bluuebunny/crossref_metadata_2025 huggingface dataset:
A finite element porothermoelastic model for dual‐porosity media
Authors: Nair R. , Abousleiman Y. , Zaman M.
Published: June 2004

An existing dual‐porosity finite element model has been extended to include thermo‐hydro‐mechanical coupling in both media. The model relies on overlapping distinct continua for the fluid and solid domains. In addition, conductive and convective heat transfers are incorporated using a single representative thermodynamics continuum. The model is applied to the problem of an inclined borehole drilled in a fractured formation subjected to a three‐dimensional state of stress and, a temperature gradient between the drilling fluid and the formation. A sensitivity analysis has been carried out to study the impact of thermal loading, effect of heat transport by pore fluid flow and, the effect of parameters of the secondary medium used to represent the fractures. Copyright © 2004 John Wiley & Sons, Ltd.
Guest–host chemistry with dendrimers: Stable polymer assemblies by rational design
Authors: Pittelkow Michael , Christensen Jørn B. , Meijer E. W.
Published: June 2004

A new type of guest has been designed and synthesized for the exo‐type supramolecular functionalization of adamantyl‐urea‐terminated poly(propylene imine) dendrimers. This new type of guest motif features a uriedo methane sulfonic acid moiety that binds very selectively to the surfaces of dendrimers via a combination of noncovalent interactions forming well‐defined complexes. The guest–host properties have been examined for a fifth‐generation adamantyl‐urea‐functionalized poly(propylene imine) dendrimer capable of binding 32 guest molecules and for a model host molecule that can bind only one guest molecule. The guest–host chemistry has been studied with 1H NMR spectroscopy, nuclear Overhauser enhancement spectroscopy NMR spectroscopy, T1‐relaxation NMR experiments, and IR spectroscopy. The 1:32 ratio with the dendrimer has been confirmed unambiguously from 1H NMR spectra of the complex after size exclusion chromatography. Competition experiments with guests bearing a carboxylic acid instead of a sulfonic acid in the binding motif have demonstrated that the sulfonic acid has superior binding strength. Also, the importance of a combination of noncovalent interactions has been shown via competition experiments with a guest lacking the uriedo moiety. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3792–3799, 2004
A survey of vapor cloud explosions: Second update
Authors: Lenoir Eric M. , Davenport John A.
Published: June 2004

Since publishing a listing of vapor cloud explosion incidents in 1977 and 1983, Industrial Risk Insurers has maintained an active database on these incidents. This second update gives the available data and reference sources on all known incidents.

Modeling of blast effects of vapor cloud explosions has evolved in recent years. The multi‐energy method is very promising but presently only models quiescent clouds. Losses show that quiescent dispersion of clouds is not always realistic. Explosively dispersed clouds or violent dispersion of clouds have occurred recently. Very powerful explosions have resulted.

As an insurance company trying to evaluate worst case scenarios, it is essential that research focuses on the modeling of explosively dispersed clouds or very turbulent clouds. The applicability of the multi‐energy method or the development of new methods for turbulent clouds should be investigated.
A simulation‐based decision support system for a pharmaceuticals manufacturing plant
Authors: Bernstein George , Carlson Eric C. , Felder Richard M. , Bokeny Roger E.
Published: June 2004

A drive to achieve manufacturing excellence is underway within the speciality chemicals industry. Components of this objective include improving capabilities for efficient technical and market information processes; responding quickly to changes in market demands and to the introduction of new product; reducing the time‐consuming and costly overhead associated with documentation, recordkeeping, and safety; and coordinating the activities of operating and management personnel, scientists and engineers, and management information specialists to create a fully integrated smoothly functioning organization [1].
A safety evaluation framework for process hazards management in chemical facilities with PES‐based controls
Authors: Drake Elisabeth M. , Thurston Clark W.
Published: June 2004

The chemical industry today is in transition, with increasing emphasis on total quality control along with needs to meet ever more stringent levels of health, safety, and environmental management. Fortunately, these needs are being met by tremendous strides in process monitoring and control instrumentation. Microprocessor‐based process sensors, programmable electronic systems (PESs), and precision throttling valves now improve the implementation and maintenance of complex process control strategies, with operators interacting with the process through modern human/machine interfaces. Sophisticated graphical displays and powerful control algorithms aid the operators in their work. Many formerly manual tasks are being automated. Some sources of human error are reduced by the use of PES controls, but these systems introduce new and different potential sources of error, leading to new implementation considerations.

