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Organisationseinheit der BAM
Eingeladener Vortrag
- nein (34)
Rückendeckung
(2013)
Neben herkömmlichen Stahlflaschen, die seit Jahrzehnten in fast unveränderter Bauform für Flüssiggase (Propan-Butan-Gemische) eingesetzt werden, etablieren sich immer mehr Flaschen aus Faserverbundwerkstoffen (GFK) mit einer geringeren Masse. Die Bundesanstalt für Materialforschung und -prüfung (BAM) wurde beauftragt, das Verhalten dieser Gasflaschen unter den extremen Bedingungen eines Unfallfeuers zu untersuchen. In einem Brandprüfstand der BAM auf dem Testgelände Technische Sicherheit (TTS) in Horstwalde wurden deshalb beide Typen von Propangasflaschen einem simulierten Unfallfeuer ausgesetzt.
More than 400 Mt of dangerous materials are transported in Germany every year, of which 150 Mt are by road. Tank containers, tank vehicles and rail tank cars are used for the carriage of dangerous goods in large quantities. Data on the operating life of tanks are only available, in practice, to a minor degree. They are only partly published, mainly after accidents.
The BAM-List - Requirements for Tanks for the Carriage of Dangerous Goods, which has compatibility evaluations of metallic and polymeric materials, has been the basis for substance-related prototype approvals for tank containers and portable tanks designed for the carriage of dangerous goods by the BAM since publication of the first edition in 1989. These data are also used for the approval of rail tank cars and road tank cars and are used as a source of knowledge not only in Germany but also worldwide.
Tank leakages caused by tanks or rail tank cars being made of tank and sealing materials which are not resistant to the fill goods are avoided by using the material resistance data of the BAM.
Corrosion damage is among the main causes of damage. Uniform and non-uniform area corrosion without mechanical stress in aqueous substances is one of the most frequent types of corrosion during the transport of chemicals in tanks. Much damage by pitting corrosion occurs during the transport of substances containing chlorides or substances which separate chloride ions in the presence of moisture.
Operational stresses are caused by the effects of both the road and the dangerous goods being transported. Mechanical damage often results from long-term overstressing and occurs after longer operating times.
Operational failures cause damage which may appear during the service of tank containers, road tank cars or rail tank cars. The damage results from the inattention of employees when opening and closing the valves. Traffic accidents also cause damage to tanks and frames.
Many cases of damage are due to weld area cracks resulting from four basic errors in construction, material, manufacturing and operation. Manufacturing errors can be undetected and the starting point of cracks which only grow under service conditions.
Manufacturing errors result from variations in measurement and design, fittings, state of surface (hardness, abrasiveness) and mechanical surface damage (scratches, cracks). Incorrectly welded joints and errors during mechanical deformation are typical mistakes when installing the component parts. Variations in the wall thickness or combinations of different materials lead to manufacturing errors too. A lot of tanks are not used for the transport of dangerous goods before the end of their service life as they do not fulfil the revised technical safety requirements in the Dangerous Goods Regulations.
Predictions in the BAM-List based on literature data and corrosion test results are reflected in the service (operating) life. Rail tank cars made of carbon steel, for example, which are mainly used for the transport of petroleum products, can achieve a service life of 40 – 50 y.
Rail tank cars produced of austenitic CrNi- or CrNiMo-steel can reach an operating life of at least 30 y, whereby the corrosiveness of the transport substances plays an important role.
Steam generator (SG) tubes are part of the primary circuit of pressurised water reactors and therefore also part of the pressure retaining boundary components. Furthermore, steam generator tubes are the components which guarantee the separation between the primary and secondary circuits. Therefore the knowledge of the loss of tube integrity as soon as possible is an essential. Optimised nondestructive testing methods based on the eddy current array technique are used to find material degradation, especially intergranular stress corrosion cracks during the periodical in-service inspection. These methods are supported by the measurement of the leakage rate during operation based on radioactivity and Tritium measurement regarding a high crack grows. Shutdown criteria depending on leakage rates which are described in the operation procedures but there are no specifications about the conditions for the measured leakage. Is the leakage coming from a single crack or are there multiple cracks or is this the leakage of a critical crack. With the help of FE calculations answer about the uncertainties of leakage rate versus critical crack grows were found. Shutdown criteria must guarantee to avoid critical crack sizes, i.e. between the measured tritium activity and the critical crack size must be a safety gap.
Forschen für die Sicherheit
(2013)
Vergleich von Risiken
(2013)
Vielen Entscheidungsprozessen geht ein Vergleich voraus. Bei einem Produktvergleich werden dazu Kriterien festgelegt, etwa der Kaufpreis, die Güte, Haltbarkeit, Handhabung usw. Der Testsieger ist meist derjenige, der die am höchsten bewerteten Kriterien erfüllt. Voraussetzung für derartige Vergleiche ist also die Gleichartigkeit der Vergleichsobjekte. Risiken untereinander zu vergleichen ist komplizierter. Die Notwendigkeit von Risikovergleichen ergibt sich, wenn nur unklare Vorstellungen, z. B. über die Risiken einer neuen Transporttechnologie, existieren und keine Erfahrungswerte zur Verfügung stehen. Aus bekannten und akzeptierten Risiken soll mittels eines Vergleichs die Tolerierbarkeit eines (noch) unbekannten Risikos abgeleitet werden. Der Beitrag setzt sich mit der Problematik von Risikovergleichen auseinander.
Daten über Schadensursachen und die tatsächliche Nutzungsdauer der Tanks zum Transport von Gefahrgütern liegen nur in begrenztem Maße vor. Auf der Basis der Daten von Tankbaufirmen, Speditionen und Eisenbahnkesselwagen-Vermietgesellschaften wurde die durchschnittliche Lebensdauer von Tankcontainern, Tankfahrzeugen und Kesselwagen zur Beförderung von Gefahrgütern in der Praxis ermittelt und die Hauptschadensursachen analysiert. Korrosion, Risse an Schweißnähten, Gestaltungs- und Dimensionierungsfehler sowie fertigungs- und betriebsbedingte Fehler zählen zu den Hauptschadensursachen. Viele Tanks werden vor Ablauf ihrer Nutzungsdauer nicht mehr für den Transport von Gefahrgütern eingesetzt, da sie nicht mehr den geänderten gesetzlichen Anforderungen in den Gefahrgutvorschriften entsprechen. Die Voraussagen durch Literaturangaben und Ergebnisse von Korrosionsversuchen in der BAM-Liste – Anforderungen an Tanks zur Beförderung gefährlicher Güter – spiegeln sich in der Nutzungsdauer/Lebensdauer der Tanks wider.
Use of higher-alloyed metallic materials and duplex steels for transport tanks of dangerous goods
(2011)
Compatibility evaluations of selected metallic materials under the influence of dangerous goods are published in the BAM-List - Requirements for Tanks for the Transport of Dangerous Goods” as basis for substance-related prototype approvals for tank Containers designed for the carriage of dangerous goods.
There is a request of the tank manufacturing industry and transportation Companies to incorporate additional materials into the BAM-List, especially corrosion-resistant materials because of the large number of corrosive dangerous goods. One solution to solve corrosion Problems is to line the tank with a polymer, an alternative solution is the application of high-alloyed stainless steels and nickel-based alloys as there are 1.4529 (XINiCrMoCu 25-20-7, alloy 926), 1.4562 (X1NiCrMoCu32-28-7, alloy 31) and 2.4605 (NiCr23Mo16AI, alloy 59).
