bluuebunny/crossref_metadata_2025 huggingface dataset:
Ammonia exchange on clinoptilolite from mineral deposits located in Mexico
Authors: Leyva‐Ramos Roberto , Aguilar‐Armenta Gelacio , Gonzalez‐Gutierrez Linda V , Guerrero‐Coronado Rosa M , Mendoza‐Barron Jovita
Published: April 2004

This work investigated the ion exchange of ammonia on clinoptilolite obtained from mineral deposits located in San Luis Potosi and Sonora, Mexico. Experimental ion exchange isotherm data were obtained in a batch adsorber. The effects of temperature and solution pH on the ion exchange capacity were studied and it was found that the exchange capacity was slightly increased by augmenting the temperature and by decreasing the pH from 6 to 3. The ion exchange capacity was independent of the diameter of the zeolite particles. The reversibility of ion exchange was analyzed by desorbing the ammonia exchanged on the zeolite. The ion exchange was reversible when 1% NaCl solution was used as the desorbing solution, but more ammonia was desorbed using 1% KCl solution in the desorption step. It was concluded that a considerable amount of ammonia was exchanged on the clinoptilolite and that the exchange capacity was slightly dependent on the temperature and pH. Copyright © 2004 Society of Chemical Industry
CAP reform, competitiveness and sustainability
Authors: Rickard Séan
Published: April 2004

Franz Fischler has recently published his proposals for (further) reform of the Common Agricultural Policy (CAP). In summary they amount to an attempt to achieve an agricultural industry that is not only more competitive and profitable but also ecologically and environmentally sustainable. For Franz Fischler, sustainability is defined as more than the effective conservation and regeneration of natural resources; it also involves sustaining the presumed contribution of farming to rural development. This latter objective is the focus of the newly introduced second pillar of the CAP and can be interpreted as an attempt to arrest the steady decline in the number of smaller‐sized farm businesses. Franz Fischler has pointed to the widespread support for these three objectives across EU populations and, subject to WTO constraints on trade distorting policies, the right of every society to choose its own agricultural policy. However, the analysis of the reform's objectives contained in this paper is that they form an irreconcilable trinity and ultimately policy makers will have to choose between a competitive industry and the protection of smaller farm businesses. This paper argues that in reality there is no choice. Globalisation will both drive and demand a more productive and competitive food chain in order to meet the demands of rising affluence and a burgeoning world population. It also argues that the industrialisation of farming is not automatically in conflict with the conservation and regeneration of natural resources. Copyright © 2004 Society of Chemical Industry
Pressure‐Induced cis‐to‐trans Isomerization of Poly[(p‐methylthiophenyl)acetylene] Prepared with a [Rh(norbornadiene)Cl]2 Catalyst – A Raman, UV‐Vis, and ESR Study
Authors: Huang Kai , Mawatari Yasuteru , Tabata Masayoshi , Sone Takeyuki , Miyasaka Atsushi , Sadahiro Yoshikazu
Published: April 2004

Summary: A stereospecific polymerization of a novel aromatic acetylene containing an alkyl sulfide group, i.e., (p‐methylthiophenyl)acetylene (pMeSPA) was successfully performed to selectively give the corresponding polymer bearing a cis‐transoid structure as a main geometrical form and a very high molecular weight, $\overline M _{\rm n}$ = 1.7–5.8 × 106 in high yields. This was accomplished when a Rh complex catalyst, [Rh(norbornadiene)Cl]2, was used in the presence of triethylamine (TEA) solvent as a cocatalyst and its mixed solvents with TEA, together with a detailed characterization of the resulting polymers before and after compression at room temperature. Based on the data obtained before and after compression, it was concluded that compression of the PpMeSPA polymers induced a cis‐to‐trans isomerization at room temperature under vacuum even in the solid state (the Figure shows the radical generated by compression).

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Anionic Copolymerization of 5‐(N,N‐Dialkylamino)isoprenes
Authors: Mannebach Gerd , Müller Axel H. E.
Published: April 2004

Summary: The anionic copolymerization of various 5‐(N,N‐dialkylamino)isoprenes initiated by sec‐butyllithium in hexane is investigated. The bulkiness of the alkyl side chains has a strong influence on the copolymerization behavior, monomer reactivity decreasing in the order of alkyl groups methyl > ethyl ≈ propyl > isopropyl. Polymer structures vary from nearly block over tapered and gradient to random, depending on the relative reactivities of comonomers. Since the basicity of the tertiary amino groups depends on the nature of the alkyl groups, it is possible to vary the basicity along the polymer backbone by a suitable choice of the comonomers. Copolymerization kinetics do not seem to follow first‐ or second‐order with respect to monomer conversion and they cannot be described using the terminal model.

General structure of obtained polymers.