Many of the hazard identification and risk assessment methodologies used today are based on techniques that assume independence of failures. However, possibilities for common mode failures and covert faults are greatly increased in process control systems that make use of PES technology. PES controls are interconnected through data highways; use common hardware and software functions in many modules; and may depend on central supervisory control computers for some critical control data. Today, achieving plant safety is a systems issue, requiring an integrated analysis with inputs from each of the disciplines involved in design and operation, as well as the guidance of safety and risk specialists. This article presents a systematic, semi‐quantitative approach to total system safety design in which modern programmable electronic monitoring and control systems are integrated with traditional administrative and engineering controls to achieve acceptable levels of operating risk. The philosophy presented is a reflection of the consensus of a group of experienced control system specialists from some ten leading companies.
Utilization and results of hazard and operability studies in a petroleum refinery
Authors: Pully Angela S.
Published: June 2004

The petroleum refining industry has been performing hazard analyses in process units to some extent since at least 1988 and in earnest since 1990, when the American Petroleum Institute published Recommended Practice No. 750, “Process Hazards Management.” The Hazard and Operability Study (HAZOPS) is the most widely used of the various analysis techniques available, in part because this highly structured technique is easy to teach and well‐suited for continuous process units.

The results of HAZOPS fall into two broad categories, tangible and intangible. The tangible results are obvious: worksheets which detail event scanarios for potential process deviations, and action items, or recommendations for changes to process equipment of procedures. In many cases, the action items address issues which have a purely economic impact or which are procedural in nature, involving little or no capital investment.

The intangible results or products of a HAZOPS include: the training and knowledge gained by the team participants, and better utilization of limited capital funds resulting from more detailed up‐front engineering when a HAZOPS is required prior to funding. An aggressive HAZOPS schedule also aids facilities in planning resources for process safety information updates where the necessary P&ID's or PFD's are out‐of‐date.

This paper details the experiences with HAZOPS at Chevron U.S.A. Products Company's Pascagoula, Mississippi Refinery. The manner in which HAZOPS are performed, the types of results obtained, and the benefits of the HAZOPS program will be discussed.
Energency response shortstop inhibition during the approach to an acrylic acid runaway polymerization
Authors: Levy Leon B. , Lakin Michael B.
Published: June 2004

The most common cause for runaway polymerizations of glacial acrylic acid (AA) is overheating of the material due to mechanical failure, human error, or nearby fire. Under such circumstances, dissolved oxygen (D.O) is consumed more rapidly than the AA stabilizer, p‐methoxyphenol (MEHQ), and “oxygen stravation” is the immediate cause of polymerization onset. From the known kinetics of oxygen disappearance, it is possible to calculate D.O. concentrations during a heatup period and to predict the time remaining until that concentration becomes unacceptably low. This information provides guidance for the timely activation of an emergency response shortstop inhibitor injection system so that there is enough time for adequate mixing of the inhibitor, phenothiazine (PTZ), to prevent or mitigate the polymerization.
Prediction of vessel and piping failure rates in chemical process plants using the Thomas model
Authors: Medhekar Subodh R. , Bley Dennis C. , Gekler Willard C.
Published: June 2004

Faced with the lack of historical data or access to specific plant maintenance records, the analyst can estimate failure rates for plant‐specific vessels and pipes using the Thomas model. The model uses available information regarding the vessel shape, size, and thickness along with the construction details of the vessel or pipe (number and type of welds, etc.). Maintenance and inspection history of the equipment can also be factored into the model, allowing the model to reflect the analyst's state of knowledge about the impact of these observed praictices on predicted failure rates. The model was orginally developed using a large database for predicting vessel and pipe failures for the nuclear industry but can be equally applicable to the chemical industry. Any additional information about plant‐specific failures can be easily factored into the analysis by using Bayesian techniques.

In the present application, the Thomas model was used to predict failure rates of process vessels storing corrosive and hazardous chemicals. Engineering judgement was used in making the model reflect the corrosive properties of the stored chemicals and the effectiveness of the inspection programs. Finally, the results of the model were compared with available industry wide data sources and were found to be reasonable.
Contractor hazard identification and control
Authors: Whitaker Gordon W.
Published: June 2004

There are unresolved problems with contractor injuries that operators must confront.
Physical modeling of water sprays—comparison against field operations
Authors: Ratcliff Michael A. , Petersen Ronald L. , Schatz Klaus W. , Heskestad Gunnar
Published: June 2004

