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Organisationseinheit der BAM
- 2 Prozess- und Anlagensicherheit (5)
- 2.1 Sicherheit von Energieträgern (3)
- 2.0 Abteilungsleitung und andere (2)
- 7 Bauwerkssicherheit (2)
- 8 Zerstörungsfreie Prüfung (2)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (2)
- 2.2 Prozesssimulation (1)
- 3 Gefahrgutumschließungen; Energiespeicher (1)
- 3.0 Abteilungsleitung und andere (1)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (1)
The vibrations of soil and foundations are demonstrated for different types of loading. Train-induced ground vibrations are studied in a measurement campaign where a test train has run with regularly varied speeds. The measured train-induced soil vibration at 2 to 100 m distance from the track is compared with the wave propagation due to hammer excitation and with the theoretical wave field. The strong influence of the soil and the train speed on the amplitudes and frequencies of the vibration has been analysed for passages of the locomotive and the carriages. - The generation of ground vibration by strong explosions has been studied on a large testing area with sandy soil. The propagating waves were measured in a regular grid of measuring points in 10 to 1000 m. Therefore, the dominance of certain waves at certain distances and the changes of compressional waves and Rayleigh waves could clearly be observed. The results are compared with impulse hammer measurements in the range of 5 to 50 m. - A drop test facility has been built on the testing area of the Federal Institute of Materials Research and Testing (BAM). Heavy masses (containers) of up to 200 t can be dropped from 10 m height on a big reinforced concrete foundation. The foundation was instrumented by accelerometers, strain gauges and pressure cells to give information about the loading condition and by geophones to measure the vibration of the surrounding soil and building. Both excitation processes, the release of the mass and the impact, produce high vibration amplitudes. On a smaller drop foundation, the influence of the drop height and the target stiffness has been studied more systematically.
Die Mikroverfahrenstechnik (typische innere Abmessungen der Apparaturen < 1000 pin) erfährt zunehmend Interesse für industrielle Anwendungen. Grund hierfür sind verschiedene Vorteile gegenüber konventionellen chemischen.
Reaktoren wie ein erhöhter Wärme- und Stofftransport und größere spezifische Phasengrenzen. Hierdurch können im Zuge einer Prozessintensivierung höhere Raum-Zeil-Ausbeuten und Selektivitäten und darüber hinaus eine sicherere Prozessführung erreicht werden. Dies trifft vor allem dann zu, wenn als Oxidationsmittel reiner Sauerstoff, Distickstoffmonoxid (Lachgas) oder ähnliche Substanzen mit hohem Oxidationspotential eingesetzt werden. Vielfach wird angenommen, dass Mikroreaktoren inhärent sicher gegenüber Deflagrations- und Detonationsvorgängen sind. Durchmesser der Reaktionskanäle von 0,5 nun und kleiner lassen Flammendurchschläge zumindest bei Stoffen der Explosionsgruppen I1A und TIB für Gemische mit Luft als Oxidationsmittel und Umgebungsbedingungen (ca. 20 °C, ca. 1.013 mbar) als ausgeschlossen erscheinen. Für die in der Mikroverfahrenstechnik bevorzugten Reaktionsbedingungen wie erhöhter Druck, erhöhte Temperatur und vor allem Oxidationsmittel mit erhöhtem
Oxidalionspotential gilt dies jedoch nicht.
More than 400 iron hydrogen storage containers (also called bottles or cylinders exploded on the air strip Berlin-Tempelhof on May 25, 1894, leaving immense destruction. The Royal Prussian Materials Testing Institute was requested to investigate the material properties and to furnish an expertise, how an increased safety of such cylinders might be achieved for the future under protection of the interests of the air ship service, as for instance by improvement of delivery specifications or respective material inspections.
The studies conducted personally by the director Prof. Adolf Martens and his deputy Prof. M. Rudeloff represent one of the first comprehensive failure case investigations in history and initiated BAMs long tradition in failure analysis. Martens and his colleague elaborated quite detailed specimen plans and investigated original failure parts with a special emphasis on conspicuous fracture appearance, but also made comparison experiments with hardened as well as annealed samples. Experienced investigators might identify some first routines how to conduct failure analyses and the importance of Adolf Martens as a pioneer in this field becomes evident.
Martens publications about the original expertise Martens, 1896 [1] and [2] include detailed descriptions about the experimental procedures and specimen preparation. Also, quite modern materials testing technologies and machines have been utilized, as for instance light microscopy as well as the tensile testing machines developed by Werder and Pohlmeyer. As special features developed by Martens, precision strain measurements have been applied during respective tensile tests and the so-called micro-photographic apparatus has been adopted to produce photos of the investigated microstructures. Additionally, the publications contain at that time very valuable advices regarding appropriate materials selection for gas storage cylinders.
