned methane in this study) When the mass fraction of unburned fuel in compartment exceeds a critical value, ie 98% backdraft will take place

Evaluation on thermal hazard of methyl ethyl ketone peroxide by using adiabatic method

Abstract: Ketone peroxides are capable of spontaneous decomposition, and violent decomposition occurs if they contact with strong mineral acids. In this paper, an adiabatic method is used to investigate the thermal hazard of Methyl Ethyl Ketone Peroxide (MEKPO) and mixture of MEKPO with sulfuric acid in order to understand the effect of the contamination of sulfuric acid on the thermal stability of MEKPO. On the basis of experimental results, kinetic parameters of exothermic reaction of MEKPO and mixture of MEKPO with 1% sulfuric acid are estimated, and thermal hazard parameters, such as the initial exothermic temperature and the adiabatic temperature rise are obtained under real adiabatic condition. It can be seen from the results that the thermal hazard of MEKPO with sulfuric acid is more remarkable than that of MEKPO itself.

Ignitions of explosive dust clouds by smouldering and flaming agglomerates

Abstract: Surveys show that burning nests of dusts have been ignition source for dust clouds involved in industrial explosions. The literature indicates, however, that hot nests are a poor ignition source and are difficult to convey through powder handling plant. This paper describes some test in which clouds of dusts with a range of Minimum Ignition Temperatures (MITs) were dispersed around dust agglomerations smouldering and flaming at various temperatures. Smouldering nests of dusts prove to be poor ignition sources for most dust clouds, failing to ignite dusts even when there is a large difference between the nest temperature and the MIT of the dust cloud. Smouldering nests with temperatures above approximately 700–800 °C were, however, able to ignite sulphur clouds. Flaming nests, on the other hand, were able to ignite clouds of dusts up to the maximum MIT used, 600–675 °C.

Dynamic management of human error to reduce total risk

Abstract: Safety management in companies at the limit of risk criteria must be implemented in order to survive in the very aggressive and competitive environment of modern society. It implies that the risk in process industries is crossing the limit of safe practices. Most major accidents consist of human errors and mechanical component failures, and cannot be explained by a stochastic coincidence of independent events. This work focuses on the coincidence of human error and mechanical failure to introduce a concept of dynamic management of human error. By the dynamic management of human error during a short period, when a mechanical component is temporarily unavailable during periodic testing or maintenance, the probability of a major accident may be reduced significantly without additional investment on improving safety. For the periodically-tested standby component, the majority of total average unavailability of the component may be recognized by operators or workers as well as maintenance mechanics. During this short period, an appropriate dynamic management of human error for improving human performance temporarily may be very effective in reducing total risk in industries. The dynamic management of human error may be a useful method to prevent loss effectively in the process industries

Calculation of Fire and Explosion Index (F&EI) value for the Dow Guide taking credit for the loss control measures

Abstract: The Dow Fire and Explosion Index (F&EI) is universally used in evaluating the hazard category of a process plant, area of exposure, expected losses in case of fire and explosion, etc. In the current procedure, the effects of the loss control measures (LCMs) on the F&EI value are not taken into account. This makes the plant look more hazardous, makes it more spread out, requires more elaborate emergency measures and alarms the public and the civil administration more than is necessary. It also affects the insurance premium. We suggest taking the effects of the LCMs into account in the F&EI value. We call this the ‘Offset F&EI’ value. It favorably affects all the above items, and other related ones. To do this, we have developed the relevant equations and have proved the efficacy of the Offset F&EI by means of an example.

Safety evaluation of engineering and construction projects in China

Abstract: In this paper, we review safety evaluation of engineering and construction projects in China and introduce four safety evaluations that are mostly used in China: safety pre-evaluation (SPE), safety evaluation on project completion (SEPC), overall safety evaluation of current status (OSECS) and special safety evaluation (SSE) Furthermore, related legal and policy trends of safety evaluation in China and the future development are also discussed here

Fire and explosion at mutual major hazard installations: review of a case history

Abstract: In industry, it is common that there are independent but related major hazard installations which compliment each other. The link between the major hazard organizations is an interface between the installations. This interface is a critical area for the mutual major hazard installations. Examples of such organizations are chemical cargo ships and their terminal storage yard, the supply vessels and platforms, floating storage tanks at offshore areas and oil tankers, two offshore platforms tied together etc. This paper summarizes the major accident at M. T. Choon Hong III Ship and Tiram Kimia Sdn. Bhd. (TKSB), and also discusses the causes which led to this major accident. It was found that the lack of integrity is the main cause behind the escalation of the fire and explosion at the Choon Hong III Ship and the TKSB. It was noted that the disaster which involved mutual major hazard installation was preceded by two incubation periods.