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General structure of obtained polymers.
Internet tools for supporting of lay stakeholders in the framework of the democratic paradigm of environmental decision making
Authors: Lotov Alexander V.
Published: April 2004

The paper describes the concept of Internet tools that may help implementing a democratic paradigm of environmental decision making, which is based on the desire to involve lay stakeholders into the process of decision making. It is clear that lay stakeholders usually have minimal knowledge on the ways how to solve environmental problems. The gap among knowledge and actions of lay stakeholders may be extremely dangerous. In this paper we propose visualization‐based Internet tools that can help lay stakeholders to study the environmental problems and base their actions on a better understanding of the issues. The tools are based on multi‐criteria exploration of the whole variety of possible environmental decision alternatives that helps to understand the feasibility frontiers and individual selecting several preferred feasible decision alternatives. We argue that such Internet tools can be mastered by computer‐literate lay stakeholders and used by them in the process of preparation to political actions related to the final choice. Copyright © 2004 John Wiley & Sons, Ltd.
Nitric oxide modulates local reflexes of the tailfan of the crayfish
Authors: Araki Makoto , Schuppe Hansjürgen , Fujimoto Sawako , Nagayama Toshiki , Newland Philip L.
Published: April 2004

Electrical stimulation of sensory neurons that innervate receptors on the tailfan of crayfish evokes a reflex response of motor neurons that produce movements of the blades of the tailfan, the uropods. We analyzed the modulatory effects of nitric oxide (NO) on the spike frequency of the reflex response. Bath application of L‐arginine and SNAP, which elevate endogenous and exogenous NO levels, increased the frequency of the evoked response, whereas the application of L‐NAME and PTIO, which reduce NO levels, decreased the frequency of the response. To determine through what pathway and target NO exerted these effects we bath applied ODQ, an inhibitor of soluble guanylyl cyclase (sGC), which decreased the frequency of response, and 8‐br‐cGMP, which increased the spike frequency of response. To provide further evidence that NO acts via sGC, we elevated NO levels with L‐arginine while simultaneously inhibiting sGC with ODQ. This application reduced the response to control levels, indicating that NO in the terminal ganglion of crayfish acts via sGC to modulate cGMP levels, which in turn regulate the responses of the uropod motor neurons. © 2004 Wiley Periodicals, Inc. J Neurobiol 30: 176–186, 2004
Co‐expression of neuregulins 1, 2, 3 and 4 in human breast cancer
Authors: Dunn Mariana , Sinha Prakash , Campbell Rebecca , Blackburn Edith , Levinson Neil , Rampaul Raj , Bates Tom , Humphreys Stephen , Gullick William J
Published: April 2004

We have produced antibodies to the NRG2‐alpha, NRG2‐beta, NRG3 and NRG4 proteins and used these, and previously described antibodies to NRG1‐alpha and NRG1‐beta, to detect expression of each ligand by immunocytochemical staining in a series of 45 breast cancers. Each protein was expressed in a proportion of cases. Statistical analysis suggested that expression of one factor was associated with a high probability that other members of the family were co‐expressed. NRG2‐alpha expression was associated with node positivity (p‐value = 0.005). The mRNAs for NRG1, 2, 3 and 4 were found in established breast cancer cell lines and NRG1, 2 and 3 mRNAs were detected in primary breast cancers. Expression of NRG4 mRNA was shown by in situ hybridization in sections from primary breast cancers. This data demonstrates that each member of the NRG family of ligands is expressed in breast cancer and suggests that they may be involved in regulating cell behaviour. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Molecular modeling of protein function regions
Authors: DeWeese‐Scott Carol , Moult John
Published: April 2004

Experimental protein structures often provide extensive insight into the mode and specificity of small molecule binding, and this information is useful for understanding protein function and for the design of drugs. We have performed an analysis of the reliability with which ligand‐binding information can be deduced from computer model structures, as opposed to experimentally derived ones. Models produced as part of the CASP experiments are used. The accuracy of contacts between protein model atoms and experimentally determined ligand atom positions is the main criterion. Only comparative models are included (i.e., models based on a sequence relationship between the protein of interest and a known structure). We find that, as expected, contact errors increase with decreasing sequence identity used as a basis for modeling. Analysis of the causes of errors shows that sequence alignment errors between model and experimental template have the most deleterious effect. In general, good, but not perfect, insight into ligand binding can be obtained from models based on a sequence relationship, providing there are no alignment errors in the model. The results support a structural genomics strategy based on experimental sampling of structure space so that all protein domains can be modeled on the basis of 30% or higher sequence identity. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Structural features of the inactive and active states of the melanin‐concentrating hormone receptors: Insights from molecular simulations
Authors: Vitale Rosa Maria , Pedone Carlo , De Benedetti Pier G. , Fanelli Francesca
Published: April 2004