This paper discusses the procedure developed for simulating water sprays at a reduced scale (i.e., physical modeling) and, more impotantly, compares the model spray characterstics to corresponding full scale spray characteristics. An ideal physically modeled spray would simulate actual spray momentum, water volume flow rate, air entrainment rate, discharge water pressure, spray angle, spray pattern and drop size distribution. Full scale measurements or estimates of air discharge velocity, momentum, entrainment rate and drop size distributions were obtained for two types of sprays at two discharge pressures, various spray angles and at a 500 gpm flow rate. Physical modeling was conducted to simulate the full scale nozzles at a 1:50 scale reduction using commercially available spray nozzles. Measurements of spray momentum, volume flow rate and air entrainment rate were obtined for a subset of spray angles used in the full scale testing. Particle size distribution was not measured since it was considered of secondary importance in the simulation. The results of the study showed that model and full scale momentum, volume flow rate and air entrainment rates compared well with corresponding full scale observations (i.e., within 10 percent for momentum, 20 percent for volume flow rate and 25 percent for air entrainment rate). The results indicate that the method used for simulating water sprays is valid and that the model sprays adequately simulate the mechanical action of full scale sprays on vapor clouds. The results provide evidence that physical modeling can be used to evaluate the effectiveness of water sprays as a mitigation technique.
Frequency estimates for transport‐related hydrofluoric and sulfuric acid release scenarios
Authors: Medhekar Subodh R. , Gekler Willard C. , Bley Dennis C.
Published: June 2004

An analysis was performed to predict the frequency of release associated with transportation scenarios for four refineries and a chemical plant in the South Coast Basin using hydrofluoric acid (HF) in the alkylation process/ chemical process. The analysis considers two settings. The first is the set of ongoing HF transportation scenarios, and the second is a projected set of HF and sulfuric acid transportation scenarios if the HF alkylation units of the refineries are replaced by sulfuric acid alkylation units.
Management of change—the systematic use of hazard evaluation procedures and audits
Authors: Sankaran N.
Published: June 2004

Process Safety Management is the application of management systems to the identification, understanding, and control of process hazards to prevent process related injuries and incidents. PSM activity has been thrust into the limelight with the promulgation of the OSHA rule, 29 CFR 1910.119, which went into effect on May 26, 1992. The practice of PSM is covered under several distinct elements, which are common to OSHA and other similar programs such as the API‐RP 750 (Management of Process Hazards). One of these important elements is the management of change. In its conventional sense, change can cover modifications to equipment and procedures. However, for purposes of this presentation I have defined change as modifications to an organization and work culture that may affect process safety.

In what follows I plan to illustrate how one company affected a change in safety culture and manages change to achieve its objectives in Process Safety Management excellence.
The corporation and the community: Credibility, legitimacy, and imposed risk
Authors: Rosenthal Isadore
Published: June 2004

Large segments of society no longer trust firms or government in regard to pronouncements on what is safe. Because of this distrust, particularly in regard to the chemical industry, the public has questioned many firms right to operate in their community and demanded and obtained increased rights for individuals to intervene directly in decisions by firms that might affect them.

Chemical firms must establish or restore their credibility and social legitimacy in order to maintain their social franchise to operate. At a minimum, this requires an understanding how the firm's stakeholders view the firm's imposition of risks on them and their families and the engagement of these stakeholders in discussions about the firm's products and operations and the risks attendant on its presence in the community. Some chemical firms have formed community advisory councils as a way of accomplishing this rapproachement. However, they have found that a community council may have its own agenda, forcing the firm to provide information and deal with issues it would have preferred to avoid.
Transient flow phenomena and reaction forces during blowdown of gas at high pressures through relief lines behind rupture discs
Authors: Perbal R.
Published: June 2004

In general, rupture discs are designed to give a virtually instantaneous pressure relief opening to a relief system at a predetermined pressure. For safe design of pressure relief systems, consideration must be given to the sizing and the specification of the rupture disc but also to the reaction forces that result when a gas is discharged. These reaction forces can be excessive in the case of venting at high pressures.

When a disc ruptures, a shock wave propagates through the gas in the piping behind the rupture disc. This exerts a transient reaction force on the pressure relief system. In the case of steady supersonic flow choking often occurs at one or more points in the pressure relief line and a shock is formed in the pipe. The pressure in the relief line may increase considerably during blowdown as a result of choking at the end of the pipe. Depress‐surization experiments were conducted with nitrogen at high pressures.

The results of the pressure measurements in the piping during blowdown are compared with exploratory calculations. The reaction forces exerted on a pressure relief system can be assessed from the pressures and the mass flow rate of the gas as a function of time. For safe design of pressure relief systems, both steady‐state flow reaction forces and the initial transient forces should be considered.
Managing the PHA team
Authors: Dowell A. M.
Published: June 2004

Lock 8 people in a room for 10 days with the charge to do a PHA (Process Hazard Analysis), to develop missing Process Safety Information, to make recommendations to reduce risk and to document all their work—What will result? Frustration and fatigue, or comradeship and accomplishment? The PHA effort must be managed to meet the objectives of the OSHA rule for Process Safety Management of Highly Hazardous Chemicals, and, equally important, to meet the needs of the individuals serving on the team. This paper presents learnings from over 14 years of leading and serving on HazOp teams. Here's how to get the best from the PHA experience.
Case histories of some power and control‐based process safety incidents
Authors: Griffin M. L. , Gurry F. H.
Published: June 2004

This paper presents some case histories of power‐and control‐based process safety incidents and near misses involving the Procter & Gamble Company and its affiliates.

