bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel, thermal instability in a ‘semi‐batch’ reactor
Authors: Gray B. F. , Coppersthwaite D. P. , Griffiths J. F.
Published: June 2004

An unusual type of oscillatory, thermal instability in a reaction which takes place in a semi‐batch reactor, (i.e., when one reactant is admitted slowly to the reaction vessel and mixes with another reactant already present in the system) is investigated experimentally and theoretically. We show not only that oscillatory temperature changes may occur that are sufficiently large to constitute a formidable explosion hazard but also that the conditions under which such a hazard may take place could be entered unwittingly, in a mistaken belief that a move away from a potentially hazardous zone is being made. The theoretical background is formulated analytically in the context of a first order exothermic reaction. However, from the experimental study of the exothermic gaseous reaction between hydrogen and chlorine, we confirm the existence of oscillations and we show that the main features predicted by the simple theory transpose to more complex kinetic systems. In this particular system, temperature changes in excess of 200 K were measured in the unstable oscillatory region. The experimental study is linked to the theoretical foundations through numerical modelling of the non‐isothermal process, based on a detailed kinetic mechanism of the H2 + Cl2 reaction. Similar oscillatory phenomena are also shown by numerical simulation to be possible in a semi‐batch reactor in an exothermic reaction between two liquids.
To BLEVE or not to BLEVE: Anatomy of a boiling liquid expanding vapor explosion
Authors: Venart J. E. S. , Rutledge G. A. , Sumathipala K. , Sollows K.
Published: June 2004

The loss of containment (LOC) for Pressure Liquefied Gas (PLG) vessels under accidential fire engulfment is shown to be very complex. The LOC depends upon: (i) the extent and intesity of external heating, (ii) the pressure relief device (PRD) operation and flare (if contents flammable), (iii) the fluid and fill level, (iv) the construction of the vessel, and (v) the thermohydraulic history of the commodity prior to failure.

The Simple experiments described here shows that there exists a new type of more powerful failure than the BLEVE. This even we call a BLCBE, a Boiling Liquid Compressed Bubble Explosion. A hypothesis is advanced to explain this mode of failure which is supported by an initial series of small scale experiments involving Argon, water, R11, and R123.

A comprehensive test program to determine the details of the BLCBE and BLEVE failure modes is indicated along with work to determine methods of protection.
Industry views on chemical process safety
Authors: Andrews David C.
Published: June 2004

The American Petroleum Institute strongly supports process safety management (PSM). However, as we begin to implement OSHA's new PSM rule, and as we face EPA's Risk Management Plan Rulemaking pursuant to the Clean Air Act Amendments, we have several concerns. These involve: (1) resource management; (2) quality of effort; (3) managing regulatory change; (4) enforcement; (5) prospect of duplicative or inconsistent regulations; and (6) role of the Chemical Safety Board. An enormous challenge lies ahead for industry, consultants and contractors, as well as OSHA and EPA, in implementing process safety management. Working together, we will be successful.
Systems for good management practice in quantified risk analysis
Authors: Jenssen Tore K.
Published: June 2004

Audit systems for quantifying the quality of safety management are discussed, as well as lessons learned from European R&D in developing correction factor for good management practices in quantified risk analysis. It also describes how internal process safety audits help quantify strengths and weaknesses.
The unforeseen side‐effects of improving the environment
Authors: Kletz Trevor A.
Published: June 2004

Changes made to improve the environment have sometimes produced unforeseen and hazardous side‐effects. Thus enclosing compressor houses to reduce noise has made explosion more likely, the replacement of CFCs in aerosols has led to a number of fires in plants and warehouses and the confinement of flammable vapors in vent collection systems has caused a number of explosions. These and some other similar changes are described. Before changing designs or methods of operation we should try to foresee their effects and we should balance the risks to people against the risks to environment.
Vapor suppression of chemicals using foams
Authors: Scheffler Norman E. , Green L. Shayne , Frurip David J.
Published: June 2004

In the handling of chemicals in our plants, there is always concern about the possibility of spillage. The consequences of a spill have to be carefully evaluated. Two of the main hazards are fire and emissions to the environment. Foams have proven to be very effective in blanketing a spill and in giving fire extinguishment by providing a barrier covering. This same barrier covering can also be effectively used to suppress vaporization and emissions. This paper gives the results of measurements of the vapor suppression for various chemicals using foamsm, and gives the test procedures developed. The base conditions simulated a 5.0 mph (8.05 km/hr) wind at 25°C with a 76% relative humidity, using Universal® GOLD foam from Chubb National Foam. Variables studied were chemical, foam type, foam height, relative humidity, and time. Data was obtained for chemical concentration in the vapor and relative percent vapor suppression versus time using acrylonitrile, ethyl acrylate, butyl acrylate, methyl methacrylate, allyl chloride, propylene oxide and vinylidene chloride. Excellent vapor suppression was demonstrated for most systems with 100% vapor suppression for 2 hr for vinylidene chloride, about 95% for 2 hr for the acrylates and allyl chloride, and 90% for 2 hr for acylonitrile. Propylene oxide was suppressed to 95% for 1 hr before marked decrease.
Compliance strategies that work
Authors: Auger John E.
Published: June 2004