Comparative molecular dynamics simulations of both subtypes 1 and 2 of the melanin‐concentrating hormone receptor (MCHR1 and MCHR2, respectively) in their free and hormone‐bound forms have been carried out. The hormone has been used in its full‐length and truncated forms, as well as in 16 mutated forms. Moreover, MCHR1 has been simulated in complex with T‐226296, a novel orally active and selective antagonist. The comparative analysis of an extended number of receptor configurations suggests that the differences between inactive (i.e., free and antagonist‐bound) and active (i.e., agonist‐bound) states of MCHRs involve the receptor portions close to the E/DRY and NPxxY motifs, with prominence to the cytosolic extensions of helices 2, 3, 6, and 7. In fact, the active forms of these receptors share the release of selected intramolecular interactions found in the inactive forms, such as that between R3.50 of the E/DRY motif and D2.40, and that between Y7.53 of the NPxxY motif and F7.60. Another feature of the active forms of both MCHRs is the approach of “helix 8” to the cytosolic extension of helix 3. These features of the active forms are concurrent with the opening of a cleft at the cytosolic end of the helix bundle. For both MCHRs, the agonist‐induced chemical information transfer from the extracellular to the cytosolic domains is mediated by a cluster of aromatic amino acids in helix 6, following the ligand interaction with selected amino acids in the extracellular half of the receptor. Proteins 2004. © 2004 Wiley‐Liss, Inc.
PROFAT: A user friendly system for probabilistic fault tree analysis
Authors: Khan Faisal I. , Abbasi S. A.
Published: April 2004

A methodology has been developed to conduct probabilistic fault tree analysis during risk assessment in chemical process industries. The methodology is based on a system involving (a) development of fault tree, (b) determination of minimum cutsets or shortest pathways leading from initiating events (malfunctioning) to the top event (the major accident), (c) probability analysis, and (d) working out improvement index values. To this end techniques of Boolean algebra, structure moduling, analytical method of cutsets finding (top‐to‐bottom algorithm), Monte‐Carlo simulation, optimization technique and fuzzy probability set have been used.

We named the methodology Analytical ‐Simulation Methodology (ASM) and we developed a software package PROFAT (PRObabilistic fault tree analysis) to facilitate the use of the methodology in a rapid and eflective, yet user‐friendly manner. PROFAT enables the user to find out, in an industry, (i) initiating events which may eventually lead to a major accideizt, (ii) shortest routes (minimum cutsets) a series of initiating events may take place while aiding each other in causing the accideizt. (iii) the probabilities of occurrence of such initintirig events, (iv) relative contributiom of each of the initiating events and, finally, (v) identfiing initiating events with the greatest potential to cause the top event (major accident) so that accident prevention strategies aud emergency preparedness plans can be focused on them.

The noteworthy attributes of the system are: resilience towards lack of precision in the basic data, swift processing with moderate requirements of computation cupacity (sophistication of computers needed), ease of use, and direct1y utiliz‐able output. The applicability of PROFAT has been denionstrated with a case study of a sulfolane manufacturing unit.
Safety performance in ammonia plants: Survey VI
Authors: Williams Gerald P.
Published: April 2004

The worldwide safety performance is shown of 89 ammonia plants operating in 25 countries around the world. A three‐year period from 1994–1996 is covered, and safety incidences including fires and explosions are reviewed. This recent safety performance is compared with the performance history from past surveys. A list of noteworthy safety practices recommended by the plants is also presented.
The world's worst industrial accident of the 1990s what happened and what might have been: A quantitative study
Authors: Khan Faisal I. , Abbasi S. A.
Published: April 2004

The world's most destructive industrial accident of the current decade, in terms of human lives lost (over 60) and damage to property (over $15 million), occurred at the petroleum refinery of Hindustan Petroleum Corporation Limited (HPCL) at Vishakhapatnam, India, on September 14, 1997. In this paper we have used two computer automated tools recently developed by us, MAXCRED [7], and DOMIFFECT [8], to determine their ability to forecast the details of the incident. When the situation at Vishakhapatnam, prior to the accident, was studied with MAXCRED for potential accidents and their likely consequences, the tool was able to generate a scenario which forecast the incident quite closey. We then used MAXCRED and DOMIFFECT to tell us what else might have occurred.

The prognosis is quite scary. The computer tools reveal a few lucky breaks: had the situation and the events conspired a little more treacherously, the HPCL disaster would have been much larger in magnitude. Indeed the incident could have resulted in a death toll of the magnitude of the Bhopal Gas Tragedy with additional massive damage to propert.

This paper show‐cases the usefulness of MAXCRED and DOMIFFECT and also brings forth lessons which all industries would benefit from learning.
Oychem Y2K contingency planning
Authors: Scheier Ephraim
Published: April 2004

The Year 2OOO problem has been widely publicized. Significant efforts are underway to identify and remedy problems with equipment that may malfunction. Recognizing that despite these efforts there may still be Y2K failures, attention need to be focused on potential process equipment malfunctiom and contingency planning for Ear 2000 related incident.

Y2K incidents may arise from problems within the plant or from external sources. Ongoing efforts to prioritize and remedy Y2K systems and equipment have reduced the probability and impact of problems. Contingency planning addresses the residual Y2K risk.

