bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fire exposure of liquid‐filled vessels
Authors: Simpson Larry L. 
Published: April 2004

AbstractPressure vessels in the chemical industry generally have top‐mounted pressure relief valves (PRVs) sized to handle fire exposure and other possible scenarios. Designers usually assume that the fire scenario causes liquid to boil and vapor to vent, regardless of the initial liquid level. Under some circumstances, however, a high liquid level, together with thermal expansion, can result in a vessel being full of liquid when the PRV opens. If so, the initial fluid discharged through the PRV would be a two‐phase gas‐liquid stream.This paper analyzes non‐reactive phenomena occurring during the heat‐up and venting process in non‐agitated liquid‐filled pressure vessels. A new criterion is developed to determine if the vapor‐venting sizing assumption is justified. Results from several cases show that pressures in most liquid‐filled vessels sized for vapor‐only flow will be below the ASME Code‐allowable values during fire exposure. Hence, the common industry practice of ignoring two‐phase flow when sizing fire cases is usually justified.
Lessons learned from an explosion in a large fractionator
Authors: Woodward John L. , Thomas J. Kelly , Kelly Brian D. 
Published: April 2004

AbstractDuring plant start‐up, a critical interface exists at block valves located at battery limits of process units. A relatively small leak at a battery‐limit isolation point was established as the source of gas that caused an explosion in a 26‐foot diameter fractionator on a Fluid Coker nearing the end of a maintenance turn a round. This incident could easily have occurred in any modern oil refinery or chemical plant. This paper shares the technology and learning associated with small release scenarios that are often overlooked in large‐scale plant operations.The explosion event did not damage the fractionator shell, but displaced all but two of the sieve trays in the column, and produced minor damage in the overhead condensers and receiver drum. Importantly, the consequent down‐time resulted in a major production loss. Damage analysis supports the proposition that a deflagration occurred in the top portion of the fractionator involving under 50 lbs. of fuel. It is believed that relatively small leaks, persisting over a period of a few hours, supplied the required amount of fuel. The accident investigation identified multiple potential pathways whereby natural gas leaking past battery limit block valves could have reached the fractionator.This incident highlights the importance of securing leak tight connections between active and inactive sections of process systems. As a result of this experience, several procedural and organizational reforms have been instituted.
IEC 61508/61511—Pain or gain?
Authors: Timms Clive Roger 
Published: April 2004

AbstractThe introduction of IEC 61508 provided safety system practitioners with the first internationally accepted generic benchmark policy for safety‐related systems. However, many practitioners find the way in which the standard is often presented and promoted quite intimidating. But, there is no need to be intimidated. The grassroots rationale of the standard is fundamental common sense, and there have been significant developments in practical software aids that remove the pain.An optimal design can lead to considerable capital cost savings from focused Safety Integrity Level (SIL) assessment, component selection, and logic simplification. Experience shows that up to 40% savings can be achieved with the aid of software tools at the design stage.Full life cycle considerations also require alignment of a design with appropriate maintenance and testing strategies. This can afford significant opportunities to reduce maintenance and testing costs, production deferment, and the avoidance of nuisance trips. These opportunities become very achievable with the aid of software tools.Software tools can help to achieve these not insignificant benefits by aiding design, and setting optimal testing and maintenance calculations to meet SIL requirements.
Investigation of catastrophic vessel overpressurization
Authors: Long Lisa A. 
Published: April 2004

AbstractThis paper summarizes the U.S. Chemical Safety and Hazard Investigation Board's investigation of a 1998 catastrophic vessel overpressurization incident at a petroleum separation facility near Pitkin, Louisiana. Sonat Exploration Company (now El Paso Production Company) owned the site. Two separation trains were set up to produce crude oil and natural gas from a high‐pressure, three‐phase mixture of crude oil, natural gas, and water. Employees were in the process of purging a pipeline when a separation vessel was overpressurized and catastrophically failed. It ruptured and released natural gas, which ignited and produced a large fireball. Four workers were instantly killed, and nearby tanks and piping were damaged. The lack of formal engineering design reviews and hazard analyses, adequate pressure relief devices, and written operating procedures for each phase of facility operations were identified as root and contributing causes of the incident.
The survivability of steel and aluminum 33.5 pound propane cylinders in fire
Authors: Birk A. M. , Vandersteen Jonathan D. J. 
Published: April 2004