The present contribution provides a nearly complete and as exact as possible translation of the original report Martens, 1896 [1] written in Old German language. Only little changes have been made in the text for a better understanding.
The explosion of hydrogen gas storage cylinders on May 25, 1894, represents one of the most spectacular failure cases during the late industrialization period in Germany. With respect to modern applications to hydrogen storage as energy carrier, it has several times been referred to as precedent failure case for the whole industrial sector. The detailed investigation reports by Martens have thus gained interest in the last years, but also, because the publications in 1896 about his expertise already provided in September 1894 document one of the first and most comprehensive investigations which can be regarded as a nucleus for modern failure analysis.
After summarizing the newspaper reports in the introduction, the present contribution provides a review of Martens' reports targeted at the development of failure analyses and materials testing procedures as well as potential failure origins.
Preventing the explosion of acetylene cylinders involved in fire with help of numerical modeling
(2012)
The current paper describes a mathematical model, which was developed to simulate the heat transfer in acetylene cylinders during exposure to a fire. The cases of a direct engulfment of the cylinder in the flames and of exposure to a distant fire were considered. Furthermore, the model was also applied to the prediction of the heat transfer during the cooling with water of heated acetylene cylinders, in order to assess the effectiveness of this procedure as a measure to prevent the burst of the cylinder. To provide data for the definition and validation of the model a total of 13 bonfire tests with 8.9-, 10- and 50-dm³-cylinders were performed, where pressure and temperature measurements in the samples were performed. During 5 experiments the fire was extinguished before the expected cylinder burst and a cooling with water was applied. In the paper a short description of the experimental set-up and of the test results is given. Finally, a comparison with the model predictions is provided, showing reasonable agreement.
Acetylene pressure cylinders are widely used in the industrial sector for welding, flame cutting, or heating.
Sometimes during work, not only with acetylene cylinders, fires occur and in this case the risk of destruction increases and the behavior of such an exposed cylinder is unpredictable. The purpose of this study is to identify those critical conditions when acetylene cylinders burst and explode in fires. In the present study, acetylene cylinders were exposed to fire conditions. For this purpose, a woodpile as a source of fire was chosen, tested, and evaluated. In addition to the fire condition, this option guaranteed reproducibility and similar conditions for all tests. The individual cylinders were equipped with thermocouples measuring the shell temperature, and half of them were prepared in order to measure the temperatures inside the cylinder. An important factor was the measurement of the amount of pressure that was achieved during the destruction of the cylinder. For this purpose, a pressure transducer was attached to the outlet of the cylinder valve. Exposed to direct fire, they can explode in 10 min, which was confirmed. The critical pressure of 40 bar has been reached in 6 min, followed by destruction after 7 min in fire. Cylinders with internal thermocouples were destroyed when lower pressure was achieved. This confirms the fact that any change of the pressure cylinder affects the original properties. After the tests, the fragments of the selected cylinders were subjected to material tests. The results obtained in these tests are the main source of information for understanding the behavior of acetylene cylinders in fire and the possibility of increasing the safety of intervening rescue services in an emergency.
Tetrafluoroethylene (TFE) is an industrial scale starting material e.g. for polymer production (PTFE, FEP). When ignited the chemically unstable TFE is capable of decomposing in an explosive way. Explosion propagation through pipe systems of production plants have led to damage and fatalities within the last seven decades.
Incident analyses identified compression heat a relevant source of ignition. Chemical plants consist of pipes, vessels, separating valves, strainers and other components. Before restarting the process after maintenance work, different parts of the plant components could be filled with TFE, nitrogen or air at different initial pressures ranging from vacuum or atmospheric to TFE at operating pressure. Valve opening procedures may cause a temperature increase in the gas phase. Compression takes place at polytropic conditions. Heat losses cannot be neglected. The temperature development in the gas depends upon the surface to volume ratio of the enclosure, geometrical influences, the state of gas flow, how fast the valve opens, and the heat capacity of the gas being compressed.
Laboratory scale tests (Meyer, 2009) revealed ignition of TFE/air due to compression heat. Tests in pipes of 28 mm inner diameter, i.e. already industrial scale, were performed by (Kluge et. al., 2016). In the present contribution initial test results from a 63 mm pipe will be compared with existing 28 mm pipe data. A description of the experimental setup as well as an explanation of the hazard diagram will be given.
Furthermore, a method allowing for the identification of hazardous conditions will be discussed.
Bereits einfache Rohreinbauten wie 90°-Rohrbögen erhöhen den Turbulenzgrad einer Strömung signifikant. Bei Explosionsversuchen von Propan/Luft-Gemischen in einer DN150-Rohrleitung mit einem 90°-Rohrbogen wurden sowohl stark beschleunigte Deflagrationen als auch Detonationen mit maximalen Explosionsdrücken von über 65 bar (abs.) beobachtet.