This paper describes an OxyChem approach to managing the potential Y2K problems and steps being taken to develop contingency plans. The paper includes examples of Y2K related failures and emphasizes contingency planning, procedures and preparedness.
Inspection, testing and maintenance of fire protection systems at industrial plants
Authors: Dieken Dominique
Published: April 2004

Every year, fire supprersion system fail to operate satisfactorily in fire situations. In about one‐third of these cases, the cause is inadequate inspection, testing and maintenance. An Edison Electrical Institute (EEI) study found that 49 percent of gaseous suppression systems in combustion turbine units failed to operate satisfactorily in a 2O‐year period, with a total property damage of $15.9 million. An example of a fire with a tragic consequence involved lube oil at a cogeneration plant on Christmas Day in 1992, which resulted in the death af three plant operators. Automatic sprinkler protection was provided for most of the plant, including lube oil hazard, but the systems had been turned off. Had the system been operational, the fire may have been controlled.
SACHE case histories and training modules
Authors: Willey Ronald J.
Published: April 2004

Training can be simplified. Vivid slides of case histories of accidents, supplemented with easy‐to‐use lecture notes for the universities and industry, are now available through AIChE's Center for Chemical Process Safety (CCPS). Since 1991, a committee composed of approximately seven academics, seven industrial representatives, and three government representatives have worked together to produce teaching modules for use in the undergraduate educational experiences at colleges and universities. This committee, called the Undergraduate Education Committee (UEC), was established by CCPS to enhance chemical engineering undergraduate education in the area of chemical rocess safely. To date, the committee has produced 6 problem sets, and 15 case histories/training modules that consist of slides and lecture notes. These products are made available to universities who join a group called SACHE (Safity and Chemical Engineering Education) and can be used by instructors in classroom and seminar formats. The focus for this paper is a summary of case histories available (Tank Failures, Nitroaniline Reactor Rupture, Seveso, Bhopal, and Pasadena). Industry can also benefit by usin these informative modules in training their tecffnical employees.
Electrostatic ignitions in everyday chemical operations: Three case histories
Authors: Pratt Thomas H. , Atherton John G.
Published: April 2004

In operations where there are flammable or combustible materials it is axiomatic that all conductive equipment be firmly bonded and grounded. Even though vigilance to such matters may be exercised in a given operation there may be times where detail are overlooked or deemed to be of no consequence; and, in some cases, these detail can have dire conesquences. This paper sets forth three such case histories where proper grounding was not done and an electrostatic ignition resulted.

The first example is the drawin of a sample of toluene into a metal pail ‐ a common, everyday operation which had been done many times before. The second example is pumping toluene into a reactor through a chemical hose where the stiffening wires were not bonded to the couplings, an “everyday” operation. The third examle is the offloading of an aluminum powder from a bulk truck ‐ a one‐time, makeshift operation. These examples are discussed to give operators an appreciation for the vigilance required to keep all conductive objects grounded in chemical operations where flammabel or combustible material are present.
A new approach to explosion suppression
Authors: Theré Frank , Harmanny A. , Van Gelder P.
Published: April 2004

One of the most widely applied protective systems, to reduce the effects of an explosion, is explosion pressure release (venting). There is a disadvantage to venting in that, with an explosion, there is considerable (fire) damage which can result in major repair costs and production losses. In addition there is a growing resistance against the venting of large flame jets and combustion products, because of environmental and safety issues.

A good alternative to explosion venting is explosion suppression. If designed, installed and maintained properly, explosion venting is a reliable protective technique. The main obstacle to the widespread acceptance of suppression technology, apart from the initial investments, is the intensive maintenance, which can have considerable impact both on production costs and efficiency.
A “worst case” methodology for risk assessment of major accident installations
Authors: Hirst I. L. , Carter D. A.
Published: April 2004

This paper considers the application of one of the weighted risk indicators used by the Major Hazards Assessment Unit (MHAU) of the United Kingdom's Health & Safety Executive (HSE) in formulating advice to local planning authorities on the siting of new major accident hazard installations. In such cases the initial consideration is to be assured that the proposed installation would not be incompatible with existing land uses in the vicinity, as determined by the categorization of the existing populations and the estimated levels of individual risk which the proposed installation would impose upon them.

An analysis of the consequences and likelihood of a single “worst case” event, coupled with MHAU's “Risk Integral,” is then undertaken. This enables the societal risk aspects of the proposal to be considered at an early stage and, in many cases, allows a prompt response. The paper describes the methodology and includes several case studies based on MHAU's day to day work which illustrate its use.
The development of acute exposure guideline levels for hazardous substances
Authors: Rusch George M. , Garrett Roger , Tobin Paul , Falke Ernest , Lu Po‐Yung
Published: April 2004

The primary purpose of the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances (NAC/AEGL) is to develop guideline levels for short‐term exposures to airborne concentrations for approximately 400 to 500 high priority, acutely hazardous substances within the next ten years. These Acute Exposure Guideline Levels (AEGLs) are needed for a wide range of planning, response, and prevention applications.