A key part of our Process Safety Program is to learn from the incidents that we and others experience. Incidents in our facilities are investigated for basic cause, and the learnings are shared with other plants. In some cases it is necessary to change our design practices and standards. We believe that thorough incident investigation is a major tool in our continuous improvement efforts. Each of these events had the potential to cause serious personnel injury and/or major production losses. Fortunately, these incidents did not produce any reportable personnel injuries.

We are sharing these case histories of process safety incidents and near misses here so others can learn from them. The six incidents reviewed in this paper all resulted from the failure of a power or control system. We will review what happened, what we learned, and make recommendations to avoid future incidents like them. We hope that this will help avoid similar, possibly more serious, incidents in other facilities.
A comprehensive program for preventing cyclohexane oxidation process piping failures
Authors: Sadler Donald L. , Matusz Brian T.
Published: June 2004

In 1971, the Cyclohexane Oxidation Unit at the Monsanto Plant at Pensacola, Florida, suffered a pipe rupture that resulted in the formation of a cyclohexane vapor cloud of major proportions and disastrous potential. Catastrophe was averted because there was no ignition of the cloud.

The incident, plus past and present piping system remediation programs undertaken to prevent future occurrences as described in this article. The current program involves a comprehensive survey of critical piping systems utilizing flexibility analysis, acoustic emission testing, radiographic and ultrasonic inspection, HazOp safety studies, and distributed process controls to properly maintain and operate the critical piping systems.
Spill containment and destruction of a reactive, volatile chemical
Authors: Weirick M. L. , Farquhar S. M. , Chismar B. P.
Published: June 2004

A risk reduction project at a small Union Carbide Corporation facility included an unusual design feature that is the main subject of this paper. The project included a concrete secondary containment pit to contain and reactively destroy spilled material. The pit was designed so that the worst‐case spill scenario of flow conditions, ambient temperature, and wind stability would not result in emissions from the pit with fenceline concentrations that exceed regulatory limits. The containment pit is not the entire risk control system, but it is the final component of a multi‐layered risk mitigation system. To place the containment pit in context, the entire scope of the episodic risk control strategy is reviewed.
The real costs of risk analysis
Authors: Rosenthal Isadore , Lewis Philip G.
Published: June 2004

With the promulgation of the recent OSHA process safety management standard (PSM) and the proposed EPA rule on Risk Management Programs (RMP) for chemical accident prevention there is a shift in the incremental costs incurred by a firm from voluntary use of state‐of‐the‐art chemical process quantitative risk analysis (CPQRA).
Static electricity in pneumatic transport systems: Three case histories
Authors: Pratt Thomas H.
Published: June 2004

Three incidents, two explosions and one near miss, of electrostatic ignition of dust suspensions in pneumatic transport systems are reported. The incidents actually occurred in three separate systems; but, because of legal implications, they are reported in terms of one generic system. Incident A describes a near miss where there were some ungrounded ducts in the system. Incident B describes an explosion during the filling of an intermediate bulk container with a powdered material. Incident C describes an explosion in a bag filter (bag house) after some two years of operation. The discussions include some basic preventive measures which should be taken in similar systems to prevent the buildup of electrostatic potentials.
Low cooling tower level causes evacuation
Authors: Dowell A. M.
Published: June 2004

Is a utility part of the plant safety systems?

Is up‐to‐date documentation of the utility system needed?

Two operating units were evacuated during a small release of a toxic compound. The release occurred during a refrigeration system outage caused by low level in the cooling tower. Among the causes of the low cooling tower level was out of date documentation for the cooling tower makeup water supply.

This paper presents a multiple cause, system oriented incident investigation of the release. Additional causes and recommendations for improvement are included in the paper.
Flammability of metals and other elemental dust clouds
Authors: Cashdollar Kenneth L.
Published: June 2004

This paper reports results from a U.S. Bureau of Mines study of the flammability of various metals and other elemental dusts dispersed in air. The data are useful for evaluating the explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties—from the more volatile materials such as magnesium, sulfur, and zinc to the highly “refractory” materials such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in the Bureau of Mines 20‐L explosibility test chamber, using strong pyrotechnic ignitors. The parameters measured included the minimum explosible concentrations, maximum explosion pressures, and maximum rates of pressure rise. All of the elemental dusts ignited and burned as air‐dispersed dust clouds except the nickel, copper, molybdenum, and lead. In general, the dusts with the highest explosion pressures and rates of pressure rise were also those with the highest calculated, adiabatic flame temperatures and/or the ones that vaporized most easily, but this was not true in all cases. The effect of particle size on flammability was studied for the aluminum and iron dusts. The minimum explosible concentrations were relatively independent of particle size below 30 μm, but the highest explosion pressures and rates of pressure rise were found at the finest sizes tested.
Aspects of emergency relief design for reactive systems
Authors: Goetz David D. , Sawrey Jeffrey S.
Published: June 2004

An approach is presented to accurately design emergency relief systems for even the most complex chemical reactions. Two examples illustrate how large differences in relief requirements can result if small, but important, aspects of the calorimetry data are overlooked. Although both simple and rigorous kinetic models may seem to predict calorimetry data reasonably well, these examples demonstrate the importance of well‐designed experiments, optimization algorithms, rigorous kinetic modeling, correct physical properties, and dynamic simulations.