OSHA's regulation 1910.119, Process Safety Management of Highly Hazardous Chemicals, is having a significant impact on the affected industries. It's probably an understatement to say that industry has struggled to implement process safety management systems to comply with the regulation.
Electrostatic ignitions in enriched oxygen atmospheres: A case history
Authors: Pratt Thomas H.
Published: June 2004

There have been instances where ignitions have occurred in oxygen enriched atmospheres in closed systems. The causes of these ignitions have been difficult if not impossible to explain by ordinary mechanisms, and even though electrostatics has been implicated, there have been no definitive mechanisms proposed which can explain the ignitions. This paper will perhaps be a step toward a satisfactory explanation by bringing another electrostatic mechanism to the attention of the loss prevention community.

In an example incident, ignition occurred when oxygen was bubbling to the surface of a liquid where flammable vapors existed. It is known that bubbles breaking at a liquid surface can create an electic field in the atmosphere above the liquid. Also, in real systems, there are all sorts of surface discontinuities and things floating about so that there are sharp points where it is conceivable that corona discharge may develop, depending on the strength of the electrostatic field. In ordinary atmospheres, corona discharge is only incendive to very sensitive vapors and is considered to be non‐incendive to ordinary vapors, but on the other hand, it is well known that the minimum ignition energy requirements for ordinary vapors in pure oxygen atmospheres are some 100 times less than those in normal atmospheres. Such a reduction in energy requirements could likewise be expected for corona discharge. One can then speculate that such a self induced corona discharge could have been capable of igniting the flammable vapors which were in an oxygen enriched atmosphere. The experimental and theoretical pros and cons of this mechanism are discussed in the paper with no definitive conclusion being reached.
Evaluating external spill response resources
Authors: Browne George
Published: June 2004

Imagine that a seemingly minor fire has been discovered in the warehouse storing raw materials for your plant. The fire department is notified and you expect that the emergency will be over shortly. Twelve hours and several millions dollars worth of damage later, the fire is extinguished. You stand there in shock as you try to make sense of what happened. Reality or fiction? The answer can depend on many factors, some of which you can resolve, easily, and some which will require an extensive commitment of time and money.
Failure and design limit criteria for blast loaded structures
Authors: Barker D. D. , Whitney M. G. , Waclawczyk J. H.
Published: June 2004

The majority of buildings located at petrochemical plants, exclusive of control rooms, are of conventional construction and do not explicitly provide for resistance to blast loads. Typical construction types include steel frame with metal cladding, concrete masonry unit, and brick clad with concrete or steel frame. These buildings are designed for conventional loads without regard for high overpressures and fragments resulting from an accidental explosion. Current regulatory trends are causing many companies to evaluate design standards for new and existing support structures especially in the wake of recent accidental explosions. Response criteria is an important part of these design standards especially when they are used to analyze existing structures for blast protection. Structural evaluations at several sites have revealed that few existing structures meet current design criteria primarily due to weak member connections. Previous work has shown that many conventional structures can develop a surprising degree of resistance to blast loading if proper detailing is used in design, thus allowing members to develop their full capacity. This paper discusses response criteria currently used for new structures and examines the problem of determining acceptance criteria for existing structures. Data from explosion accidents and test programs is reviewed to determine the degree of conservatism in current criteria. Finally, alternatives for establishing blast capacity of existing structures are discussed.
The cost and benefits of process safety management: Industry survey results
Authors: Bridges William G.
Published: June 2004

Process safety management (PSM) is a relatively new phrase that encompasses many activities for controlling process‐related hazards in the workplace. These activities (also called PSM elements) have been maturing at different rates over the past two decades. Since 1986, state and federal regulators have been mandating implementation of PSM programs at workplaces that handle hazardous chemicals, including explosives, toxics, and flammables. Before promulgating their regulations, the regulators estimated the cost and benefit of compliance with these regulations, but in all cases their cost estimates have fallen orders of magnitude short of actual implementation costs. This paper presents the actual costs that some companies have expended and provides estimates of future costs to comply with either self‐imposed standards or government regulations related to PSM. The data on actual costs were provided in response to a recent survey. The costs are broken into categories so that companies just now implementing PSM will be able to gear up for their future efforts. Also discussed are the types of benefits and, where possible, the actual benefits that have been achieved by implementing PSM programs. The cost of developing and implementing PSM is great; however, most companies have seen comparable or greater benefits as a result of implementing PSM programs. Finally, this paper explores the cost of implementing EPA's forthcoming regulation for risk management programs.
Prediction of discharge rate from pressurized vessel blowdown through sheared pipe
Authors: Khajehnajafi Shahryar , Shinde Ashok
Published: June 2004

It is a common industrial practice to store chemicals in large vessels. For emergency response management, prediction of the impacted area due to the dispersion of a chemical accidentally released from a vessel is crucial. Therefore, accurate estimation of the release rate and condition of the flowing stream is warranted.