The NAC/AEGL Committee seeks to develop the most scientifically credible, acute (short‐term) exposure guideline levels possible within the constraints of data availability, resources and time. This includes a comprehensive effort in data gathering, data evaluation and data summarization; fostering the participation of a large cross‐section of the relevant scientific community; and the adoption of procedures and methods that facilitate consensus‐building for AEGL values within the Committee. The NAC/AEGL Committee is currently comprised of representatives of federal, state and local agencies, private industry and other organizations in the private sector that will derive programmatic or operational benefits from the existence of the AEGL values.

AEGL values are determined for three different health effect end‐points. These values are intended for the general public where they are applicable to emergency (accidental) situations. Threshold exposure values are developed for a minimum of 4 exposure periods (30 minutes, 1 hour, 4 hours, 8 hours). In certain instances, AEGL values for a 10‐minute exposure period also will be developed. Each threshold value is distinguished by varying degrees of severity of toxic effects, as initially conceived by the AIHA ERP Committee, subsequently defined in the NAS' National Research Council Report, Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances, published by the National Academy of Sciences in 1993, and further refined by the NAC/AEGL Committee. To date, the committee has reviewed over 80 chemicals.
Using maximum experimental safe gap to select flame arresters
Authors: Britton Laurence G.
Published: April 2004

This article discusses the use and possible misuse of Maximum Experimental Safe Gap (MESG) in selecting deflagration and detonation flame arresters (DDAs). Gas mixtures having low autoignition temperatures or unusually wide flammable ranges might not behave as predicted on the basis of MESG, especially under restricted‐end deflagration conditions. When applied to DDA selection the Westerberg apparatus might prove to give a more reliable ranking of gas sensitivity than the IEC apparatus. If credit is taken for inert gases using the new MESG combination formula in NFPA 497 an incorrect DDA could be selected. An outline is given for a possible test program to elucidate the effect of gas mixture MESG on DDA performance.
Case history: A steam line rupture at Tennessee Eastman division
Authors: Lodal Peter N.
Published: April 2004

At approximately 1:07 PM on November 3, 1998, a 12'' branch 600 psig steam line on a pipe bridge near the center of the Tennessee Eastman Division (TED) plant ruptured catastrophically. A 36'' long section of the line upstream of a decommissioned venturi flow meter failed, resulting in a major steam leak. The leak led to the loss of 600 psig header pressure throughout the plant, resulting in the shutdown of all steam generation equipment, and the loss of production throughout most of the TED facility for a period of 5‐7 days.

Because this incident occurred in a section of steam piping over 30 years old, immediate concerns focused around the vulnerability of the entire network to similar failures. This paper discusses the resulting root cause analysis (RCA), and the surprising results obtained from the analysis of the ruptured pipeline, which uncovered a root cause completely different from that assumed by the team at the start of the investigation.
A model of indoor releases with recirculating ventilation
Authors: Woodward John L.
Published: April 2004

Modeling indoor dispersion is an important problem for risk analysis used to justify design improvements that increase safety. Of particular interest is a method to estimate what fraction of the volume of a room could have flammable concentrations when the source rate is too weak to fill the entire room. An analytic model is described here that allows a time‐varying source rate such as typically occurs with an evaporating liquid pool. The model allows automatic increases and decreases in the ventilation rate and/or fresh air makeup ratio such as could be activated by a gas sensor system. This provides a design tool for such gas sensor systems. An approximate approach is developed to estimate the effects of imperfect mixing, such as can occur with density stratification or dead zones. Two options are described, a dead zone model and a “bypass” model.
The pros and cons of shelter‐in‐place
Authors: Mannan M. S. , Kilpatrick D. L.
Published: April 2004

Recently shelter‐in‐place has received a lot of attention regarding its effectiveness as an emergency response measure. While proponents feel that it is an effective measure, opponents are equally confident that shelter‐in‐place itself could represent a threat and be the cause of injuries, fatalities, and general loss of comfort. This paper provides an overview of the current knowledge on shelter‐in‐place, procedures for effective shelter‐in‐place, and factors that should be taken into account in recommending shelter‐in‐place. The authors argue that shelter‐in‐place should not be the only alternative considered by emergency response planners. However, at the minimum, shelter‐in‐place should be considered as a high‐level element in the hierarchy of emergency response options available to emergency response planners, emergency responders, and incident commanders.