The first example shows how the inclusion of a subtle equilibrium reaction in the kinetic model will allow venting of an intermediate species, decreasing the reactant available for the highly exothermic irreversible reaction. The second example emphasizes the importance of a rigorous model for the decomposition of a large molecule where bond cleavage can occur between repetitive groups.

This example takes advantage of the tempering effect of intermediate decomposition products which are accounted forwith the rigorous model.
Dust and hybrid explosibility in a 1 m3 spherical chamber
Authors: Chatrathi Kris
Published: June 2004

The dust explosibility characteristics of Lycopodium, Cornstarch, Pittsburgh Bituminous Coal and Calcium Sterate were measured in a 1 m3 spherical explosion chamber at ambient pressures, ambient temperatures and at three different turbulence levels. Explosibility parameters measured were the maximum pressure, maximum pressure rate of rise and the initial pressure rate of rise. Propane explosibility and Hybrid explosibility (Cornstarch in the presence of propane) were also measured. For the hybrid system, the lower limits of explosibility and the effect of low propane concentrations on the explosibility of optimum Cornstarch concentrations were investigated. Finally, a relationship between maximum pressure rate of rise and initial pressure rate of rise was sought in order to lay a foundation for explosion suppression and explosion venting engineering methodologies.
Catastrophic failure of a liquid carbon dioxide storage vessel
Authors: Clayton W. Edward , Griffin Michael L.
Published: June 2004

This article describes the catastrophic failure of a liquid CO2 storage vessel and the chain of events that contributed to this incident. This incident happened in Procter & Gamble GmbH's citrus process in Worms, Germany. Three fatalities, over $20 million in property damage, and three month's lost production resulted.

Initially less than one‐fifth of the storage vessel was available for examination. The force of the explosion had propelled most of the vessel into the nearby Rhein River. The unavailability of the other parts of the vessel seriously hampered the incident investigation and prevented correct determination of the basic cause of the failure. Later recovery and inspection of additional parts of the tank allowed the investigation team to determine the correct basic cause.

The results of the inspections conducted on other liquid CO2 vessels are covered. These inspections resulted in most of these vessels being removed from service. Other actions taken to prevent similar incidents include:

Elimination of the use of carbon dioxide in many non‐critical applications.

Development and adoption of specific Company design requirements for liquid CO2 storage systems into standard Design Practices.
Studies about the influence of turbulence on the course of explosions
Authors: Scheuermann Klaus P.
Published: June 2004

Turbulence has a decisive influence on the course of dust and gas explosions. The aim of this study is to understand this influence in more detail and thereby to improve the assessment of explosions in technical systems.

Studies for maize‐starch/air mixtures (c = 750 g/m3) and for propane/air mixtures (λ = 1) are carried out in a 1 m3‐vessel. Ordinary in testing vessels the turbulence will be generated by a perforated dust dispersion tube. In order to generate a turbulence field as homogeneous as possible, a perforated plate is moved through the vessel. The turbulence decay is used to set the effective turbulence at the ignition point.

From the experimentally determined pressure/time courses, important quantities of turbulent combustion are calculated using a calculation model. The dependency of the turbulent flame speed sb on the turbulence intensity u′ is discussed for the closed and the vented vessel.
A methodology for assessing catastropic damage to the population and environment: A quantitative multi‐attribute approach for risk analysis based on fuzzy set theory
Authors: Christen P. , Bohnenblust H. , Seitz S.
Published: June 2004

A worldwide discussion about catastrophic events in the chemical process industry was initiated by major disasters such as Seveso, Flixborough and Bhopal. As a result of the disaster in Basel (Switzerland), known as “Schweizerhalle,” special regulations regarding catastrophic events were set up in Switzerland. In this context a method for the quantitative evaluation of the risks associated with stationary chemical installations was developed. In the past, only one attribute for assessing the magnitude of impact, namely the number of fatalities, was considered risk analyses. In this paper a methodology for an extended damage assessment of the overall impact of an event including damage to man and animals, to ecosystems and natural resources, and to property is presented. The crucial question is how the overall impact can be represented by a limited number of indicators. Two basic questions are also important in this context: First, how can we assess and quantify the inherent fuzziness of the notion “catastrophe?” Second, how can we describe the impact by using different indicators in a multi‐dimensional way? The main aspects of this method, namely the indicator appraisal and the linking of the indicator values to a single disaster value are discussed in this paper.
An advanced method for the estimation of reaction kinetics, scaleup, and pressure relief design
Authors: Melhem G. A. , Fisher H. G. , Shaw D. A.
Published: June 2004