Based on this need, a general purpose quasi‐steady model is developed which can calculate the discharge rate from a tank‐pipe system (rupture in the tank or shearing of an attached pipe). The tank may contain gas, vapor, saturated or sub cooled liquid (under its own vapor pressure or padding pressure). The model output includes the history of the tank variables i.e., pressure, temperature, mass content, liquid level as well as the transient outflow of chemicals from a rupture or pipe as a function of momentary tank thermodynamics condition. The results of the model for the case of two phase flow through a pipe are validated against experimental data. Charts are provided which show the effect of the pipe length and the padding pressure on the discharge of the tank content.
Quantitative evaluation of fireball hazards
Authors: Prugh Richard W.
Published: June 2004

Fireballs from BLEVEs and flash fires resulting from delayed ignition of spills can cause injury to nearby personnel and damage to exposed property. The consequences of accidental BLEVEs and spill fires are compared with theoretical models for evaluating the effects of thermal radiation.
Loss case histories in pressurized ethylene systems
Authors: Britton Laurence G.
Published: June 2004

This paper addresses a number of accident case histories in pressurized ethylene systems comprising heaters, driers, purifiers and High Pressure Polyethylene product receivers. Also covered are compression‐heating accidents in pipelines and compressors, and decomposition via external fire exposure of piping.

Several companies contributed accounts; few of these have been reported in the open literature. The probable event scenarios are discussed with reference to safety information that in many cases postdates the contemporary loss reports. While there may be room for some debate over probable causes, insight can be gained simply by reading the accounts.

The objective is to provide real examples of design and operational oversights contributing to preventable losses. As usual in Loss Prevention case histories, an important lesson is that years of uneventful operation often pass before a problem is recognized, and that subsequent investigation often uncovers the potential for other failure routes and possibly worse outcomes.
Application of ARCTM thermokinetic data to the design of safety schemes for industrial reactors
Authors: Townsend D. I. , Ferguson H. D. , Kohlbrand H. T.
Published: June 2004

An ARCTM or similar experimental apparatus provides the transient temperature history of a chemical system under adiabatic conditions. The information obtained has several applications in the design and operation of industrial systems. Of particular interest is use of the adiabatic kinetic data to define “intervention strategies” based on “allowable response times” during an emergency.

The time‐temperature behavior of industrial reactors can be simulated over a limited temperature range by matching the “thermal inertia” (or ϕ‐factor) of the experimental system to that of the full‐scale system. This approach is applicable even for complex reactions, minimizes the extrapolation of data, and allows the use of simple models for data interpretation. Simulation results directly give the time available to respond in the event of a thermal runaway; this in turn defines the design requirements for an intervention scheme (e.g., emergency cooling, blow down, quench, etc.). The chosen intervention system can be tested experimentally prior to and/or during process start‐up.
Validation of scaling techniques for experimental vapor cloud explosion investigations
Authors: Mercx W. P. M. , Johnson D. M. , Puttock J.
Published: June 2004

Within the project “MERGE”, an acronym for Modelling and Experimental Research into Gas Explosions, eight institutes from five different European countries co‐operated to increase the understanding of vapor cloud explosions and to improve the sophisticated computerized prediction techniques that were, until this project, under separate development at several institutes.

The objectives of the project were:

to provide a consistent set of data on the influence of obstacles on flame propagation in initially quiescent mixtures at various geometrical scales;

to improve, compare and validate numerical models for vapor cloud explosion simulation;

to validate scaling techniques for explosion experiments;

to investigate and to model jet explosions.

The second item is discussed in this report.
Transition from deflagration to detonation in layered dust explosions
Authors: Sichel M. , Kauffman C. W. , Li Y. C.
Published: June 2004

Dust layers on the bottom of mine tunnels, on factory floors, or on the floors of grain elevator passages are the most frequent cause of highly destructive dust explosions. Typically, such layered dust explosions involve a high velocity, accelerating, turbulent flame which is fed by the dust layer and results in high destructive static and dynamic pressures. In some cases transition to detonation has been observed, and such explosions are the most destructive. Scientific studies of such layered dust explosions, conducted at the University of Michigan, are discussed.
Some loss prevention case histories
Authors: Kletz Trevor A.
Published: June 2004

We learn more from accounts of accidents than from codes and standards or exhortations to follow them. Incident reports are more likely to spur us into action. We are unlikely to read a code until an accident report has shown us the need. This paper describes a number of accidents, some old, some recent, which can teach us lessons of general interest. It looks at the underlying causes as well as the immediate technical ones.
Measures for reducing SCC in anhydrous ammonia storage tanks
Authors: Nyborg Rolf , Lunde Liv
Published: June 2004