Within this paper are summaries cataloging the effectiveness of shelter‐in‐place. It demonstrates the circumstances in which shelter‐in‐place can be a viable response measure. Also included are the initial steps towards development of a decision tree that can be used to evaluate the many options that safety managers are faced with. While all of these protective methods are viable, one method may be preferred over another in certain circumstances.
Zero period process—a description of a process to zero injuries
Authors: Squire Richard H.
Published: April 2004

At the Dupont plant, located in Belle, West Virginia, we have marked three years without an OSHA recordable injury. While earlier speculation suggested that a process might exist to accomplish this sustainable level of performance, the road to actually developing the needed processes was not at all straightforward. We have summarized this work in the paper.
Ammonia plant NII: Explosion of hydrogen in a pipeline for CO2
Authors: Pande John Oscar , Tonheim Jan
Published: April 2004

On Sunday, April 13, 1997, the transfer pipe for CO2 gas from Ammonia Plant NII exploded. There were no injuries, but 850 meters of the line was totally destroyed and a large number of glass windows were broken.

The line was temporarily out of service, and the investigation team concluded that:

the trip system had been disabled prior to the explosion,

hydrogen enriched gas had entered the pipe line,

nitrogen purge had not been effective,

air had leaked into the line and formed an explosive mixture, and

the mixture had ignited.
Using quantitative methods to evaluate process risks and verify the effectiveness of PHA recommendations
Authors: Wallace Stephen J.
Published: April 2004

Federal regulations and internal factors mandate that managers of chemical processes ensure that the process is operating in a safe manner. Traditionally, some form of a qualitative Process Hazard Analysis (PHA) has been used to evaluate the condition of the process, comply with federal regulations (specifically OSHA 1910.119 and EPA 40 CFR 68), and develop recommendations to ensure safe operation in the future. However, by extending what is required, actual process risks can be quantified, recommendations can be better prioritized, and money spent on safety can be allocated appropriately.

One approach that has successfully been used to satisfy all these objectives is outlined in this paper. It requires a combination of qualitative analysis extended by quantitative analysis. Information is initially gathered by a team familiar with the process and safety analysis techniques, actual risks are determined, recommendations are developed as necessary, and the expected success of implementing a particular recommendation is evaluated.
Safety aspects in urea plants: The stamicarbon Y2K update
Authors: Meessen J. , Donker R. , Vlake H. , Van Den Aarssen A.
Published: April 2004

Adding oxygen to the urea process has proven to be an effective and reliable way to minimize corrosion to the stainless steels used in plants. However since the introduction of this technology in the early 1950s, the fire and explosion risk associated with oxygen (air) in urea synthesis has required special attention in design and operation. Experience and knowledge on safer operating procedures has grown over the years, through experience gained in operating plants, as well as through fundamental research. At the same time, the chemical process industry has needed to comply with stricter safety regulations. Let there be no doubt, Stamicarbon thinks these increased demands on safety related topics certainly are justified. The combination of growing insight on the one hand, and increasing demands on the other hand, justifies a regular update of safety guidelines and standards.
Case histories of pump explosions while running isolated
Authors: Giles Douglas S. , Lodal Peter N.
Published: April 2004

Standard industrial centrifugal pumps that isolate process material (i.e. “deadheaded” with both suction and discharge valves closed) inside the pump casing can explode catastrophically if the pump is inadvertently started and left running.

Case histories and lessons learned at Tennessee Eastman Division (TED) involving pump explosions while running isolated will be presented in this paper. Case histories involve both combustible and non‐combustible process streams where the pump was inadvertently started and allowed to run isolated until the process material heated up and built enough pressure to rupture the pump housing creating a BLEVE (Boiling Liquid Expanding Vapor Explosion). Incident learnings will be presented for each case.
Dust explosion case study: “Bad things can still happen to good companies”
Authors: Pickup Richard D.
Published: April 2004

In recent years, the general level of awareness of dust explosion hazards within the process industries has greatly improved. In light of this, many companies have incorporated recognized techniques to prevent or mitigate the damaging effects of dust explosions into their designs and procedures. However, a recent investigation of an incident at an agrochemical formulation facility demonstrates, unfortunately, that “bad things can still happen to good companies”.
Application of fire protection measures to new and complex chemical facilities
Authors: Slye Orville M.
Published: April 2004

Originally this paper was intended to be a review of fire protection measures and requirements for new and complex facilities. However, on reflection, I realized that the protection requirements for new complex facilities were really no different than for other facilities in the chemical industries. Fire safety challenges are equally daunting in all segments of the industry. This paper reviews methods commonly used to design fire protection measures for chemical plants, and proposes the use of performance‐based fire protection analysis and design as an alternate to specification design methods.