This paper presents an advanced modeling approach which significantly improves predictions of reaction rates and critical data that engineers need to design effective pressure relief systems. Ideally, pressure relief systems are sized exactly for the reaction characteristics of the chemicals in the vessel. However, with many chemicals and chemical mixtures, reaction chemistry is difficult to characterize because the individual components interact in complex ways. Furthermore, the high cost and risk of full‐scale reactivity experiments make test data scarce. Chemical engineers bridge this gap in part with small‐scale tests and modeling computer codes such as the one developed by the Design Institute for Emergency Relief Systems (DIERS). The comprehensive approach developed in this paper provides a reliable design basis for difficult systems, including highly energetic and nonideal reactions, systems with continuing reactions in piping and containment vessels, and systems where homogeneous bubble collapse caused by rapid depressurization could cause a catastrophic vessel failure. We first examine possible mechanisms for catastrophic vessel failure and associated consequences. Next, we outline a detailed approach for emergency relief system design and reactivity testing.
A method for implementing a piping inspection program
Authors: Matthews Peter B. , Beberman Julie A.
Published: June 2004

Recent catastrophic piping failures dramatically demonstrate the importance of implementing a piping program. Piping system leaks and ruptures have caused death and injury to plant workers, firefighters, and the public. Significant financial consequences due to unexpected downtime and property damage have plagued industry. The environment has also suffered from the release of toxic chemicals. In the chemical industry, roughly 30% of the catastrophic losses have been historically attributable to piping failures.
Critical temperatures for the thermal explosion of liquid organic peroxides
Authors: Kotoyori Takashi
Published: June 2004

A procedure is presented herein to calculate the critical temperature for the thermal explosion (hereafter symbolized as Tc) of an arbitrary quantity of thermally unstable liquid placed in an arbitrary container, by measuring experimentally the rate of heat transfer from the container as well as the rate of heat generation of the liquid sample in temperature increments of 1.25 K. The Tc values of ten liquid organic peroxides are then calculated in accordance with the above procedure for the practical situation arising when the liquids are either in a Dewar flask which is used in the BAM (Bundesanstalt für Materialforschung und ‐prüfung, Berlin) heat‐accumulation storage test or in a 5‐ or a 10‐L polyethylene container which are used by the peroxide manufacturing company for carrying 5‐ or 10‐kg quantities of liquid organic peroxides to the users. For the Dewar flask, the corresponding measured values were available, and they showed good agreement with the calculated ones. The new findings introduced in this article are that there is a prospect that one can predict the result of a BAM test by calculation for a solid as well as for a liquid; in addition, for liquids, there is also a possibility that one can calculate the Tc value of an arbitrary quantity of liquid placed in an arbitrary container.
Advantages of the new version VDI 3673. Part 1 in comparison with the chapter 7 of NFPA 68
Authors: Bruderer Reinhard E.
Published: June 2004

VDI (Society of German Engineers) submitted a new version for pressure release of dust explosions in November 1992 which will replace the June 1979 edition. Equations are now favored and nomograph take second place. NFPA 68, 1988 edition, which was reissued in 1994 and is presently being revised already contained some newer data but used the same range of application as the 1979 VDI. Such range of application was now expanded from 1 m3 down to 0.1 m3 and from 1,000 m3 to 10,000 m3. Static activation pressure was previously limited to 0.5 bar. Now 0.1 bar to 1 bar gage can be used. Dusts with a deflagration index of 800 bar·m/s can be dealt with. Previously the limit was set at 600 bar·m/s. It is the intent of this paper to show possible savings. Pressure and flame behavior outside vented vessels will be addressed as well as the special case for pneumatic conveying.
Conflicts and decisions in the search for inherently safer process options
Authors: Hendershot Dennis C.
Published: June 2004

Identification of inherently safer process options is a multi‐dimensional problem. Nearly all chemical processes involve a number of processing steps. Associated with each processing step there is usually a number of hazards or hazard types, for example, high pressure, high temperature, acute toxicity, chronic toxicity, fire, explosion. A process which is inherently safer with respect to one of these hazards may be more hazardous with respect to another hazard. Several examples will be discussed, including selection of refrigerants, batch vs. continuous reaction, and solvent selection for a batch exothermic reaction. These examples illustrate the importance of a thorough understanding of all of the potential hazards in the process. Finally, some tools for evaluating process options and selecting among a group of processes with conflicting inherent safety characteristics are discussed.
The DIERS users group: Status and current activities
Authors: Fisher Harold G.
Published: June 2004

One hundred nine companies have formed the DIERS Users Group, a Design Institute of the AIChE, to cooperatively assimilate, implement, maintain and upgrade the DIERS methodology. The purpose of the group is to

reduce the frequency, severity and consequences of pressure producing accidents

and

develop new techniques which will improve the design of emergency relief systems.