The results from four research projects on ammonia stress corrosion cracking (SCC) are provided, including the effect of oxygen and water in the ammonia, prevention of SCC with electrochemical methods, crack growth rate studies, and behavior of welds. Practical recommendations are given for construction, inspection, repair, commissioning, and operation of ammonia storage tanks.
The sensitivity of non‐explosive compounds to friction testing
Authors: Négyesi György
Published: June 2004

Process safety officials often place great emphasis on the results from tests to define various fire and explosion hazards inherent in dusts. These include the flammability, the autoignition temperature, the lower explosive limit, and sometimes the Kst‐value which is a characteristic equivalent to the maximum pressure rise in a 1 m3 vessel of an optimally combined substance/air mixture when the temperature is 20°C and pressure was 100 kPa before the explosion. It is also important to know if there is any electrostatic hazard. Tests of the specific volumetric resistance, the minimum ignition energy, the electrostatic chargeability, the relative permittivity and the discharge time contribute to determining this specific hazard.

If the substance is also subjected to elevated thermal conditions, the safe process temperature should be tested by the help of thermoanalytical techniques [1, 2, 3, 4]. If the dust indicates the characteristics of an explosive in such tests, its sensitivity to impact should be tested, and if the substance is sensitive to impact, its sensitivity to friction should also be tested [5, 6, 7]. Note: many of the tests used for process safety studies in the chemical industry have been adapted from the explosives industry.

The significance of friction testing for expert decisions regarding grinding operations on non‐explosive chemicals when the test results of the sensitivity to impact were negative is introduced in this paper.
Vapor cloud explosion analysis
Authors: Baker Quentin A. , Tang Ming Jun , Scheier Ephraim A. , Silva Gustavo J.
Published: June 2004

This paper introduces a new method (now commonly referred to as the Baker‐Strehlow Method) for estimating pressure and impulse generated by vapor cloud explosions. Strehlow's blast curves and concepts from the Multi‐Energy method for determination of explosion energy are applied in this technique. New correlations for maximum flame speed based on obstacle density, fuel reactivity, and cloud confinement allow selection of the appropriate blast curve. Application of these correlations removes much of the subjectivity present in existing explosion estimates.
On the estimation of hazard potential for chemical substances
Authors: Melhem G. A. , Shanley E. S.
Published: June 2004

There is considerable interest in means for predicting reactivity hazard potential from chemical structure. Such means are intended to provide measures of the likelihood that a given chemical composition can undergo rapid self‐reaction, i.e., that it can detonate or deflagrate. The means to be discussed are most useful in predicting behavior under unconfined conditions. As they are computational in nature, they can be deployed quickly and easily to wide ranges of compositions, whether or not these have ever been made. Comparison with better‐known compositions is facilitated and can provide additional guidance.

In this paper we provide critical reviews of some commonly used hazard evaluation systems, including the oxygen balance system, and ASTM CHETAH. We also provide a review of our recent studies aimed at the development of more powerful screening systems.
Hazard rating system for flammable and combustible liquids
Authors: Scheffey Joseph L. , Tabar David C.
Published: June 2004

Flash point determinations made from small‐scale fire test apparatus are used by regulatory authorities to classify flammable and combustible liquids. Based on these classificaiton, regulators then specify or provide guidance on the appropriate methods to transport, handle, package, store, dispense, and protect these materials. Closed‐cup flash points of flammable and combustible liquids are used to establish their appropriate classification. Exceptions to these classifications include products such as alcoholic beverages and medicines stored in relatively small containers, which have historically presented a limited fire hazard.

Many companies are now reformulating their consumer liquid products to meet customer and regulatory demands for low volatile organic compounds (VOC's). Low VOC formulations often do not inherently result in the total elimination of flammable or combustible liquid solvents. In some cases, the reformulations result in “water‐reducible” products, which contain a high water content. Water‐reducible coatings are products where the solvent system used to disperse and suspend solids is primarily water. The remainder of the solvent system may contain liquids that are classified as flammable or combustible liquids. A natural by‐product of the “water‐reducible” trend is the development of a fire analysis framework which could be adopted by regulatory authorities as part of the movement toward performance‐oriented codes. This methodology could also be used to address limitations of specific test methods. These limitations relate to product vicosity, accuracy in predicting overall fire hazard, ability to assess physical changes of state when a product is tested, and test method reliability and ease of use.
Pipe and duct deflagrations associated with incinerators
Authors: Chatrathi Kirs , Going John
Published: June 2004

The potential for dust and gas explosions in the process industries has been long recognized. Potentially explosive materials are handled in large quantities on a daily basis. A specific hazard associated with conveying materials into incinerators and thermal oxidizers involves the potential for deflagration propagation through process pipes and ducts back into the plant.