Calorimetric behaviors of hydroxylamine and its salts caused by Fe(III)

Abstract: The objective of this study is to obtain information on the calorimetric behaviors of aqueous solutions of hydroxylamine (HA), hydroxylamine chloride (HACl), and hydroxylamine nitrate(HAN) caused by different Fe(III) states (free Fe(III) from Fe(NH 4 )(SO 4 ) 2 , Fe(CN) 6 3− , and Fe(EDTA) − ). The calorimetric data were obtained with a small-scaled reaction calorimeter, Super-CRC. In the mixing with Fe(III), HA showed the highest reactivity among three substrates. Free Fe(III) and Fe(EDTA) − showed catalytic effects in the reactions. In the overall heat of reactions, Fe(EDTA) − exceeded free Fe(III), which precipitated as Fe(OH) 3 and decreased the chances of interactions with HA. It was suggested that the generation of NH 3 had taken place in the process of reducing HA along with Fe(II) oxidation. Fe(CN) 6 3− was less reactive than free Fe(III) and Fe(EDTA) − . The ability of masking Fe(III) was estimated for CyDTA. The HA including CyDTA had no exothermic peak; however, there was an endothermic peak of the heat flow at Fe(III) injection. CyDTA was found to have the ability to inhibit a violent exothermic reaction of HA.

Vented gaseous deflagrations: modelling of translating inertial vent covers

Abstract: A model of explosion pressure build up in enclosures with translating inertial vent covers is presented. The previous approach, valid for inertia-free vents, is advanced by appending to it a new model of translating inertial vent cover displacement. The model and CINDY code are validated against experiments by Hochst and Leuckel (J. Loss Prev. Process Ind. 11 (1998) 89) in a 50-m 3 vessel with vertically translating covers with surface densities of 42 and 89 kg/m 2 at conditions of initially quiescent and turbulent mixtures. It is demonstrated for the first time that modelling of the vent cover jet effect is crucial for prediction of interdependent pressure-time and cover displacement-time transients, whereas air drag force and cushioning effects are negligible. The model was used further to investigate the influence of vent cover surface density on venting generated turbulence, via comparisons with experimental data of Cooper et al. (Combust. Flame 65 (1986) 1) in a 1-m 3 enclosure with vertically translating covers of various surface densities up to 200 kg/m 2 . The increase of the turbulence factor, i.e. total premixed flame front wrinkling factor, with cover inertia is obtained and explained.

High voltage and break spark ignition of propylene/air mixtures at various initial pressures

Abstract: The original break spark test apparatus for intrinsically safe circuits was modified to allow the measurements of minimum ignition currents (MICs) at different initial pressures between 20 and 120 kPa. The MICs of different propylene/air mixtures at ambient temperature and at both atmospheric and sub-atmospheric pressures were measured. The corresponding minimum ignition energies (MIEs) using break sparks were calculated and compared with those derived from MIE/quenching distance correlations using high voltage sparks between flanged electrodes.

The runaway scenario in the assessment of thermal safety: simple experimental access by means of the catalytic decomposition of H2O2

Abstract: The runaway scenario can serve as a basis for the assessment of thermal process risks. In this context, the time to maximum rate ( TMR ad ), i.e., the time between cooling failure and thermal explosion, can be a measure of the time in which safety measures must be taken. This paper highlights the discussion of TMR ad by presenting the catalytic decomposition of hydrogen peroxide with potassium iodide. The experimental procedure is easily practicable and imposing for the students. An overview of the theoretical background is given before presenting the experiment.

Safety analysis and risk assessment in a new pesticide production line

Abstract: In this work, the safety analysis of a new production line in a pesticide factory in Northern Italy is presented. The analysis was based on four different methods in a way that every part of the new line was investigated. The eventual incidents identified by this analysis were further examined with regard to their consequences using three different simulation models for the release and dispersion of the resultant toxic cloud. This analysis has proven that the risk level for the personnel of the factory and the surroundings is acceptable.

Technological disaster factors

Abstract: Major Hazard Installations (MHIs) deal with the hazardous substances which exceed the threshold quantity. Although MHIs are safe organizations, they cannot fail due to a single error. However, due to their high complexity, the designer and the operator make errors during the design, and operation of the plants. Consequently, the technical, operational and organizational errors may lead to a major accident. The world has seen many incidents due to the operation of the MHIs. Malaysia has experienced several technological disasters. Four investigation reports have been reviewed in detail. This paper reviews the causes of the technological disasters in general. This paper also summarizes the causes of the technological disasters in Malaysia. Finally the paper rearranges the technological disaster causes and errors.

Ignition of a dust layer by a constant heat flux

Abstract: In real conditions, the surface temperature of an equipment enclosure covered with a combustible dust layer can significantly rise due to insulating properties of the dust layer. To assess this effect, the measurements of minimum ignition temperature of dust layer at constant temperature of the heated plate t t min (standard method) and the same ignition temperature at constant rate of heat generation t h min for two coal dusts were made. Dust layers of thickness between 5 and 50 mm were tested. For each dust, t t min was higher than t h min for every tested thickness of the layer. The difference was biggest for thin layers and decreased with increase of the layer thickness. The results suggest a deficiency of the standard procedure of measuring minimum ignition temperature of a dust layer.