There is an interest to use cost-efficient steels with high strength values and concomitant adequate corrosion resistance such as duplex steel 1.4362 (X2CrNiN23-4).
This steel grade was originally developed as a substitute for the austenitic grades 1.4404 (X2CrNiMo17-12-2) and 1.4571 (X6CrNiMoTi17-12-2). Due to the lower content of the alloy elements nickel and molybdenum this duplex steel is a cost-efficient alternative to molybdenum containing austenite.
Due to the limited number of corrosion test results with welded test samples of these high-alloyed materials and the duplex steel under the influence of corrosive dangerous goods a comprehensive test Programme was performed with these materials in Cooperation with ThyssenKrupp VDM and Deutsche Edelstahlwerke GmbH. It can be concluded from the test results that the superaustenitic steels 1.4529 and 1.4562 as well as the nickel-based alloy 2.4605 are a really good alternative as tank materials for the transport of dangerous goods in comparison to the lining of the tanks. The nickel-based alloy 2.4605 shows the best resistance and is suitable as material for tanks transporting all tested corrosive substances. One exception is the temperature limit during the transport of hydrochloric acid.
The superaustenit 1.4562 is a resistant material with a wide ränge of application. Exceptions for use are: ammonium bifluoride, brine, 34 % calcium Chloride solution, hydrochloric acid, perchloric acid, 90 % 2-chloropropionic acid, nitrating acid with nitric acid content > 50 % and molten monochloroacetic acid. The alloy is limited suitable for allyl Chloride, aluminum Chloride, copper (II) -Chloride and ferric Chloride. The superaustenit 1.4529 showed the lowest resistance compared to the other two materials. This steel is not resistant in hydrochloric acid, perchloric acid, sodium Chlorite and sodium hypochlorite. The application is limited in the concentration ränge of aqueous Solutions of aluminum Chloride, copper (II) Chloride and ferric Chloride. Due to the reduced alloying content of the duplex steel 1.4362 (X2CrNiN23-4) compared to the austenitic CrNiMo-steels, a lower resistance especially in acidic media like formic, acetic or sulfuric acid was observed. Within the more than 7.000 substances contained in the BAM-List there is a large amount of dangerous goods such as hydrocarbons, alcohols, aldehydes, ketones, ethers, esters, and inorganic alkaline substances which have a large transport volume and do not corrode the duplex steel 1.4362 (X2CrNiN23-4).
The test results are included in the actual 11th edition of the BAM-List and therefore available for the costumer.
Im Gefahrgutrecht, insbesondere im Bereich der Gefahrguttanks für den Landverkehr, hat der Bezug zur technischen Norm aufgrund der Rechtsfortentwicklung eine fundamentale Bedeutung erlangt. Damit die Interessen der deutschen Tankhersteller genügend Berücksichtigung finden können, ist die kontinuierliche Mitarbeit der betroffenen Wirtschaftskreise in den nationalen und internationalen Normungsgremien erforderlich. Dieser Zusammenhang, der für den einzelnen Hersteller mit erhöhtem Aufwand verbunden ist, wird von den betroffenen Kreisen nicht flächendeckend wahrgenommen. Der Beitrag analysiert Gründe hierfür und macht Vorschläge zu leichten Korrekturen in der inhaltlichen Ausrichtung der Normung.
In-service inspection Atucha
(2011)
Degradation of material properties significant for lifetime extension of nuclear power plants
(2010)
The discussion about the right energy sources or alternative energy generation goes around the world, mostly in connection with green-house gas reduction. Therefore, some countries have started to consider extending operation of nuclear power plants. This demands an extensive plant life management as well as the knowledge of the degradation in material properties. The Basis Safety Concept (BSC) in Germany observed this circumstance. Still, lifetime extension is not an issue in Germany due to phase out of nuclear energy. Part of the BSC is the application of non-destructive examination (NDE) methods from the beginning, i.e. from component manufacture, to the end of life. The application of a NDE method to detect and size defects in components in nuclear power plants is presented. Some material properties and their degradation during increase of operation time are also in the focus of this paper.
In der Vergangenheit führte die Bundesanstalt für Materialforschung und -prüfung (BAM) zahlreiche Tankbrandversuche mit und ohne Sicherheitseinrichtungen durch. Dabei stellte sich heraus, dass Gastanks mit nicht ausreichend dimensionierten Sicherheitseinrichtungen bei einer äußeren thermischen Belastung innerhalb von 6 bis 10 min in Form eines BLEVE (Boiling Liquid Expanding Vapour Explosion) versagen können. Um die Feuerwiderstandsdauer eines Tanks zu erhöhen, besteht die Möglichkeit, den Tank u. a. mit einer sog. reaktiven Brandschutzbeschichtung zu versehen. Bei einer Temperatureinwirkung ab ca. 200 °C (produktabhängig) beginnt die Schicht aufgrund einer thermochemischen Reaktion aufzuschäumen. Die Tankwand wird dabei temporär vor einer weiteren schnellen Erwärmung geschützt.
Gashochdruckleitungen
(2012)
In Europe, tanks designed on different safety philosophies are used for transporting one and the same liquid dangerous goods (Krautwurst, 2011). Owing to this circumstance, the BAM was commissioned by the BMVBS to conduct a research project designed to analyse and assess the equipment of tanks. Furthermore in these project were researched some failure mechanism of pressure relief devices (PRD).
Based on the knowledge gained, possible solutions were worked out under safety-relevant aspects that would benefit tank transport by providing a lower hazard potential. Besides looking at the mode of operation and the construction of PRV, their blow-off characteristics and total flow rate are considered from a safety engineering point of view.
Based on in-depth studies, a concept for and the further approach to examinations of the failure limits of PRD, especially of spring loaded relief valves, was developed and comprehensively described in the report “The use of safety devices, particularly safety valves, on transport containers” (Pötzsch, Reich, & Jochems, 2011).
The purpose of this study was to investigate failure causes of safety valves by normal modes and accidental fire heat loads. A series of investigations for different influences using safety valves for tanks were obtained. Testing vibration modes and corrosion presents some design limits. Experimental study of a pressure vessel engulfing in fire identify significant design limits. The complete set of results provides direct information of fail-safe modes and discusses the usage.
How can the risk of a BLEVE be reduced? That is the main question based on different research projects. In various large scale fire tests fire protection coating systems were used of different manufacturers. The degree of the coating as well as the layer thickness and the processing were varied. These experimental configurations were partly tested with and without pressure relief valve. The pressure relief valves were not protected again the thermal Load from the test fire. The ambition is to find a minimum of the thickness from the fire protection coating witch delay a BLEVE up to 90 minutes. Here are given the most interested configurations of tanks in fire and a description of the test-rigs.
Dangerous goods are transported as air freight in commercial aircrafts. Using plastic jerrycans or plastic containers, liquids or gases can escape by leakage or permeation effects. Prior research by the German Federal Institute for Materials Research and Testing (BAM) showed that the lower explosion limit can be reached when transporting dangerous goods in sea-freight containers under normal transportation situations. This motivated the presented study of the transportation situation of dangerous goods in cargo compartments of commercial airplanes. The scope of this paper is to present the experimental method used for validating a numerical model for CFD (Computational Fluid Dynamics) simulations. The CFD model will be used in a future study to evaluate the potential risk from transporting dangerous goods.