The deflagration propagation phenomena in pipes and ducts is one that is both highly hazardous and complex to predict. A deflagration, moving down a pipe, under the right conditions can increase in velocity to the point when a transition into detonation occurs with potentially catastrophic results. This deflagration to detonation transition (DDT) is effected by a number of interrelated factors. Knowledge of these factors is crucial to the development of explosion prevention and protection measures.

A discussion of the deflagration phenomena is presented with emphasis on pipes and ducts and transition of deflagration to detonation. The use of this information to design explosion protection is described using several industrial examples.
Reaction calorimetry for process development: Recent advances
Authors: Singh Jasbir
Published: June 2004

Reaction calorimetry has found widespread acceptance as a valuable tool that provides a combination of thermal hazard and process data for batch‐type reactors. There have been many significant advances in this type of instrument over the last few years, which include both improvements in methodology and the addition of new experimental features. This article describes, with examples, the basic elements of a reaction calorimeter, comparison of commercial devices, and a number of new development, including the use of power compensation in place of the more familiar heat flow calorimetry.

Applications to process safety and reaction optimization are presented with data from the SIMULAR reaction calorimeter.
Measuring inherent safety, health and environmental characteristics early in process development
Authors: Hendershot Dennis C.
Published: June 2004

It is generally agreed that inherent safety is most effectively addressed early in chemical process development. Measurement of inherent safety, health, and environmental (SHE) characterisics of various process alternatives is important to effectively consider these charactersitics when selecting the best overall process. Several tools which can be used to measure inherent SHE characteristics of a chemical process early in development are briefly discussed.
The explosion blast prediction model in the revised CPR 14E (yellow book)
Authors: Mercx W. P. M. , van den Berg A. C.
Published: June 2004

The well‐known Yellow Book, nickname for the publication by the Dutch Ministry of Social Affairs and the Environment contains a number of models for prediction of the effects following an accidenial release of hazardous materials. TNO was involved in a complete revision of this Yellow Book. One of the models that has been completely revised is the blast prediction model for vapor cloud explosions. The Multy‐Energy model was selected as the new model to be incorporated in the revision. The concept of the Multy‐Energy model is widely accepted as a better alternative to TNT equivalence methods although a practical application is hampered by a lack of guidance for application in practice. Guidance for application is given in the revision, though it still leads to conservative solutions.

This paper describes how the method should be applied according to the revised Yellow Book. The motivation for the guidance for application given is discussed by comparison with guidance given in other publications and with experimental results obtained from some large scale experimental programs. Present efforts in an ongoing research program by TNO to obtain more detailed and sound guidance is presented as well.
A detailed method for estimating mixture flammability limits using chemical equilibrium
Authors: Melhem G. A.
Published: June 2004

This paper presents a general method for the estimation of flammability envelopes for chemical mixtures based on chemical equilibrium. The impact of mixture initial temperature, the presence of diluents and elevated system pressures are implicitly accounted for. The performance of this method is tested against much of the experimental data reported in the literature for systems containing a wide range of chemicals from CHNO compounds to compounds containing sulfur, phosphorus, silicon and halogens.

This method presents a very useful and accurate approach for assessing the flammability envelopes of mixtures where no experimental data is available, and to guide experimental flammability testing work.
Burst resistant ribbon wound pressure vessels for ammonia plants
Authors: Shah Manesh , Zhu Guohui
Published: June 2004

This paper presents the design of ribbon wound pressure vessels useful for Ammonia, Urea and Methanol plants. The design is to create a thin shell of 1/5 the total wall thickness required, weld it to the end pieces, and wind 4 to 8 mm thick ribbons of 80 mm width at an angle of 15 to 30 degrees on the inner shell, using a prestress. The ribbons are welded at the ends and an even number of layers are wound cross‐helically on to the shell. With more than 7000 vessels over the pressure range of 50 to 350 atmospheres in use in the various chemical industries in China over the past 30 years, their safety record has been excellent. Of particular interest has been the application of this technology in the Ammonia and Urea plants, where the design allows fabrication of these vessels at substantial reduction in cost, and early delivery, when compared to the mono wall technology.
Models for domino effect analysis in chemical process industries
Authors: Khan Faisal I. , Abbasi S. A.
Published: June 2004

In the risk assessment parlance, especially with reference to chemical process industries, the term “domino effect” is used to denote “chain of accidents,” or situations when a fire/explosion/missile/toxic load generated by an accident in one unit in an industry causes secondary and higher order accidents in other units. The multi‐accident catastrophe which occurred in a refinery at Vishakhapatnam, India, on September 14, 1997, claiming 60 lives and causing damages to property worth over Rs 600 million, is the most recent example of the damage potential of domino effect.