Loss prevention techniques have been partially eclipsed by process safety management efforts launched to meet OSHA Process Safety Management (PSM), and EPA Risk Management Program (RMP) requirements. But, fire protection, prevention, and explosion safeguards must continue to be included in plant design and operations to assure overall plant safety.
Process hazard analyses of control and instrument systems
Authors: Freeman Raymond A.
Published: April 2004

The OSHA process safety management (PSM) and EPA risk management program (RMP) standards require that process hazards analyses (PHAs) be performed on processes that contain listed toxic or flammable chemicals. A number of PHA techniques are listed in both standards that can be used to satisfy this requirement. Typical PHA studies use analysis techniques, such as hazard and operability (HAZOP), what‐if, and checklists, to review potential hazards, such as deviations from normal process conditions of flow, temperature, pressure, etc. The influences of control and instrument system failures on process system safety are usually considered indirectly. This paper reviews some of the considerations needed to conduct a PHA that includes control and instrument system failures. Information on (1) how to organize the review analysis team, (2) what type of documentation is needed, and (3) the special considerations needed in a control and instrument system review are included in this paper. The wide use of advanced programmable and electronic systems in the chemical process industry introduces a number of special considerations that must also be included in a review. These considerations are also discussed in this paper.
Fault management analysis
Authors: Summers Angela E.
Published: April 2004

In the chemical process industries, intrinsically safe operations must be the process engineer's goal, but, in reality, it is often not feasible, either technically or economically. In these cases, safety instrumented systems (SIS) are often used to detect and respond to process risk. SISs have many components that must work as designed in order to mitigate potential hazardous incidents. Over the years, many of these components have evolved from simple electro‐mechanical devices to complex mechanical, electrical, and programmable devices. What makes these devices fail must be examined in order to understand how each component failure can propagate into fail‐safe and fail‐dangerous conditions.

This paper proposes the use of fault management analysis (FMA) for the assessment of proposed SIS designs. An FMA identifies not only the failure modes of each component, but also determines how to appropriately manage the identified failure. This paper demonstrates how proposed design, diagnostics, inspection, maintenance, and testing programs should be modified to improve the SIS performance.
Influence of turbulent flow conditions on the ignition of flammable gas/air‐mixtures
Authors: Horstmann Tilo , Leuckel Wolfgang , Maurer Bodo , Maas Ulrich
Published: April 2004

We investigated spark‐induced ignition of methane/air‐and propane/air‐mixtures under turbulent conditions in a pipe‐flow system where turbulence was increased by the use of grids. A laser‐doppler‐anemometer was used to characterize turbulence in the test facility. To determine the actual energy released by the spark ignition source, we measure delectrical current and voltage during spark discharge. The results show that turbulent fluctuations have the greatest influence on the ignition process, whereas the convective part of the flow (up to velocities of 40 m/s) exerts little influence. For numerical work, a one‐dimensional simulation program, including detailed chemistry and multi‐species molecular transport is used. It is shown that the main influence on the ignition is due to the rms‐value of turbulence. Further more, the influence of increased flow velocity on flammability limits, and of diff e rent spark duration times and macrolengths on the ignition process, are demonstrated.
Combustion safeguards test intervals—risk study and industry survey
Authors: Kauffman Jeff , Oakey Thomas L. , Price Kenneth , Johnson Robert W.
Published: April 2004

As standard practice, The Procter&Gamble Company tested combustion safeguards on a monthly basis. The study summarized in this paper examined the risk impact of varying the safeguard test interval. Among the consequences considered were fuel explosions, flue gas/burning outside a combustor, steam‐side overpressurization, water tube/fire tube rupture, and bringing the combustor down for testing when at full utilization. Abnormal situations in lightoff, continuous operation, and shutdown modes were modeled using fault tree analysis. Gate‐to‐gate and common mode calculations were implemented in an Excel® spreadsheet for determining the likelihood of each consequence, the overall loss rate, and the effect of changing the test interval. Results of the study indicate, for the particular combustor selected for analysis, increased risk if safeguards are tested either more than once a month or less than once a year. Survey results from 25 Council of Industrial Boiler Operators (CIBO) member companies indicated that annual testing of combustion safeguards is the predominant industry practice. Procter&Gamble is in the process of changing its standard practice worldwide to a three‐month or sixmonth combustion safeguards test interval, depending on the type of combustor.
Application of relational chemical process safety databases for lowering mean failure rates
Authors: Al‐Qurashi Fahad , Sharma Gaurav , Rogers William J. , Mannan M. Sam
Published: April 2004

This paper proposes a linkage among accident, failure rate, and reactivity databases for process safety applications. The objective of the relationships among these databases is to bring all relevant information on both equipment and chemicals into one relational database. Such a database will make possible a better understanding by plant personnel about the reliability of plant equipment and the potential danger of process chemicals. Consequently, accidents should be reduced.