The objective of this paper is to present the model mock-up of an aircraft cargo compartment and some examples of three dimensional velocity profiles of the air flow in the mock-up. The velocity profiles are calculated using numerical simulations and measured by Laser-Doppler-Anemometry (LDA) experiments. The mock-up is a generic model of a wide-body aircraft lower deck cargo compartment in a 1:10 scale. Geometry, air exchange rates and inlet as well as outlet flow conditions in the cargo compartment are modeled using realistic boundary conditions. The commercial CFD (Computational Fluid Dynamics) code ANSYS CFX 14 is used for numerical flow simulations applying RANS (Reynolds-Averaged-Navier-Stokes) equations and turbulence models. The turbulence models studied are the renormalization group k-ε-model (RNG), the Reynolds-Stress model by Launder, Reece and Rodi (LRR) and the SST-k-ω-model by Menter (SST).
The flow measurement with LDA in the mock-up of a cargo compartment proves to be a feasible method for producing data to validate CFD simulations. Qualitative evaluation of the results shows a good overall agreement between numerical and experimental results. The experimental validation indicates that the implemented CFD model is capable of reproducing the flow situation in the model mock-up.
Hunting is a potentially dangerous phenomenon related to the lateral oscillation of the wheels that impacts the rails and causes the wear of the infrastructure’s components. Therefore, the analysis and timely detection of hunting can lead to the application of corrective maintenance tasks, reducing damages, and costs and even derailments as a result. In this work, the vibration response of a finite element model of a rail with hunting-induced loads by a single wheel is analyzed in three directions: longitudinal, lateral, and vertical. The contact patch forces are calculated by means of Simpack® using the Kalker linear theory and the contact Hertz theory. The system is solved by using the Newmark-_ approach. The results of the deflection and vibration analysis, following the proposed methodology, show how the different characteristics of the loads impact the rail.
Turning maneuvers of rail vehicles involve demanding situations for the infrastructure because of the steering forces generated and the resultant lateral load transfers. Such forcing situation involves increased tangential forces that consume kinetic energy from the vehicle. While much attention has been paid in the literature to the damage in such infrastructure segments, the energy that is dissipated in these maneuvers, has not been explicitly addressed. In this paper, a specialized scale-down infrastructure is used to characterize the effect of the initial speed of the vehicle and its mass, on the magnitude of both the rail forces developed and the amount of dissipated energy during turning maneuvers. The outputs of the experiments suggest that most of the original kinetic energy is dissipated at the first portion of the turn. Also, that the magnitude of the wheel forces and the amount of dissipated energy, correlate. That is, a greater rail damage would correspond to greater energy dissipation.
Turning maneuvers of rail vehicles involve demanding situations for the infrastructure because of the steering forces generated and the resultant lateral load transfers. Such forcing situation involves increased tangential forces that consume kinetic energy from the vehicle. While much attention has been paid in the literature to the damage in such infrastructure segments, the energy that is dissipated in these maneuvers, has not been explicitly addressed. In this paper, a specialized scale-down infrastructure is used to characterize the effect of the initial speed of the vehicle and its mass, on the magnitude of both the rail forces developed and the amount of dissipated energy during turning maneuvers. The outputs of the experiments suggest that most of the original kinetic energy is dissipated at the first portion of the turn. Also, that the magnitude of the wheel forces and the amount of dissipated energy, correlate. That is, a greater rail damage would correspond to greater energy dissipation.
The efficiency and safety of railway transportation depend both on numerous factors linked to the vehicle, the infrastructure, the operator and the environment. Curved tracks are subjected to demanding situations due to elevated stress levels, as a function of the operating conditions and vehicle/infrastructure design. In such segments, steering forces are superimposed to lateral load transfers. The steering forces depend on the condition and the design of the centre plate and bogies’ suspensions design. While the friction at the centre plate provides the needed damping to mitigate the hunting vibration of the bogie in straight track segments, such yaw resistance originates high steering forces and rail damage on curved tracks. A centre plate with low friction at turns and high friction at straight track segments would thus be highly advantageous. In this paper, a centre plate design is proposed which provides a yaw-rotation resistance torque that depends on the bogie-car relative position. Two different designs are considered for that purpose, one that combines a spring-acted centring mechanism with a lower pair kinematics, while the other one involves higher kinematic pairs which should incorporate lateral damping elements. As a result of using an engineering design approach, the higher kinematic pairs-based design is recommended however, the validation of such operational principles, including the introduction of the needed damping, should be configured on the basis of experimental models.
Liquid cargo has a significant impact on the interface wheel-track interaction. The sloshing affects the track-railcar's dynamic behavior. The effect is detectable at the track level and at the vehicle. Its characterization requires the combination of different techniques:
Empirical Mode Decomposition (EMD)
Time-Frequency Maps
Sloshing occurred when significant perturbations happened in the railcar:
The railcar entered a curve
Reduction in its travel speed
A railcar with a tank is a clear example of a multibody dynamic system with a nonlinear behavior.
This paper presents the study of the impact caused by a liquid Cargo on a railway infrastructure. The dynamic behavior of a tank car corresponds to a multibody dynamic system with several degrees of freedom. This study’s data were obtained from a scale experimental fixture consisting of a track and a railcar with a tank. The track was instrumented with strain gauges and the railcar with accelerometers. The data showed non-periodic and periodic terms; therefore, the results were analyzed with the Empirical Mode Decomposition method (EMD).
It was found that the EMD identified the signal components that were related to the sloshing. These components represent the mode shapes of the original signal.
The location of the sloshing in the track was found applying spectrograms to the accelerometer data. This paper’s experimental outputs suggest that the sloshing effect is detectable at the track and in the vehicle dynamics.
100 mm of PUR-foam give satisfying results in terms of
thermal properties. The non-pressure testing methods gives reliable and repeatable results. Bending modulus of laminates does not change until the first damage occurs. After that, the bending modulus decreases by 50 % but max. stress is still higher than at room temperature.
Climate change, CO2 reduction, resource efficiency are only 3 current keywords that describe the current industrial-economic situation. In order to influence climate change effectively, the conversion of supply systems with technically usable forms of energy must succeed in the next decade. The international network founded in Baku in 2015 bundles research activities in the broad field of energy supply and energy efficiency.
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The objective of this paper is to describe and to validate a simplified pendulum-analogy model to simulate the interaction of a liquid cargo with ist carrying vehicle. The resulting testing rig consists of a rectangular container, spring supported on a two wheelset-bogie having a scale down of 1/10 with respect to a full-size equipment. The testing rig is used to validate a simple pendulum-based, simplified three degree-of-freedom mathematical model of the response of a partially filled container to lateral accelerations. The length of the pendulum is set according to validated methodologies. The resulting mathematical scheme reveals a high correlation with the experimental output, on the order of 99%, while some other performance measures, related to the peak forces and the range of variation of the wheel-rail forces, also show good concordance with the experimental results.
Scaled-down experimental facility: Can reproduce actual failures; can produce simulated data for identifying cracks in the substructure or other defects. The acceleration data can be converted into an equivalent deformation. The experimental facility can analyse dynamic loads. Equivalent force data: Facilitates the application to a health monitoring system; simplifies the development of predictive maintenance. These data is helpful in validating analytical or simulation models.