But, even as the domino effect has been documented since 1947, very little attention has been paid towards modeling this phenomena. In this paper we have provided a conceptual framework based on sets of appropriate models to forecast domino effects, and assess their likely magnitudes and adverse impacts, while conducting risk assessment in a chemical process industry. The utilizability of the framework has been illustrated with a case study.
Multivariate hazard identification and ranking system
Authors: Khan Faisal I. , Abbasi S. A.
Published: June 2004

Risk analysis in chemical process industries is an elaborate exercise involving several steps from preliminary hazard identification to development of credible accident scenarios, to preparation of strategies for prevention or control of damage.

All this requires substantial inputs of time and money. In order to get an approximate yet workable assessment of risk at much lesser costs, indices have been developed which link typical findings of elaborate risk analysis to scales of risk. The scales, in turn, provide workable measures of hazards/risks/safety.

In the past, indices have been reported for swift risk assessment—the noteworthy among them include Dow fire and explosion index, Mond fire, explosion and toxicity index, IFAL index, and mortality index. A few rapid ranking techniques have also been proposed.

This paper presents a new system of methodologies for Hazard Identification and Ranking (HIRA). The system consists of two indices: one for fire and explosion hazards and another for the hazard due to likely release of toxic chemical. The magnitudes of these indices indicate the severity of the likely accident; in terms of the size of the impacted area.

HIRA has been applied to a typical chemical process industry—a sulfolane plant—and its performance has been compared with that of the Dow's and the Mond's indices. The study reveals that HIRA is more sensitive and accurate than the other indices.
Reactivity and ignition characteristics of silane/air mixtures
Authors: Tamanini Francesco , Chaffee Jeffrey L. , Jambor Richard L.
Published: June 2004

Research was carried out to develop improved protection guidelines for silane handling systems through enhanced understanding of the behavior of releases of this pyrophoric gas. The approach involved addressing three aspects of the problem: the prompt ignition behavior of silane; the reactivity characteristics of quiescent silane/air mixtures; and the rates of reaction of silane leaked into enclosures with and without explosion venting, in the presence of ventilation air flow. A first conclusion, reached from tests in a ventilated cabinet, was that, contrary to prevailing belief, the ventilation flow has no measurable effect on the prompt ignition of the release. From experiments in a 5.1‐liter (311‐in.3) sphere it was found that silane/air mixtures of concentrations between 1.4 and 4.1% (by volume) are explosive but stable. In this case, piloted ignition tests yielded laminar burning velocities up to 5 m/s (1000 ft/min). Mixtures between 4.5 and 38% (the maximum reached in the tests) were found to be metastable, and would undergo spontaneous ignition after a delay ranging from 15 to 120 seconds, with the shorter values corresponding to higher silane concentrations. Experiments were also performed in a 0.645‐m3 (22.8‐ft3) vessel both with and without explosion venting, to measure the rates of energy release associated with impulsively‐started silane leaks from 1/8 and 1/4‐in. (3.2 and 6.4‐mm) lines. A method for the prediction of the venting requirements of partial‐volume deflagrations (PVD) was evolved into a tool to quantify the pressure rise from ignition of silane leaks in enclosures. These results represent a significant step toward updating existing design recommendations which prescribe ventilation requirements that are based on outdated and, in some instances, misinterpreted data.
Properties of simulated gas explosions of interest to the structural design process
Authors: Høiset S. , Hjertager B. H. , Solberg T. , Malo K. A.
Published: June 2004

Gas explosion simulators are often used as tools in process plant design. This article presents some properties of gas explosions found using the EXSIM simulation software on three offshore modules with a total of nearly 10,000 simulations. The selected results are chosen for their supposed applicability to structural design in the process industries.

Generalized data are presented for the effect of gas cloud size, explosion impulse vs. explosion pressure, pressure and impulse vs. duration, the probability of a “short” explosion, loading rate, pressure‐time “shape” function, and the effect of introducing louvers.
Measures taken to ensure safe operation of an ammonia storage tank
Authors: Walter M. , Lesicki R.
Published: June 2004

An ammonia storage tank was built at the BASF Antwerp site in 1969 on land reclaimed from the sea. After several years of operation uneven foundation settlement, of up 2, occurred. In order to assure stability of this area for the next operation period (at least 10 years) measures were taken to ensure continued safe operation. One key measure was strain gauge monitoring at the location of maximum stress.
Recent developments in the Baker‐Strehlow VCE analysis methodology
Authors: Baker Quentin A. , Doolittle Craig M. , Fitzgerald Gary A. , Tang Ming Jun
Published: June 2004

The Baker‐Strehlow methodology was developed to provide an objective approach to prediction of blast pressures from vapor cloud explosions. The complete methodology was first published in 1994 [1]. Since then, it has evolved through ongoing research and use in VCE hazard analyses, facility siting studies and accident investigations. This article gives a brief overview of a paper on recent developments in the Baker‐Strehlow methodology presented at the 31st Loss Prevention Symposium in Houston on March 9‐13, 1997. Because the entire paper is too lengthy to be presented here, the following discussions may be lacking in some details. A copy of the complete paper can be obtained from the American Institute of Chemical Engineers (AIChE).