Study on decomposition of hydroxylamine/water solution

Abstract: The risk evaluation of decomposition of hydroxylamine(HA)/water solution was studied experimentally. The thermal property of HA/water solution was studied from the calorimetric data obtained using the differential thermal analysis (DTA). The intensity of decomposition was studied on the basis of the results of the mini closed pressure vessel test (MCPVT) and the pressure vessel test (PVT) in addition to the steel tube test. The thermal property of HA/water solution was evaluated on the basis of results of the DTA. The heat-release onset temperatures using the no-treated stainless steel cells were more than 70 K below those measured using the GSC. This result implies that the heat-release onset temperature depends on the materials of sample cell. On the other hand, the heat of reaction did not depend on the materials of sample cell. The intensity of the thermal decomposition was investigated on the basis of results of the MCPVT, the PVT and the steel tube test. The intensity of the thermal decomposition increased as the HA concentration increased in the MCPVT. The intensity of the thermal decomposition increased greatly when the HA concentration was beyond 80wt.% in the MCPVT. It was elucidated that the thermal decomposition of HA 70wt.%/water solutions was very violent in the PVT. In addition, HA/water solutions of more than 80wt.% concentration could detonate in the steel tube test. HA 80 wt.% water/solution was easily detonated by a detonator without RDX in the steel tube test. In addition, the decomposition hazard of HA/water solution by the metal ion and the iron powder was studied in this paper. The thermal stability of HA85%/water solution with the iron ion or the iron powder was discussed on the basis of the heat-release onset temperature by the DTA. The heat-release onset temperatures decreased when the concentration of the iron ion or the iron powder increased in the DTA measurements. The reactiveness of HA/water solution with the metal ion of iron, manganese, nickel, chromium and copper was examined by measuring the mass loss of HA/water solution after the metal ion was added to HA/water solution at room temperature. The reactiveness of HA/water solution with the iron powder was also studied in this paper. The ferrous ion, the ferric ion and the iron powder reacted with HA/water solution. Ignition automatically began when the 0.2wt.% ferric ion solution was added to HA85wt.%/water solution. The mass loss rate depended on the HA concentration greater than the iron ion concentration. The mass loss rate increased when an amount of the iron powder increased. On the other hand, the decomposition reaction of HA85wt.%/water solution with Cu2+ was calm compared to that of the iron ion. HA/water solution did not react with Mn2+, Ni2+ and Cr3+ at room temperature.

The multi-energy critical separation distance

Abstract: Devastating vapour cloud explosions can only develop under appropriate (boundary) conditions. The record of vapour cloud explosion incidents from the past demonstrates that these conditions are readily met by the congestion by process equipment at (petro-) chemical plant sites. Therefore, the possibility of an accidental release of a flammable and a subsequent vapour cloud explosion is a major hazardous scenario considered in any risk assessment with regard to the process industries. If an extended flammable vapour cloud at a chemical plant site extends over more than one process unit, which are separated by lanes of sufficient width, the vapour cloud explosion on ignition develops the same number of separate blasts. If, on the other hand, the separation between the units is insufficient, the vapour cloud explosion develops one big blast. The critical separation distance (SD) is the criterion that allows discriminating in this matter for blast modelling purposes. This paper summarises some major results of an experimental research programme with the objective to develop practical guidelines with regard to the critical SD. To this end, a series of small-scale explosion experiments have been performed with vapour clouds containing two separate configurations of obstacles. Blast overpressures at various stations around have been recorded while the SD between the two configurations of obstacles was varied. The experimental programme resulted in some clear indications for the extent of the critical SD between separate areas of congestion. On the basis of safety and conservatism, these indications have been rendered into a concrete guideline. Application of this guideline would allow a greater accuracy in the modelling of blast from vapour cloud explosions.

Economic-statistical design of multivariate control charts for monitoring the mean vector and covariance matrix

Abstract: When a control chart is used to monitor a process, three test parameters should be determined: the sample size, the sampling interval between successive samples, and the control limits or critical region of the chart. In this paper, we present the procedure to conduct the economic-statistical design of multivariate control charts for monitoring the process mean vector and covariance matrix simultaneously; i.e. to economically determine the optimum values of the three test parameters such that the statistical constraints (including the type I error probability and power) of the control chart can be satisfied. The test statistic −2l nL is applied to develop this procedure and the cost model is established based on the function given by Montgomery and Klatt. A numerical example is provided to illustrate the solution procedure of the design and then the effects of cost parameters on the optimal design are examined.