A methodology is proposed for the experimental analysis of the liquid cargo effect under combined orthogonal accelerations. To simultaneously subject the vehicle-cargo system to longitudinal and lateral accelerations, the vehicle is set obliquely on a tilt table. The experimental outputs suggest that there is a significant effect of the liquid cargo on the lateral load transfer ratio (LTR), on the order of 20%, which is attributable to the resulting shifting of the liquid cargo’s centre of gravity. That is, the peak LTR values due exclusively to sloshing were not significant, in such a way that the liquid cargo would only pose a safety risk under a steady acceleration input.
Also, the inverse of the product of the magnitude of the acceleration times the free surface length, correlates with the liquid cargo effect. That is, the magnitude of the input acceleration is not fully determinant for greater load transfers.
This paper presents a method for processing acceleration data registered on a train and determining the health condition of a subway’s substructure. The acceleration data was converted into a dynamic deformation by applying a transfer function defined using the Empirical Mode Decomposition Method.
The transfer function was constructed using data produced on an experimental rig, and it was scaled to an existing subway system. The equivalent deformation improved the analysis of the dynamic loads that affect the substructure of the subway tracks because it is considered the primary load that acts on the track and substructure. The acceleration data and the estimated deformations were analyzed with the Continues Wavelet Transform. The equivalent deformation data facilitated the application of a health monitoring system and simplified the development of predictive maintenance programs for the subway or railroad operators. This method better identified cracks in the substructure than using the acceleration data.
Die Vorhersage der Beanspruchung bei plastischem Versagen von zylindrischen Druckbehältern wird häufig mittels Finite Elemente Berechnungen durchgeführt. Die Berechnung der zulässigen Beanspruchung erfordert ein elastisch-plastisches Werkstoffmodell und die Berücksichtigung von nichtlinearen geometrischen Effekten. Das plastische Versagen verursacht eine gesamte Strukturinstabilität und kann nicht direkt aus der Finite Elemente Analyse bestimmt werden. In dem vorliegenden Beitrag wird die Beanspruchung für plastisches Versagen eines zylindrischen Druckbehälters mittels eines analytischen Verfahrens basierend auf einem linear elastischen ideal-plastischen Materialmodell bestimmt. Wenn Plastizität auftritt, wird zum einen der Werkstoff als inkompressibel und zum anderen der Tensor der plastischen Dehnungen als parallel zum Spannungsabweichungstensor angenommen. In diesem Fall kann die Spannungs-Dehnungs-Beziehung von Henkel angewendet werden, um den Druck zu berechnen, bei dem plastisches Fließen und Versagen eintritt. Die analytischen Ergebnisse werden von den Finite Elemente Berechnungen vollkommen bestätigt.
Nondestructive Testing (NDT) and fracture mechanics are two different disciplines in applied engineering science. Both areas are very important for the evaluation of the component integrity. Unfortunately the technical understanding in both disciplines is not identically, what lead to misunderstandings. In the present paper, the basic ideas about fracture mechanics and the input parameters coming from the NDT side are explained, concerning the integrity evaluation of the components. The widely used NDT methods are magnetic particle, dye penetrant, electrical eddy currents, radiography and ultrasonics. But not all of these common NDT methods can deliver parameters satisfy the fracture mechanics requirements. The first two can detect only surface-breaking or immediately sub-surface defects. Eddy current can also find defects in deeper sub-surface layers, while radiography and ultrasonics can also find embedded, remote defects. These three methods have furthermore a high potential for defect sizing and are therefore predestined to provide fracture mechanics input parameters. At the example of steam generator tube inspection the interplay of eddy current and fracture mechanics as related to tube integrity will be explained.
Pressure Vessel Fire Test
(2014)
Ermittlung explosionsfähiger Gemische beim Gefahrguttransport unter normalen Beförderungsbedingungen
(2009)
Für die Bewertung der Integrität von Tanks ist die detaillierte Kenntnis der belastungsrelevanten Parameter unabdingbar. Die Wärmeübergangszahl a ist eine derartige Größe. Die Wärmeübergangszahl bestimmt direkt die Größe der vorhandenen Beanspruchungen im Tank. Insofern sollte die Wärmeübergangszahl bekannt sein. Aus diesem Grund wurden experimentelle Untersuchungen durchgeführt. Für einen sich im Feuer befindlichen Tank ergibt sich die Wärmeübergangszahl zu 50 W/m2K. Auf dieser Basis konnten die bereits durchgeführten experimentellen Untersuchungen mithilfe der Methode der finiten Elemente nachgerechnet werden. Die dabei erzielten Ergebnisse sind infolge der getroffenen modelltechnischen sowie thermodynamischen Vereinfachungen als zufriedenstellend zu bezeichnen. In einem nächsten Schritt wird an einer verbesserten Modellierung sowie thermodynamischen Beschreibung der Verhältnisse im Tank gearbeitet.
In einem von der BAM Bundesanstalt für Materialforschung und -prüfung durchgeführten Forschungsvorhaben wurde untersucht, inwieweit bei Gefahrguttanks im Brandfall ein 'BLEVE', d. h. ein Versagen der Umschließung mit anschließender Freisetzung der Flüssigkeit bzw. des verflüssigten Gases, verzögert bzw. verhindert werden kann.
Pressurisation of full-containment pressure vessels in fire is known to be driven by thermal stratification. The predominant mode of heat transfer to the contents (convection from the shell to the liquid phase) results in formation of „hot“ boundary layers. Sub-cooled boiling may also be present. The warm layer rises to the surface through buoyancy and bubble flow, increasing the surface of the liquid above that of the bulk temperature, and hence driving a pressure rise.
For reliable prediction of the complex effects governing vessel pressurization a three-dimensional numerical model is required. Work is being undertaken on such a model by other institutions in cooperation with this project.
A new tank design for Hazmat
(2016)
Initial studies have shown pre-deformed honeycomb structure
pressure vessels to have comparable burst pressure to straight steel vessels.
It was shown that honeycomp structured tanks have a higher energy absorption than straight steel tanks.
Future studies will investigate optimization of the deformed plate, to determine if increased payloads or a reduced wall thickness can be achieved.
The outputs from a simplified mathematical designed to simulate the liquid cargo-vehicle interaction during an emergency braking maneuver, have been compared with full scale data regarding the sloshing pressure on one of the vehicle chambers. While the specific dimensions and fill level of the fluid within the chamber in the full scale testing, have been considered for the simulation model, the vehicle has been simplified to a straight truck instead of an articulated truck. Nevertheless, the pressure within the chamber is realistically modelled, concerning the maximum and minimum pressures attained, with differences lower than 10% between the simulation and the experimental data. Consequently, these results suggest that the articulation pertaining to the articulated vehicle, does not affect in a significant manner the maximum and minimum values of the pressure within the chamber. A nonlinear model for the suspension, however, could improve the model performance. On the other hand, simulation results suggest that the effect of sloshing could cause a loss of braking efficiency on the order of 7%, when such performance is measured in terms of the stopping time.
Simplified cargo-vehicle interaction: linear pendulum, rigid multibody linear dynamics, straight, instead of articulated vehicle.
Realistic results about the pressure developed on the sensor, with differences lower than 10% between the simulation and the experimental data.
Sloshing could affect the braking efficiency in 7%, approximately, corresponds with other sources.