Membership in the DIERS Users Group offers access to refinements of the DIERS technology, participation in development of additional technology, and an opportunity to share learning experiences. Membership is open to industrial or engineering organizations interested in the design, use or manufacture of emergency relief devices and systems. Semiannual three‐day technical meetings are held at various locations and feature technology presentations by member company representatives and invited speakers and discussion of the results of computational example problems and experimental round robins. There are no fees for participation.
Expressions for gravity drainage of annular and toroidal containers
Authors: Hart Peter W. , Sommerfeld Jude T.
Published: June 2004

The time required to drain process or storage vessels of their liquid contents can be of crucial importance in many emergency situations. Over the years, many formulas have been developed to compute the time requirements for draining vessels of various geometric configurations. These formulas typically assume gravity drainage through an orifice type of opening at the bottom of the vessel. In this article, analytical expressions are developed to compute the times required for complete drainage of annuli (both horizontal and vertical), as well as horizontal tori, solely under the influence of gravity. Annuli often form the shell side of double‐pipe heat exchange devices, while horizontal tori are often employed as distributing rings or manifolds in various mass transfer operations. Large vertical tori are sometimes used as promotional devices for advertising purposes (e.g., huge tires), but are not commonly used to contain fluids (presumably because of structural and other considerations). The drainage time expression for horizontal annuli incorporates elliptic integrals.
Thermal ignition kinetics of wood sawdust measured by a newly devised experimental technique
Authors: Chong Li V. , Shaw Ian R. , Chen X. Dong
Published: June 2004

The activation energies of two wood sawdusts were determined using an experimental technique based on the crossing‐point temperature concept, which was derived from the transient model of self‐heating in a solid. The two samples used in this study were treated and untreated sawdust. The activation energies measured were 106 ± 4 kJ mol−1 for the treated sawdust and 90 ± 3 kJ mol−1 for the untreated sawdust. These values are similar to those in previously published results which were obtained using the steady‐state model. The transient model provides a quicker yet sufficiently accurate method of determining thermal ignition kinetics.
Testing trnsformer oil
Authors: Turcotte Robert R.
Published: June 2004

Suddenly, the unexpected happens—the power goes out—a critical transformer has failed. And just as suddenly, your plant is out of business. Since there are no visible moving parts there is a tendency to think that nothing can go wrong. But, preventive maintenance testing of transformers is not difficult to justify when you consider the high cost of repairs and the impact of an unscheduled outage of plant operation.
CCPS initiative to assist small and medium enterprises in improving their safety performance
Authors: Witter Ray E.
Published: June 2004

The Center for Chemical Process Safety (CCPS) has been concerned with the difficulty that Small and Medium Enterprises (SME's) face in improving their safety performance and in coping with EPA and OSHA regulations. Over the past several years, efforts to reach out to SME's by technical societies, trade associations, and other groups have not been fully effective, and for the most part have not reached SME's. To meet this challenge, CCPS has formed a committee to explore methods of effectively reaching SME's and to develop programs to meet their needs.
Inherent safety, health, and environmental (SHE) reviews
Authors: French Raymond W. , Williams Donald D. , Wixom Everett D.
Published: June 2004

Implementing an Inherent SHE Review process is under way at the Exxon Chemical Company and progress is being made in the pursuit of inherently safer, healtheir, and environmentally friendly processes. The review integrates well with the company's systems for process safety management, new product development, and project execution. In addition, the Inherent SHE Review process has been quite helpful in educating the organization with regard to the appoprite use of the laboratory in developing reactive chemistry understanding during product and process development. Another benefit of the Inherent SHE Review process is the proactive involvement of industrial hygiene early in the product development and project execution processes.
Applying inherently safer concepts to a phosgene plant acquisition
Authors: Gowland Richard
Published: June 2004

During the 1980's Dow Chemical acquired a urethanes business in Europe consisting of two major installations. These plants were of immediate concern due to large‐scale production and use of phosgene at one of the sites. Even though Dow has considerable experience in the bandling of chlorine, they had limited experience with phosgene in Europe. After the impact of the acquistion was assessed, a high‐level transition team was appointed by the Vice President of Manufacturing in Europe to evaluate and manage risk factors in the accquired units. Safety in manufacturing was the first item on their agenda.