Since the Baker‐Strehlow method was first published, it has been used extensively in VCE hazard assessments in refineries and chemical plants. As expected, many practical lessons have been learned during the course of the hazard assessments, and the Baker‐Strehlow method has evolved as a result. The changes have been evolutionary, not revolutionary. In keeping with the goals of the original study in which the methodology was developed, all changes have been incorporated with the intent of achieving an objective methodology to provide consistent prediction of VCE blast effects.

The revisions to the Baker‐Strehlow method resulting from experience gained during plant walk‐downs and hazard assessments include:

Systematic identification of “potential explosion sites” or “PESs,”

Selection of the level of confinement for mixed zones of 2D and 3D confinement,

Deciding on flame expansion when confinement is elevated above the vapor cloud,

Selecting the reactivity for a fuel that is a mixture of fuels with differing reactivities,

Predicting blast loads when there are multiple PES's within a vapor cloud considering different ignition source locations.
Equations for the VDI and Bartknecht nomograms
Authors: Simpson L. L.
Published: June 2004

Newly developed equations offer convenience in computer‐aided design of pressure‐relief devices.
Contribution of low‐level flammable vapor concentrations to dust explosion output
Authors: Dahn C. James , Ashum Madelyn , Williams Karen
Published: June 2004

As a result of extensive dust explosion research, additional areas of hazards have arisen. The potential of combining small percentages of flammable vapors (below the lower explosion limit) introduces additional dust explosion hazards.
Corrosion of a CO2 absorber tower
Authors: Kolff S. W.
Published: June 2004

Because of corrosion, the CO2 absorber was lines with stainless steel shingles after 10 to 15 years of operation.
Metallurgical examination of existing piping in an ammonia plant
Authors: Bowen J. Michael , Campbell James D.
Published: June 2004

Based on their previous problems and recent experiences at other ammonia plants, Columbia Nitrogen decided to inspect all high alloy piping containing hydrogen to determine if proper metallurgy had been used in piping and welds.
Heat transfer oil boilers
Authors: Sheehan Edward
Published: June 2004

When properly inspected, operated and maintained, heat transfer oil boilers are safe and reliable.
Investigation and repair of an auxiliary boiler explosion
Authors: Davis Gerald D.
Published: June 2004

On August 1, 1985, an accident occurred at Triad Chemical damaging portions of the primary reformer. The accident was caused by ignition of natural gas pockets which entered the system during attempts to light an auxiliary boiler burner.

The article reviews the cause of the accident, the resulting damage, the required repair, and the modifications made to prevent a recurrence.
Computer room risk assessment
Authors: Barry Thomas F.
Published: June 2004

Large computer systems have become pervasive in today's “Information Society.” In airlines, banking, telecommunications and many other businesses, the computer system provides the competitive edge. The risk of damage to either equipment or data or both has become a vital concern.
Performance of low pressure explosion vents
Authors: Swift Ian , Epstein Mike
Published: June 2004

The internal pressure developed during deflagrations in low‐pressure structures depends on the dynamic performance of the explosion vents used for protection. Large scale tests were performed to evaluate the effectiveness of different types of commercially available vents.
Ammonia converter operation
Authors: Shimagaki Makoto , Miyashita Kenjiro , Ilyas Alita , Kalyubi Aslam
Published: June 2004

Optimization for the operating conditions of Kellogg's four‐stage adiabatic quench converter was achieved in a 1000 MTPD plant of Asean Aceh Fertilizer in Indonesia by adjusting the temperature profile through the catalyst beds with adjustments of quench flows.
Using robots to reduce personnel radiation exposure at the savannah river plant
Authors: Taylor R. Monty , Lewis W. Ivan
Published: June 2004

The Savannah River Laboratory is using robots to improve safety and reduce personnel radiation exposure in the nuclear process environment. This paper reviews several successful applications at this site. A detailed discussion is presented on an application to transfer materials in a line of shielded radiation work cells.
The use (and misuse) of bonding for control of static ignition hazards
Authors: Mancini R. A.
Published: June 2004

In this paper, specific procedures to minimize potential hazards related to the accumulation of static electricity are addressed. The hazards of concern herein are those arising from the ignition of mixtures of air and flammable gases, vapors, and dusts. Accordingly, concerns related to process operability, sensitivity or reliability of electronic components, or nuisance effects are not considered. Also, ignition of condensed phase explosives or oxygen enriched systems are not specifically included through many of the principles and conclusions discussed below will apply.
Static electricity and plastic drums
Authors: Rosenthal Louis A.
Published: June 2004

The use of plastic drums in handling flammable materials require special considerations because of potential static electricity hazards. Various aspects of the problem are presented with suggested means of control.
Static hazards of drum filling. I. Actual incidents and guidelines
Authors: Britton Laurence G. , Smith Jack A.
Published: June 2004