The arrangement of the measuring sensors allowed the
capture of air flow induced temperatures and material
temperatures on various points of the cylinder body. Four
significant temperature levels could be observed: Inside the cylinder (far from the wall, close to the wall), inside the aluminium liner and outer surface. Figure 5 shows the temperature distribution after a regular filling process with a filling time of ten minutes. The temperature sensors T1 - T9 are marked with different colors. The corresponding measurement points are shown in Figure 4. Due to the high thermal conductivity of the aluminum liner the induced temperature peaks are quickly derived. A flow-induced exceeding of the maximum approval temperature is not expected. Regarding the safety assessement the results show that the pressure and temperature profilesmustbe taken into account.
The US Department of Transportation, Federal Railroad Administration (FRA) current regulations for rail tank cars in the United States stipulate that, for certain hazardous materials, tank cars shall have a thermal protection system capable of preventing rupture of the tank for 100 minutes when exposed to an engulfing fire with a blackbody equivalent flame temperature of 871 °C (+/- 56°C), and that tanks shall have a pressure relief device set at an appropriate level (depending on the type of tank car and contents). Pressure relief devices are a source of non-accident releases, and hence may cause serious incidents when tanks are transporting hazardous materials. Industry in North America would therefore benefit from removal of pressure relief devices on tanks transporting certain hazardous materials. Such an approach is known as full Containment, and is standard practice in Europe. In 2014 the FRA commissioned an experimental study to investigate the ability of a specific design of rail tank to resist rupture without incorporating a pressure release valve. As a precursor to tests on tanks there was a need to develop and characterise a simulated pool fire capable of reliably exposing large-scale tanks to repeatable, uniform conditions. This paper describes such a fire test setup, developed using a burner array system fuelled by liquid propane and designed to produce luminous, low velocity flames representative of those found in large hydrocarbon pool fires. The experimental set-up is described, along with the Instrumentation (directional flame thermometers, infra-red camera, and thermally massive calorimeter) and methodology used to characterise the fire. Comparisons are made against previous fire tests on vessels to assess the suitability of the experimental set-up for future vessel testing.
Limit load analysis is a well known method to calculate the allowable design pressure of container components. A limit load of a pressurized container is achieved, when the stress of a wall and the flow stress are equal. In the following paper the transferability of limit load analysis from small scale tank containers up to large scale containers (railway tank) are investigated. Finite element calculations are carried out and compared with experimental results. It can be concluded that the limit load analysis works very well. Furthermore, the yield strength of the material should be used as flow stress.
The prediction of the plastic collapse load of cylindrical pressure vessels is very often made by using expensive Finite Element Computations. The calculation of the collapse load requires an elastic-plastic material model and the consideration of non-linear geometry effects. The plastic collapse load causes overalls structural instability and cannot be determined directly from a finite element analysis. The ASME (2007) code recommends that the collapse load should be the load for which the numerical solution does not converge. This load can be only determined approximately if a expensive nonlinear analysis consisting of a very large number of sub steps is done. The last load sub step leading to a convergent solution will be taken as the critical load for the structure. In the instability regime no standard finite element solution can be found because of the lack of convergence of the numerical procedure. Other methods for the calculation of the allowable pressure proposed by the ASME code are the elastic stress analysis and the limit load analysis. In the present paper the plastic collapse load for a cylindrical pressure vessel is determined by an analytical method based on a linear elastic perfectly plastic material model. When plasticity occurs the material is considered as incompressible and the tensor of plastic strains is parallel to the stress deviator tensor. In that case the finite stress-strain relationships of Henkel can be used for calculating the pressure for which plastic flow occurs at the inside of the vessel wall or in the case of full plasticity in the wall. The analytical results are fully confirmed by finite element predictions both for axisymmetric and high costs three dimensional models. The analytical model can be used for fast predictions of the allowable load for the design of a large variety of pressure vessels under safety considerations. The accuracy of the predicted collapse load largely depends on the quality of the temperature dependent wall material data used both in the analytical and numerical calculations.
The vessel wall response shows a good agreement between the numerical predictions of and experimental data using the limit load approach. Further work is continuing to understand the thermohydraulic response and the boundary conditions for material modelling. As shown in figure 2 there was one BLEVE of a bare tank containing a PRV, highlighting the risk of serious consequences if models are inaccurate. The behavior of partly coated tanks were similar to the bare tank.
Parameter study for CFD in the bottle – grid resolution plays an important role on the temperature at the specific positions, 2D axi-symetrical calculation is a sufficient solution strategy in regards to the examined particular Problem. The intensity of filling process can be controlled by pressure “User defined function” provided by experiments. Numerical simulation demonstrated feasibility to predict temperature progress during the filling process successfully validated by experiments. The turbulent model k-w SST is the best strategy for the turbulent property calculations. The most intensive turbulent kinetic energy appeared in the middle region of the pressure bottle, the impact of the eddy viscosity on the wall was mostly in the wall region.
Die BAM – Bundesanstalt für Materialforschung und -prüfung führt schon seit vielen Jahren auf zwei Brand- prüfständen Brandprüfungen z.B. an Transport- und Lagerbehältern für radioaktive Stoffe oder zur Prüfung von Brandschutzbeschichtungen durch. Als Brandmedium wird auf diesen Prüfständen Flüssiggas (Propan- Butan-Gemisch C) eingesetzt, mit dem die Prüfobjekte simulierten Unfallfeuern ausgesetzt werden. Mit dem neuen Jetfire – Prüfstand der BAM können seit Anfang 2018 diverse Belastungsszenarien nach den Anforde- rungen der ISO22899-1:2007 [1] simuliert werden.
A testing rig for the measurement of the dynamic loads on the rails due to cargo sloshing,has been proposedin this paper. The system represents a scale-down approach that simulates astraightening maneuver of the railway car after negotiating a turn. As part of the experimental effort, a mathematical model was developed that, oncevalidated, will provide more insights about the potential effect of many other cardesign factors, on the level of stress developed in the raildue to the sloshing cargo.A fundamental output from the testing, will be the objective comparison between the railloads due toa sloshing and a non-sloshing cargo, together with a validated model that wouldallow parametric studies in relation withthe potential effect,of several track and carproperties,on the magnitude of the sloshing forces on the rail.
Wasserdruckprüfung kann entfallen: Schutzziel definieren, Qualitätssichernde Maßnahmen während der Herstellung, Nachweise der vorhandenen Qualität muss stetig erfolgen mittels: Betriebsüberwachung, zfP Bewertung des Standes der Technik: Zustandsorientierte Instandhaltung/Inspektion, Reduzierung von Ausfallzeiten durch optimierten Betrieb
Effective assessment and management of railway infrastructure for competitiveness and sustainability
(2018)
In this chapter the challenges facing railways have been illustrated through the description of two important events occurring in different geographical areas. While the explosion in Quebec, Canada, points out the importance of taking away the transportation infrastructure from highly populated areas; the disruption of the European railway network in Rastatt, Germany, describes the importance of designing alternative routes to critical railway segments, together with the need to have contingency plans to face extraordinary situations regarding the connectivity in a given transport network.
Future research efforts are recognized in relation with the railway car – track interaction, as the dynamic loads derived from such interaction could be reducing the life of such infrastructure. It is particularly important for infrastructures dedicated to the transportation of liquid hazardous substances.