AbstractAll pressure cylinders in North America used for liquefied petroleum gases (LPG) must meet the standards set by the Compressed Gas Association (CGA), regardless of whether they are made of steel or aluminum. However, there is anecdotal evidence from accidents that suggests that an aluminum propane cylinder is much more likely to fail than a steel one when exposed to fire in an accident. In order to test and quantify this, a series of fire tests were performed on standard 33.5 lb (DOT 4E240) propane cylinders. Three aluminum cylinders and three steel cylinders were tested under three different fire conditions, covering a range of fire engulfment severity. In all cases, the cylinders were horizontal and the fire was directed onto the side and top of the cylinders. In matching tests, all 3 aluminum cylinders failed in less than 10 minutes, including one boiling liquid expanding vapor explosion (BLEVE), while all 3 steel cylinders did not fail even after more than 40 minutes in the fire. This paper presents the results and an analysis of the fire test data.
Mitigation of backdraft with water mist: A reduced‐scale experimental study
Authors: Weng W. G. , Fan W. C. 
Published: April 2004

AbstractBackdraft is a special fire behavior in a limited‐ventilation building. It can develop from fires of either ordinary combustibles, or ignitable liquids that become oxygen‐starved, yet continue to generate a fuel‐rich environment. If abundant fresh air is abruptly supplied by opening a door or breaking a window, the hot gas in this vitiated building will rapidly combust and a fireball and blast wave will take place. Backdraft can occur abruptly with powerful destruction, which may cause fatalities and the collapse of buildings. In this paper, the results of a reduced‐scale experimental test series using water mist to mitigate backdraft are presented. This reduced‐scale compartment (length x width x height with 1.2 m x 0.6 m x 0.6 m) was fitted with a door end opening geometry (width x height with 0.2 m x 0.4 m). Water mist was generated by a downward‐directed pressure nozzle operated at pressure of 0.2 MPa. The experimental results show that water mist is an effective mitigating tactic able to suppress backdraft in a building fire, primarily by means of reducing unburned fuel mass fraction, rather than by a thermal mechanism of cooling.
Dynamic model‐based technique for detecting faults in a chemical reactor
Authors: Chetouani Yahya , Mouhab Nordine , Cosmao Jean‐Marie , Estel Lionel 
Published: April 2004

AbstractIn this paper, we present a method for detecting faults that can appear in some parts of a chemical plant. This method is based on statistical information generated by the Extended Kalman Filter (EKF) technique and is designed to reveal any drift from the normal behavior of the process. Originally developed for linear systems, our contribution to this method consists in extending it to unsteady state nonlinear systems, such as stirred reactors in the presence of exothermic chemical reactions. We examined the abnormal behavior of a chemical reactor due to one fault in its control parameters. An abrupt variation of cooling flow rate has been studied experimentally. The objective of this experimental study is to detect the presence of such faults online, and to pinpoint the moment one occurs.
On the ability of process hazard analysis to identify accidents
Authors: Baybutt Paul 
Published: April 2004

AbstractProcess hazard analysis (PHA) has become the standard way of identifying possible accidents in processes. However, despite the large number of studies that have been performed since OSHA's Process Safety Management standard was issued in 1992, accidents still occur. When this happens the effectiveness of PHA and the quality of the studies performed may be questioned. Litigation can arise, and attorneys may try to make the case that someone was negligent because the PHA did not identify the accident that occurred.While it is possible that PHAs may miss accident scenarios owing to the quality of the study performed, there are other reasons why scenarios may not be identified. This paper identifies and describes such reasons.
Young children learning about living things: A case study of conceptual change from ontological and social perspectives
Authors: Venville Grady 
Published: April 2004