To safely fill drums with flammable liquids of low conductivity, bonding and grounding may not always be enough. Static discharges may under certain conditions originate from charged liquid in the drum, unaffected by grounding. The problem is discussed with reference to actual incidents, published Guidelines, and the types of static discharges that may occur.
Ignition capabilities of hot surfaces and mechanically generated sparks in flammable gas and dust/air mixtures
Authors: Bartknecht W.
Published: June 2004

Flammable gas‐and‐dust explosions may be averted through preventive explosion protection, or the consequences of such explosion may be limited to an acceptable level with design measures [1].
Vent heights for emergency releases of heavy gases
Authors: Bodurtha Frank T.
Published: June 2004

A method to estimate vent heights for emergency releases of heavy gases to prevent flammability at exposed locations has been developed.
Overview of industrial drying needs and competing technologies
Authors: Holmes J. G. , Hedman B. A. , Salama S. Y.
Published: June 2004

Solids drying occurs throughout industry. The types of products dried vary significantly in size, shape, and stability. As a result, a wide range of technologies are used to dry industrial products.
Fires and explosions of hydrocarbon oxidation plants
Authors: Kletz Trevor A.
Published: June 2004

A review of fires and explosions in hydrocarbon oxidation plants, including these caused by decomposition.
Health and safety aspects of thin‐film photovoltaic cell manufacturing technologies
Authors: Fthenakis V. M. , Moskowitz P. D.
Published: June 2004

Production of thin‐film photovoltaic cells entails extensive handling of toxic and flammable, or explosive materials. Large scale manufacture of these photovoltaic cells may present potential health and safety hazards to workers and the public. Hazards to occupational and public health related to the toxicity and explosiveness of several feedstock gases are evaluated and safety and control options are presented.
Emergency relief considerations under segregation scenarios
Authors: Leung J. C. , Stepaniuk N. J. , Cantrell G. L.
Published: June 2004

Emergency venting and containment requirements are considered for segregation conditions leading to massive accumulation of unreacted materials in process vessels. This study points out the importance of considering off‐normal stoichiometry in these upset scenarios.
Explosion in a nitric acid tail gas duct
Authors: Lawrence Garth M.
Published: June 2004

This article relates the events leading to an explosion in the tail gas duct exit the expander, the probable explanation which allowed the formation of nitrites and the steps taken to ensure future safe operation.
The DIERS users group: A forum for development/dissemination of emergency relief system design technology
Authors: Fisher Harold G.
Published: June 2004

DIERS was formed in 1976 to develop methods for the design of emergency relief systems capable of handling runaway reactions [1, 2]. Of particular interest at the time were when tow‐phase flow venting would occur and the applicability of different methods for sizing emergency relief systems for two‐phase, vapor‐liquid flashing flow. Approximately $1.6MM was devoted to investigations of two‐phase, vapor‐liquid onset/disengagement dynamics and the hydrodynamics of emergency relief systems.
Ammonia plant prolonged operation between major overhauls
Authors: Kershaw R. , Cullen J. G.
Published: June 2004

High labor, capital equipment, and variable costs, together with lethally expensive downtime have made ammonia producers seek ways of extending their production runs between major overhauls. This paper outlines operating and maintenance policies together with some of the actions taken at the Kemira (formerly UKF Fertilizers) Ince plant to achieve this objective without compromising plant safety.
A new release of the ASTM CHETAH program for hazard evaluation: Versions for mainframe and personal computer
Authors: Frurip David J. , Freedman Eli , Hertel George R.
Published: June 2004

CHETAH, which stands for the Chemical Thermodynamic and Energy Release Program, was introduced in 1974. Since then, the CHETAH program has been widely used in the chemical industry for hazard evaluation. Although its chief aim is to predict deflagration/detonation potential from molecular structure, it can also be used to estimate heats of reaction, heat capacities, and entropies. One of the limitations of the original program was its rigid, punched card oriented format for data input and the lack of an overall hazard rating derived from the several hazard criteria. A new release of this program alleviates these shortcomings and includes other improvements. The main features of the new release are: 1) a totally interactive front end, 2) an interpreter subroutine which uses sophisticated pattern recognition techniques to combine the four hazard criteria into an overall hazard rating, 3) recognition of certain atomic groupings which are known to be sensitive, 4) correct handling of the symmetry number, and 5) an updated data bank. One of the most important features of this release is its availability in an IBM PC compatible version, making the program accessible to more users.
Dust explosion venting for dusts pneumatically conveyed into vessels
Authors: Siwek Richard
Published: June 2004

The size of venting areas of containers in dust explosions has hitherto been calculated by use of nomograms developed from tests in which explosible dust‐air mixtures were produced by rapid discharge of combustible dust from storage containers. Such tests did not truly reflect the conditions prevailing when containers are charged with product in industrial practice. There was, therefore, a need to perform dust explosion tests with vented containers and pneumatic product filling. The results of such tests show that there is a considerable reduction in the venting area in comparison with that predicted from results obtained with earlier test procedures.