Wheel forces generate stresses in the rail as a function of several vehicle and infrastructure characteristics and operating conditions. The different components of the wheel forces develop strains in the rail which contain an elastic and hysteretic (irreversible) components. The irreversible deformations of the rail would be associated with locomotive energy losses. In this paper, a testing facility is proposed to indirectly characterize the level of stresses in the rail, in terms of the energy that is lost during tuming maneuvers. Different potentially influential factors are considered, including the friction at the Center plate, the wheelbase length, the distance between bogies and the radius of the curved track. The change
in the potential energy during a U-turn displacement is measured. In this respect, an experimental model under this operating principle, aimed at validating such a principle of Operation, reveals a significant effect of the friction at the center plate on the energy lost during turning maneuvers, and consequently, on the level of stresses in the rail.
Exposure of pressure vessels to fire can result in catastrophic explosion and escalation of accidents. The safe transportation of cargo in pressure vessels therefore requires knowledge of what will happen to the cargo in the event of a vehicle derailment or rollover resulting in fire exposure. The chapter presents an overview of selected testing and modelling work undertaken to understand the thermohydraulic processes within a vessel that drive pressurization during fire. A series of experiments highlighting the importance of adequate design and selection of protection systems are summarized. It is concluded that pressure relief alone is typically insufficient to prevent vessel rupture, but the combination of relief and thermal coatings can be effective.
An overview of test standards and regulations relevant to the fire testing of pressure vessels
(2021)
Fire exposure of storage and transportation vessels of hazardous materials (including pressure liquefied gases) can result in BLEVEs and other high-consequence incidents with large societal and economic impacts. To reduce risk most countries have numerous regulations, codes of practice and guidance notes covering the design, operation and maintenance of vessels and thermal protection systems. Yet despite such regulations there remains no internationally accepted fire test procedure for pressure vessel and accompanying thermal protection systems that is capable of meeting a range of regulatory requirements. This paper considers some of the regulations in place in the western world and considers the origin of these based on large and medium-scale testing conducted to date. It examines conditions found in these tests to propose a set of recommendations on which to base a standard method of test. These recommendations are proposed as being representative of a credible large pool fire scenario that may occur.
In spite that transport activities do not represent the biggest contributor of pollutants emissions, their reduction has been a priority as some other externalities are associated to such emissions and to the transport itself. A crucial element to characterize the behavior of the vehicles against the environment are the losses that such vehicles exhibit in a passive way, that is, without any involvement of power conditions. The energy loses due to the rolling, the drag and to the friction in mechanical components, have been assessed so far in terms of the stopping acceleration when the vehicle idles on a ramp. However, such a testing procedure produces some uncertainties due to the dynamic conditions that are considered. To avoid such critical limitations, in this paper a testing procedure and facility are proposed, which are based on static conditions of the vehicle at the initiation and at the ending of the test, which are assumed to provide a better reliability to the testing. Some preliminary theoretical analysis should be made in order to validate the operational principles proposed herein for such testing facility.
Different approaches have been attempted so far to reduce fuel consumption and linked pollutants, including vehicle equipment and design, with rational driving style being recognized as a potential source of fuel savings. However, no specific methodology had been suggested so far to assess fuel economy of driving other than the fuel consumed itself. In this paper, the Standard deviation of driving acceleration has been found to be directly associated to fuel consumption, so that the less dispersion of the driving acceleration, produces the lower fuel consumptions and emissions. Such metric could be thus used to assess driving style.
Turning maneuvers originate higher forces exerted on the rail and the loss of locomotive energy, at a rate that is function of several parameters that influence the magnitude of the developed horizontal wheel-rail forces, including the friction at the centre plate and the bogie´s yaw stiffness. However, such a friction at the contact surfaces of the centre plate is needed to mitigate the Hunting phenomenon when the train moves on straight track segments. In this paper, a self-centering centre plate is proposed, consisting of a lubricated centre plate, equipped with a spring- and damper-based self-centering mechanism. Simulation results of the proposed mechanism suggest that the energy performance in turns of a train car equipped with such self-centering centre plate is comparatively better, as the peak friction forces linked to the dry friction at the contact surfaces of current centre plate designs, are avoided. The assessment of the hunting performance of the proposed device in straight track segments is proposed as the continuation of this work.
A facility is proposed in this paper to apply a selective carburizing process to the lateral faces of a railways´ head, aiming to increase its carbon content and to decrease the friction coefficient in case that the flange of the railway car wheel gets in contact with the rail during turning. Such a treatment would reduce the energy that is lost during the turning maneuvers performed by the vehicle, further improving the energy efficiency of the railway car. The facility consists of a furnace, which should be set next to the rails´ hot-rolling facility, in order to use the available enthalpy. The proposed furnace is equipped with what is necessary to avoid the decarbonization of the remaining rail material, based upon batteries of oxy-acetylene burners that are installed at the bottom of the furnace, on the opposite side to the carburizing surface. An experimental facility is necessary to validate the operational principles for the equipment proposed in this paper. On the other hand, a study should also be carried out to assess the effect of any rail welding process on the carburized surfaces.
Gefahrguttanks werden primär gegen betriebliche Belastungen dimensioniert. Unfallbelastungen spielen hierbei keine Rolle. In der Vergangenheit gab es immer wieder einige katastrophale Unfälle, die nicht nur materielle Schäden zur Folge hatten sondern bei denen auch Todesopfer zu beklagen waren. Zur Ermittlung möglicher Sicherheitsreserven werden Untersuchungen zum Abtrag auslegungsüberschreitender Belastungen durchgeführt. Mit dem Grenzlasttragverfahren steht ein leistungsfähiges Analysewerkzeug zur Verfügung, mit dem nichtlineare Beanspruchungsszenarien bewertet werden können. Der Vergleich der numerischen mit den experimentellen Ergebnissen zeigt dies eindeutig.
Gefahrguttanks
(2016)
Given the frequent incidences of Non-Accident Releases (NARs) of hazardous materials from tank cars, there in an increasing interest in transporting hazardous materials in total containment conditions (i.e., no pressure relief devices). However, the ability of tank cars to meet thermal protection requirements provided in the Code of Federal Regulations under conditions of total containment has not been established. Also, the modeling tool commonly used by industry to evaluate thermal protection, AFFTAC, has not been validated under these conditions. The intent of this effort was to evaluate through a series of third-scale fire tests, the ability of tank cars to meet the thermal protection requirements under total containment conditions, and also, to validate AFFTAC for such conditions.
This paper describes the test design and planning effort associated with this research, including the design and evaluation of a fire test setup to simulate a credible, fully engulfing, pool fire that is consistent and repeatable, and the design and hydro-static testing of a third-scale tank specimen. The fire design includes controls on the spatial distribution and temperature variation of the flame temperature, the heat flux, and the radiative balance, to best reflect large liquid hydrocarbon pool fire conditions that may be experienced during derailment scenarios.
Using plastic jerrycans or plastic containers, dangerous goods are transported as air freight in commercial aircrafts. Liquids or gases can escape by leakage or permeation effects from these plastic containers. The German Federal Institute for Materials Research and Testing (BAM) conducted prior research which showed that the lower explosion limit can be reached when transporting dangerous goods in sea-freight containers under normal transportation situations. The presented study is motivated based on these findings. The research objective of this study is to analyze the transportation situation of dangerous goods in cargo compartments of commercial airplanes. The scope of this paper is to present the experimental method used for validating a numerical model for CFD (Computational Fluid Dynamics) simulations and to present some simulation results of the mass transport of dangerous goods in the cargo compartment.