AbstractAlthough research from a developmental/psychological perspective indicates that many children do not have a scientific understanding of living things, even by the age of 10 years, little research has been conducted about how students learn this science topic in the classroom. This exploratory research used a case‐study design and qualitative data‐collection methods to investigate the process of conceptual change from ontological and social perspectives when Year 1 (5‐ and 6‐year‐old) students were learning about living things. Most students were found to think about living things with either stable, nonscientific or stable, scientific framework theories. Transitional phases of understanding also were identified. Patterns of conceptual change observed over the 5‐week period of instruction included theory change and belief revision as well as reversals in beliefs. The predominant pattern of learning, however, was the assimilation of facts and information into the students' preferred framework theory. The social milieu of the classroom context exposed students' scientific and nonscientific beliefs that influenced other individuals in a piecemeal fashion. Children with nonscientific theories of living things were identified as being least able to benefit from socially constructed, scientific knowledge; hence, recommendations are made for teaching that focuses on conceptual change strategies rather than knowledge enrichment. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 449–480, 2004
Study of additive compatibility with poly(vinyl chloride) (PVC). 2: Dynamic mechanical analysis of PVC lubrication by stearic acid and its derivatives
Authors: Fisch Michael , Bacaloglu Radu 
Published: April 2004

AbstractThe glass transition temperatures of PVC containing stearic acid derivatives as lubricants have been used to define two new parameters of lubrication: the saturation concentration and the efficiency constant. The saturation concentration represents the maximum amount of lubricant compatible with PVC in a specific formulation. The lubricant molecules are associated with the surface molecules of the PVC primary particles or are in the interstitial space between them. The use of lubricants at significantly lower concentration than the saturation concentration ensures their permanence in the polymer. They then act as internal lubricants reducing the viscosity of the melt. The use of lubricants at much higher concentrations than saturation concentration leads to formation of lubricant pools between PVC primary particles. Increased temperature or longer time ensures the release of lubricants from these pools at the surface of the polymer giving the lubricants an external character. At a normal usage of 0.5 to 1.5 phr (approximately 1.6–5 meq stearate) to 100 g PVC, methyl, barium and calcium stearates may be considered internal, aluminum and sodium internal/external, zinc, lithium, magnesium stearates and stearic acid itself external lubricants.
Materials and testing for extrusion of RPVC construction products
Authors: Rapacki Steven R. 
Published: April 2004

AbstractRigid PVC extruded construction products take many forms. Typical are house siding, window profiles, storm doors, pipe, fencing, and various accessory items generrally used for installation. In addition to these solid products, foam or cellular rigid PVC materials are entering the marketplace as substitutes for the traditional solid materials, or allowing PVC to capture other maintenance free applications; typical forms now in use include interior molding profiles and foam core pipe. This article focuses on the formulation ingredients constituting the articles mentioned above, how they are put together and influence the manufacturing process and final product, and how they can be tested to determine fit to the application requirements.
FR characteristics of phosphate ester plasticizers with inorganic additives in PVC
Authors: Moy Paul Y. 
Published: April 2004

AbstractTwo common approachs to flame retard flexible PVC are phosphate ester plasticizers and antimony oxide. When used individually, each displays excellent flame suppressing characteristics. However, the combination of the two has been reported to show lower than expected flame resistance. Zinc borate plays a synergistic role with mixtures of phosphate ester plasticizers and antimony oxide, producing one of the most effective FR composite in this study. A review of this behavior in various PVC formulations is presented.
Vinyl foam: Effect of density on physical properties
Authors: Patterson John 
Published: April 2004