This research shows that relationships can be established among the three databases, and the examples presented demonstrate how it is done. Improving equipment reliability, calls for an approach of meeting the mean of failure rate data rather than the “industry best practice.” Modifications of current accident databases are proposed to develop effective relational databases that can help improve the safety performance of industry.
Two hundred years of flammable limits
Authors: Britton Laurence G.
Published: April 2004

This article discusses flammable limit test methods with reference to the past 200 years of research. Critical examination is made of the various pressure rise criteria currently used to determine whether flame propagation has occurred in closed test vessels. Of these, the most appropriate, with respect to vessels of 5‐20 liters volume, is judged to be the “net 7%” pressure rise criterion described in ASTM E‐2079. Since the tests are typically carried out in spherical vessels with central ignition, only a small fraction of the limit mixture burns and consequently a small pressure rise criterion must be used. Also, it is impossible to determine the product distribution for near‐limit flames. A small pressure rise criterion may cause the flammable range to be overestimated, particularly at the upper limit. For non‐routine and standardization purposes at least, use of a tall, large diameter, cylindrical vessel with bottom ignition is suggested.

European test methods are creating a database of flammable limit values outside the range of compositions at which flames can self‐propagate. The objective of flammable limit measurement should be to obtain close agreement with large‐scale observations and, ultimately, with theoretical models for self‐propagating flames. It is recommended that “flammable limits” measured using DIN 51649 and European Standard prEN1839 (or closed vessel methods striving to obtain values consistent with these) not be mixed with the existing database because they correspond to fuel concentrations that do not support flame propagation in any orientation.
Using heats of oxidation to evaluate flammability hazards
Authors: Britton Laurence G.
Published: April 2004

The heat of oxidation is the net heat of combustion per mole of oxygen consumed. For complete combustion it is given by “ΔHC/S” (kcal/mol oxygen), where “ΔHC” is the net heat of combustion (kcal/mol fuel) and “S” is the stoichiometric ratio of oxygen to fuel as written in the stoichiometric equation. Although previously unrecognized, the heat of oxidation “ΔHC/S” is the single most powerful parameter for evaluating the flammability hazards of fuels.

This article derives and discusses eight simple rules for estimating flammability parameters of single or mixed organic fuels in air under atmospheric conditions. The rules apply to fuels containing combinations of C+H+O+N atoms that burn to carbon dioxide plus water. Apart from the trivial First Rule, each rule is expressed in terms of the heat of oxidation.

Two Rules are presented for lower flammable limit (LFL) estimation. The First Rule is approximate and requires only the stoichiometric ratio of oxygen to fuel “S.” Although it outperforms Lloyd's Rule, it similarly overestimates the LFLs of energetic fuels such as acetylene and ethylene oxide.

The Second Rule requires both “S” and the net heat of combustion “ΔHC.” It is shown that the LFL is inversely proportional to the product of heat of combustion and heat of oxidation. LFL predictions are typically within experimental error of reported values, including energetic fuels such as acetylene and ethylene oxide.

The Third Rule shows that lower limit flame temperatures decrease linearly with increased heat of oxidation and increase stepwise between hydrocarbons and other organic fuels containing oxygen and nitrogen atoms.

The Fourth Rule shows that the Limiting Oxygen Concentrations (LOCs) of non‐decomposable fuels decrease with the inverse square of heat of oxidation. It is proposed that the optimum fuel concentration at the LOC is related via diffusivity ratio to the stoichiometric concentration. A fuel‐oxygen Cartesian flammability diagram is suggested for presenting LOC data.

The Fifth Rule shows that maximum flame temperatures increase linearly with increased heat of oxidation and decrease stepwise between hydrocarbons and other organic fuels containing oxygen and nitrogen atoms.

The Sixth and Seventh Rules address fundamental burning velocity “Su” and lowest minimum ignition energy (LMIE), second order polynomial expressions being presented for easily calculating these parameters. It is shown how the calculated Su can be used to estimate normalized rate of pressure rise “KG” data. It is also demonstrated that many published LMIE and quenching distance values are too high.

The Eighth Rule gives a tentative expression for quenching distance, which decreases linearly with increased heat of oxidation. A scheme is presented for ranking fuel hazards in terms of heat of oxidation. Demarcations are made in terms of Su, LMIE and Class I NEC and Zone Groups. It is shown how the approach might be extended to deflagration and detonation arrester selection.
Business continuity management: Advanced life support for companies
Authors: Fries William J.
Published: April 2004

If not anticipated and planned for properly, interruption of a production process, or a cutoff of products from the market, can have potentially fatal consequences.
Software‐implemented safety logic
Authors: Summers Angela E.
Published: April 2004

Process industries rely on various safeguards to minimize the potential and consequence of hazardous incidents. Active safeguards, such as safety instrumented systems (SIS), fire and gas systems, and emergency vents, use sensors to detect process upsets, then take action to bring it to a safe state.

Many users implement active safeguards using programmable logic controllers (PLCs). The PLC uses a combination of hardware and software to respond to inputs (process variables) by generating outputs (safety actions). The execution of the safe state logic is dependent on the application program integrity, which may be developed by the PES vendor, engineering contractor, system integrator, or the user. Successful implementation and thorough verification of the application program is essential for correct SIS operation.

This paper will first discuss the various types of SIS software, including full variability, limited variability, and fixed programming languages. It will then look at proposed application program requirements, and guidelines in the international process industry sector standard, draft IEC 61511.