The velocity profiles and the mass transport is calculated using numerical simulations and measured by Laser-Doppler-Anemometry (LDA) experiments. The mock-up is a generic model of a wide-body aircraft lower deck cargo compartment in a 1: 10 scale. Geometry, air exchange rates and inlet as well as outlet flow conditions in the cargo compartment are modeled using realistic boundary conditions. The commercial CFD (Computational Fluid Dynamics) code ANSYS CFX 14 is used for numerical flow simulations applying RANS (Reynolds-Averaged-Navier-Stokes) equations and turbulence models. The turbulence models studied are the renormalization group k-e-model (RNG), the BSL-Reynolds-Stress model (BSL) and the SST-k-co-model by Menter (SST).
The flow measurement with LDA in the mock-up of a cargo compartment proves to be a feasible method for producing data to validate CFD simulations. Qualitative evaluation of the results shows a good overall agreement between numerical and experimental results. The experimental validation indicates that the implemented CFD model is capable of reproducing the flow situation in the model mock-up
This paper describes the testing methods used to determine the thermal properties of insulation materials and mechanical properties of materials used for the load-bearing structure for pressure tanks (up to 4 bar, relative) and cryogenic liquids (LNG, −166 °C to -157 °C at atmospheric pressure). Goal is to design a transportation tank that does not exceed 4 bars (relative) within 10 h, starting at atmospheric pressure. PUR-foam is a suitable material for the insulation. A 12,5 l small scale tank prototype reached 4 bar (relative) within 87 minutes, which is, regarding the influence of the size, a satisfying result. The mechanical properties change significantly at cryogenic temperatures. The bending modulus is similar at first, but decreases at a certain point by appr. 50 %. However, the maximum stress is much higher and could not be reached within this testing setup.
A simplified formulation is proposed in this paper to assess the proximity of the earthquake-related Perturbation frequencies to the natural sloshing frequencies of the liquid contained in vertical cylindrical tanks. The methodology is based upon an existing gravity-waves approach, which was developed for rectangular cross-section reservoirs, and is extended in this paper to analyze circular cross-section tanks.
The experimental outputs of this paper show that the existing methodology correlates at 100% with experimental data in the case of rectangular containers; while the corresponding average error in the case of a conical container and a cylindrical container is 7% and 9.1 %, respectively. The full diameter of the cross section was considered. The use of sovalidated methodology to full scale tanks, suggests that cylindrical vertical tanks with a capacity lower than 700 m3, could be exposed to a resonance excitation when subjected to
earthquake motions, regardless of the fill level.
Tanks with capacity larger than 700 m3, could be exposed to a resonance excitation when subjected to earthquake motions, regardless of the fill level. Further studies to assess the dynamic forces linked to such resonance and close-to-resonance situations, in a context of a standard overloading situation due to sloshing forces.
To reduce the emission of carbondyoxide (CO2) of combustion engines, liquefied natural gas (LNG) is used as an alternative fuel. LNG is transported via truck, ship or railway for long distances. Double walled stainless steel tanks are used for transportation, which are heavy and expensive. The vacuum insulation between the two walled structure ensures that the LNG stays liquid over the transportation time (boiling point of LNG: -162 ◦C). This causes a high temperature difference between the transported good and the ambient air.
A simplified tank construction is used to reduce the weight and price of the tank. Instead of stainless steel, glass fiber reinforced plastic (GFRP) is used. The design is changed to a single walled construction with a solid insulation material outside on the GFRP structure.
Goal of this work is the characterization of a suitable insulation material and configuration as well as the analysis of the mechanical properties of GFRP under cryogenic conditions. Several experiments are carried out. Numerical models of these experiments can then be used for parameter studies.
The efficiency and safety of railway transportation depends on many factors and operating conditions, associated to the vehicle, the infrastructure, the operator and the environment. From the vehicle-infrastracture perspective, some influential factors include the dynamics of the vehicle and infrastructure interaction when the vehicle operates on curved tracks. Düring such changes of direction, the vehicle dynamically responds to the lateral perturbation, producing a lateral load transfer that represents an increase of the wheel forces on one side of the track, as a function of the train operating conditions and track design, including track's geometry and over-elevation, and vehicle's operating speed as well as its inertial properties and dimensions. In this context, the lateral load transfer superimposes to tangential steering forces, which are developed when the vehicle enters the curved track, and stabilize once a steady state is attained if the vehicle travels along a constant radius track at constant speed. The magnitude of such tangential forces depends on a variety of factors, including the yaw stiffness of the bogie, and the friction at the centre plate. While the friction at the
centre plate generates higher tangential forces on the track and a consequential greater rail wearing and lose of locomotive energy, such friction is also crucial to avoid the hunting phenomenon when the vehicle travels along tangents.
In this paper, a mechanically active centre plate is proposed, which increases the friction torque at the centre plate when the vehicle travels along tangents, and reduces such a friction torque when the vehicle negotiates curved portions of the track. Such conceptual design includes the principles of Operation and a needed preliminary
experimental model to assess the potential benefits as well as the feasibility of such equipment.
Greenhouse gas emissions caused by human activities remain one of the most important subjects of international discussions. The routine gas flaring has been estimated to be responsible for as much as 1% of global carbon dioxide emission per year. Gas flaring analysis is one of the key-interest subjects in remote sensing community. Some of the existing publications use remote sensing techniques with satellite imagery to derive information about flame temperature and further about to estimate the volume of the flared gas. The often missing element is an in-situ measurement analysis of gas flames, combining signals recorded by a camera on-ground and data on flared gas volume, temperature and gas type. In order to address this problem, an experiment was conducted, in which the gas flame was recorded by thermal cameras on-ground, simultaneously to an aerial survey and the gas flow was measured at the same time on-ground. The measurement setup was designed in cooperation between Institute of Optical Sensor Systems of German Aerospace Center (DLR) and German Federal Institute for Materials Research and Testing (BAM). Cameras recording in thermal and mid-wave IR wavelengths were used to record the burning gas on-ground and from the aerial survey. All the measurements have been compared and statistically analysed with respect to the recorded temperature. The purpose of the examination was to describe the signal changes in thermal imagery with respect to changes in energy, emitted by the burning process. This approach will allow for later calculation of the amount of energy in form of thermal radiation sent from the flame to the satellite.
Liquefied propane gas (LPG) tanks in a fully engulfing accidental fire experience a fast increase in internal pressure. The result is often a Boiling Liquid Expanding Vapor Explosion (BLEVE) that can result in a large fireball and flying debris over a radius of more than 100 meters.
In the last 30 years BAM has carried out more than 30 real scale fire tests on propane storage vessels across three test sites. The primary research goal was to identify systems that can delay or prevent a BLEVE. Early studies started with water deluge systems, and have since moved on to consider alternative protection systems.
It has been shown that an unprotected vessel fails within 10 minutes or less. Tests with different oil and propane fueled fires have given an overview on possible real accidents involving full-engulfing scenarios. LPG tanks of various sizes (2.7 m³, 3.6 m³, 4.8 m³, 6.7 m³) were used with different filling levels. Numerous protection systems, ranging from active systems like water systems to passive thick- and thin-film layers. Also, the degree of thickness of these layers was variated. Pressure relief valves (PRV) have also been investigated, both alone and in combination with protection systems.