AbstractThe technology of extruding rigid viyl foam has grown substantially over the last 10 years. Formulation additives, tooling and processing expertise have made possible a variety of applications such as profile, sheet, and foam core pipe. Many PVC foam manufactures are interested in reducing the density of their products to reduce costs and achieve lighter weights. The properties, however, are very dependent on the density of the foam product. A fundamental understanding of the relationship of physical properties to foam density is the objective of this paper, along with looking at ways to improve them.
Scale effects upon morphology development during mix melting of multiphase polymer blends in ZSK extruders
Authors: Yu Dong‐Woo , Esseghir Mohammed , Curry John 
Published: April 2004

AbstractReplicate experiments were performed on ZSK‐30 and ZSK‐40 split barrel extruders concerning structure developments from PS‐PE pellet blends during the melting process. PS is the minor phase. PE grades were choosen to accommodate viscous and thin matrix phase viscosities. The large extruder displays a more diverse cross channel structure and retarded phase development for some blends. Inferior dispersion is especially obvious in the larger extruder when processing low viscosity matrix blends. Similar phase development occurs in the extruders for high viscosity matrix blends.
Development of a mathematical model for the calculation of the pressure drop in extrusion dies
Authors: Lang U. , Michaeli W. 
Published: April 2004

AbstractAnalytical approaches for calculating the pressure drop in extrusion dies are limited because they are only applicable in ideal flow channel geometries. In finite element calculations the pressure drop in different flow channels was determined. Parallel the cross section of those geometries was calculated, transformed into the ideal form of a slit or circle, and analytical calculations were done. From the results a correction function was derived. This enables realistic pressure drop calculation by applying simple analytical equations.
Predicting maximum field service temperatures from solar reflectance measurements of vinyl
Authors: Hardcastle Henry K. 
Published: April 2004

AbstractVinyl products continue penetrating Western U. S. markets. Vinyl products may show unacceptable heat distribution when installed in Western environments even after demonstrating a long tradition of acceptable heat build performance in Eastern U. S. environments. This paper presents a methodology for predicting maximum field service temperatures from solar reflectance measurements. Solar reflectance data (ASTM E‐903 and E‐892), field measurement data and a predictive model for a variety of vinyl systems are shown. This methodology may be used in addition to ASTM D‐4803 and is not limited to vinyl materials.
New benzoate plasticizers for polyvinyl chloride: Introduction and performance example
Authors: Arendt William D. , Lang Jiamin 
Published: April 2004

AbstractTwo new unique benzoate ester plasticizers that will offer the vinyl formulator improved performance have been developed. One is an excellent solvator that will yield lower plastisol viscosities than existing plasticizers. The other will provide an excellent alternate with low volatility. The new products provide expanded performance utility over existing benzoates and phthalates on a global basis. Basic plastisol performance data and an example of use in a specific application, vinyl leathercloth, are presented. The data demonstrates that these blends are compatible, effective high solvating plasticizers and are performance alternates for plastisols and other polyvinyl chloride applications.
Extraction resistant polymer stabilizers
Authors: Gray Robert L. , Lee Robert E. , Neri Carlo 
Published: April 2004

AbstractA new generation of polysiloxane based polymer stabilizers is examined. The flexibility and versatility of polysiloxane backbones have allowed the development of a family of products that provide outstanding radical trapping efficiency, an unexpected resistance to extraction, and a high degree of compatibility in certain polymeric systems. Functionalization with graftable moieties results in a product that can be chemically bound to the polymer itself. The key to success in this work was optimizing the balance of graft linkages and mobility of the stabilizer chain.
New trends in polymer stabilization
Authors: Solera Peter 
Published: April 2004