In many cases the activities of the transition team were driven by the principles of Inherently Safer Process Design (Substitute, Minimize or Intensify, Moderate or Attenuate and finally Simplify). The net effect of the work done since acquisition is that risk exposure to the public in the adjacent village has been considerably reduced. In addition, fugitive emissions of toxic materials have been eliminated. Economic evaluation since the projects were enacted has demonstrated that many of the activities could have been justified purely on the basis of return on investment.
Applying risk assessment principles to a batch distillation column
Authors: Woodward John L. , Moosemiller Michael D. , Chopp Robert
Published: June 2004

Some distillation columns in the chemical industry are operated in batch mode with a fairly short operating cycle. At the end of each cycle the columns are cooled and recharged. During the cooling cycle, air will be drawn into the column by the action of a vacuum relief valve. Consequently, for a finite portion of the operating cycle a flammable mixture will exist in the column.

Here we evaluate the risk posed by such an operation to see if a mitigation measure is justified. We develop a fault tree and estimate the frequency of ignition by all possible ignition sources. By comparing the risk reduction attainable by installing a lightning protection system with that attainable by using an inert blanketing system the lightning protection system is found to be the preferred solution. It provides about the same risk reduction at a lower overall cost.
Pressure relief consideration for refrigeration equipment
Authors: Leung Joseph C.
Published: June 2004

Pressure relief sizing for refrigeration equipment is considered in this paper. In particular the ASHRAE fire sizing formula [2] is critically examined and comparisons are made with methods employed in other engineering institutes. The traditional sizing approach based on vapor relief is re‐exmained in light of the recent findings from the DIERS (Design Institute for Emergency Relief Systems) work [11]. The occurrence of two‐phase discharges during relief may result in significant overpresurization of the refrigeration equipment. The purpose of this paper is to suggest a methodology adequate for most designs and which has been verified with available experimental data.
Catastrophic failure of an ammonia/air mixer
Authors: Verduijn W. D.
Published: June 2004

Kemira B.V. operates a 1200 metric tpd (100%) high pressure nitric acid plant in Rozenburg, the Netherlands since 1968. Until the incident described here occurred, operation had always been uneventful. In August 1993, however, the ammonia/air mixer suddenly burst open, releasing large amounts of air and ammonia to atmosphere. Two persons working in the plant miraculously missed being hit by the gas jet and flying debris. This paper describes the incident, its cause and measures taken to prevent reoccurrence.
Development and communication of worst‐case scenarios for the EPA risk management program
Authors: McCready David
Published: June 2004

This AIChE/CCPS sponsored workshop brought together a panel of experts to discuss the development and communication of worst‐case scenarios for EPA's proposed Risk Management Program (RMP) Regulation. This paper presents specific issues raised during the Workshop, such as selecting release scenarios, performing hazard assessments, and communicating the results. However, the ultimate goal is chemical accident prevention and preparedness. Findings are not attributed to the individual experts but represent the view of the discussion chairman.
EPA's risk management regulation: Communicating worst‐case scenarios
Authors: Auger John E.
Published: June 2004

I would like to begin with a little exercise—I would like you to transport yourself back to your plant. Now, as you're back in your office, imagine for a moment that the plant emergency alarms start to go off. You catch a faint hint of ammonia as you walk to your office window. What you see can easily be described as your worst nightmare. You feel as though your heart has stopped and you freeze as if you were paralyzed. The 40 million pound (18 million kilogram) capacity double‐walled ammonia storage tank located about 200 yards (182 meters) from your office has a massive leak. Ammonia is vaporizing and being carried downwind toward the city in which you and your family live.

All right—enough of the nightmare. What went through your mind? How would you react? What would be the impact on you, your family, your community? It wouldn't be good, I can assure you.

Why have I tried to ruin your day by asking you to live a nightmare? For one simple reason—to show you what the Environmental Protection Agency (EPA) is going to make us all do under its proposed Risk Management Program (RMP) regulation. In fact, the EPA goes a step further. It will ask us not only to create our nightmares for ourselves, but to share them with the communities around our plants that could be impacted by our nightmare releases.
Human factors: Case histories of improperly managed changes in chemical plants
Authors: Sanders Roy E.
Published: June 2004

Chemical plant employees enjoy a safer place to work than most other places of employment. Despite the excellent overall record, there have been some tragic, catastrophic chemical plant accidents that have tarnished an excellent performance.

Some of these tragedies were the result of inadvertent, unintended or poorly performed changes. This paper will attempt to convince the audience there have been too many incidents that have occurred because there were failures in managing changes in chemical plants.

Medicre “Management of Change” systems can be strengthened and effective “Management of Change” systems can be made more effective through sharing simply written reports. Concise, well written case histories of past mistakes with sketches and a generous number of photos should be shared with chemical plant personnel who are responsible for day to day operations to change some plants' culture.