This paper gives an overview of the work performed by BAM in the field of BLEVE prevention of protecting system since the last 30 years. It has been shown that e.g. with a full applied coating degree on the tank with and without PRV can be reached an exposition in a test fire scenario a duration of more than 60min. For partly coated tanks with and without PRV the duration time is like an unprotected vessel. Furthermore, it could be shown that the active water system also protects with technically correct design.
Braking-in-a-turn maneuvers represent a critical operational condition for any vehicle, due to the associated longitudinal and lateral perturbations to which it is subjected, which maximize the load transfer among the different wheels, and result in vehicle´s poor lateral stability and deficient braking performance.
In this paper, a suspended vehicle supporting a partially filled 10 litter-capacity container, is set on a tilt table at oblique angles, in order to simulate a braking-in-a-turn maneuver. The measurements are assessed in the time and frequency domains, on the basis of the lateral load transfer ratio and the infrastructure fatigue damage. The outputs from the experiment show that the Minimum fill level (one-quarter), generates the larger lateral load transfer (0.45). Such fill level also causes the greatest ratios for the alternate stress over the mean stress on the infrastructure. The spectral analysis reveals the dominance of one of the sloshing frequencies during such combined perturbation condition.
Vehicle’s components damage
(2020)
The failure of vehicle’s suspension components has contributed to road crashes, while their defective operation can deteriorate the fuel efficiency of the vehicles. In this context, and when compared with solid cargo transporters, the road tankers would tend to produce larger roll forces during turning, as the curved shape of the liquid cargo container, shifts upwards the centre of gravity of the cargo. With reference to a rectangular cargo container representing the solid cargo situation, the increase in the position due to elliptical and circular tank shapes, can attain a value of 17% (100% fill, circular tank). In this study, experimental results comparing the lateral load transfer due to solid and liquid cargoes, indicate that the average force increase on the vehicle’s load-receiver side due to a liquid cargo, is 4.3%. To analyse the fullscale situation of both situations, that is, the higher position of the centre of gravity and the shifting of the liquid cargo, a simplified model is developed. The outputs from such a model when subjected to realistic operating conditions (speed
and turning radius), suggest that the higher position of the centre of gravity due to using a non-rectangular cargo container generates an average force increase of 4.9% on the side receiving the load transfer. The incorporation of the effect of the liquid cargo, through the simple pendulum analogy, suggests that such an average increases to 6.76%, with a maximum of 8.35% in the case of the elliptical tank at 75% fill level. It is found that the average liquid cargo effect is 5.44%, which should be compared with the 4.3% of the experiments. Road tankers components would thus have a relatively shorter load cycle life than those of the solid cargo trucks.
Several geometrical analytical tools can be used for assessing the potential benefits of any alternative tank shape. The quasistatic evaluation of the cargo-vehicle behavior represents a fast way to objectively determine the roll stability benefits of any potentially new tank shape. In this paper, the geometrical, quasistatic rollover performance of a convex bottom tank shape is compared with that of standard tank shapes, finding that in spite of the lower position of the cargo´s center of gravity in such a tank shape for the un-perturbed condition, it has the same performance as the elliptical tank shape when subjected to Steady lateral acceleration. That as a result of the large cargo´s lateral displacement. Consequently, the combination of a lower center of gravity for the cargo when it is not perturbed, and a Minimum lateral shift due to lateral accelerations inputs, define the conditions for an ideal tank shape.
Regardless of the mode of transportation, directional changes generate greater forces on the infrastructure as a result of the lateral load transfer and of the respective steering forces in the vehicles. In the case of Railway transportation, a concentrated damage occurs in the rail at the initiation of the turning maneuver, whose magnitude depends on the bogie´s yaw stiffness and on the level of friction at its centre plate. To mitigate such rail-damaging effects, some new designs have been proposed and used for the bogies´ wheelset. However, no new designs for the centre plate have been used. In this paper, a review of the causality for the forces arising during Railway Vehicle's turn negotiations, is presented, including the description of a modeling framework to analyze the influential Parameters for determining the magnitude of such forces.
The transportation of liquids involves several situations derived from the curved shape of the cargo containers, including a comparatively high center of gravity, which negatively shifts when the container is partially loaded, and the vehicle is subjected to steering or braking accelerations. Aiming at reducing these effects several experimental approaches have been applied, involving different tank shapes and the use of baffles, tested under laboratory or field conditions, at full scale or at a down-scale. However, the scope of such approaches has been limited, mainly because the potential effect of other components of the vehicle on the road tanker behavior, has been neglected. In this paper, a critical review is presented of the experimental approaches considered so far, identifying specific experimental needs to improve the performance of the vehicles, from both the road safety and the environmental perspective.
Externalities of the road transportation are multidimensional in nature and involve the road-vehicle interaction under different environmental conditions. Estimating the pavement and vehicle damage potentials as a function of the condition sunder which such interaction takes place, is important to avoid accelerated or catastrophic damages in these systems. Such an assessing is crucial from the perspective of pricing the effects of the vehicle on the infrastructure and vice versa. The existing models for pricing such interaction, critically depends on gross average statistical models. In this paper, it is proposed a deterministic approach to realize such an assessment, based upon validated approaches for the pavement damage. The simulation scheme considers different degrees-of-freedom vehicle models, and a discrete asphalt pavement, that make possible the simulation of massive traffic situations on realistic road lengths.
A testing methodology has been proposed in this paper, to compare the load transfer derived from solid and liquid cargoes when the carrying vehicle is subjected to a lateral acceleration in a tilt table. Besides the type of cargo, the other factors
(a) One-quarter fill level
(b) One-half fill level
(c) Three-quarter fill level
(d) Fast input
considered are the fill level and the rate at which the considered are the fill level and the rate at which the acceleration input is acceleration input is exerted on the vehicleexerted on the vehicle. The acceleration The acceleration input can represent the entering of the carrying vehicle into a input can represent the entering of the carrying vehicle into a curved portion curved portion of of aa road.
The testing device integrates the needed components to measure the fourmeasure the four--wheel loads of the wheel loads of the carrying vehicle, while carrying vehicle, while providing different times to attain providing different times to attain aa 10°10° angle angle for the tilt table. for the tilt table.
The performance measure selected is significant to assess the rollover trend of a vehicle, on the basis of the wheel loads at both sides of the vehicle. both sides of the vehicle.
The outputs from the experiments suggest that the sloshing suggest that the sloshing cargo transfercargo transferss the greater loads, the greater loads, regardless of the fill level and regardless of the fill level and acceleration rate inputacceleration rate input, as a result , as a result of the shifting of the center of of the shifting of the center of gravitygravity of the liquidof the liquid, and of of the the dynamic vibration at the end of dynamic vibration at the end of the perturbation input. In this respect, while the solid cargo the perturbation input. In this respect, while the solid cargo exhibits an initial peak and decay, the exhibits an initial peak and decay, the sloshing cargo exhibits sloshing cargo exhibits several oscillations of the saseveral oscillations of the same magnitude, which is attributed me magnitude, which is attributed to the to the liquid inertia and liquid inertia and to the to the reflection of the surface waves. reflection of the surface waves.
A further analysis could supplement this research, to assess supplement this research, to assess the effect of some other factors on the dynamic the effect of some other factors on the dynamic behavior of the behavior of the liquid cargoliquid cargo-vehicle system. Fvehicle system. For example, to analyze the effect or example, to analyze the effect of longitudinal baffles, and to validate theoretical models.of longitudinal baffles, and to validate theoretical models.