AbstractPolymer stabilization has been an active area of research and development for several decades. In this review, advances in phosphite chemistry are discussed with regard to hydrolysis resistance and color retention. The use of lactones as carbon centered radical traps is reviewed with examples showing the increase in performance over traditional base stabilization systems. Discoloration issues arising from hindered phenolic antioxidants are outlined, and, N,N‐dialkylhydroxylamine chemistry is reviewed as a means of avoiding phenolic discoloration while providing polymer protection. Color fading in demanding fiber applications is explored as well as a new stabilizer designed for color retention. The elimination of acid‐base interaction with NOR hindered amines is considered especially as it pertains to acidic polymer applications such as flame retardant end uses and agricultural films. Hindered amine stabilization chemistry and NOR performance data are discussed.
Properties of a thermoplastic elastomer derived from polyacrylate/PVC
Authors: Rehm Torsten 
Published: April 2004

AbstractThe polymerization of vinyl chloride in the presence of suitable elastomer dispersions yields so‐called PVC graft polymers. These may be processed on standard PVC equipment into flexible articles having a high mechanical strength and good indentation recovery. The ultimate physical properties are governed largely by the separation during processing into PVC‐rich and elastomer‐rich phases. For a polymer of poly(butyl acrylate) and PVC, this separation is examined by means of dynamic mechanical analysis (DMA). A method is presented by which it is possible to quantitatively classify the PVC molecules on the basis of grafted and ungrafted fractions as well as their respective size of the domains. The method allows the influence of processing conditions on stiffness, hardness, tensile strength, and elongation at break to be explained. Furthermore, reversible and irreversible property changes are shown to occur during reprocessing of test specimens.
Accelerated degradation of highly loaded polypropylene
Authors: Benavides R. , González‐Hernandez R. , González‐Cantú M. C. , Reyes‐Vielma B. , Billingham N. C. 
Published: April 2004

AbstractThe accelerated aging of six formulations of polypropylene highly loaded with calcium carbonate and containing a surfactant additive (stearic acid) as well as an ultraviolet (UV) stabilizer was studied. Degradation was followed by measuring mechanical properties (elongation percentage and impact resistance), the dynamic mechanical behavior and some chemical changes such as molecular weight and carbonyl group formation along with oxidation temperatures, found by chemiluminescence. The addition of 30 phr of filler to the polymer reduced the stability of the mixture, and the stearic acid used to treat the filler enhanced this effect considerably. On the other hand, the addition of the photostabilizer controlled to some extent such negative effects, though not completely. The most stable formulation was the polypropylene containing only the UV stabilizer.
Low‐melting sulfate glasses as additives to semirigid PVC and their flame retardant and smoke suppressant properties
Authors: Tian Chunming , Wang Hai , Ma Zhiguang , Guo Huazhi , Xu Jianzhong 
Published: April 2004

AbstractThe role of low‐melting sulfate glasses (LMSG) as additives on the flame retardant and smoke suppressant properties of semirigid poly(vinyl chloride) (PVC), as well as the mechanism for flame retardancy and smoke suppression, were studied through the Limiting Oxygen Index (LOI) test. Smoke Density Rating (SDR) test, DTA‐TG, and SEM. The results show that the LMSG have good smoke suppressant properties. When the PVC compound contains 40 parts of LMSG, the SDR value will be reduced by about 45%. The Cu2+, Zn2+, Mn2+, and Ni2+ sulfates, as well as MoO3, cause PVC to crosslink and form char, and the melt can protect not only the char formed during combustion and thermal degradation, but also undecomposed polymer. That is the main mechanism for flame retardation and smoke suppression when the additives melt. The mechanical properties of the PVC compounds containing different levels of LMSG were also studied.
Fire and flame retardants for PVC
Authors: William Coaker A. 
Published: April 2004

AbstractThe flammability performance of PVC plays a significant role in its selection for many applications. Its relatively high chlorine content (56.8%) makes it more resistant to ignition and burning than most organic polymers. In the case of flexible PVC, the plasticizers that contribute flexibility in most instances detract from its resistance to fire. To meet specifications such as oxygen index, heat release, smoke evolution, or extent of burning in cable tests, flame‐retardant (FR) and smoke‐suppressant (SS) additives are often incorporated. Synergistic combinations of FR and SS additives help PVC formulations meet many stringent FR specifications cost effectively.