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For many sealing applications rubber O-rings are applied due to their special properties and easy use. In many applications as e.g. in aviation, traffic or process technology the material can be exposed to a variety of conditions during operation as e.g. low temperatures, elevated temperatures and different media. Therefore, it is important to know the material behaviour and the seal performance under those conditions. Additionally ageing of seals is an important factor which has an influence on the long term reliability.
In this contribution we would like to discuss different aspects affecting the seal performance, lifetime estimation and address open questions which should be addressed to come to a deeper understanding of these seals commonly understood as typical machine elements.
Results of running investigations at the Bundesanstalt für Materialforschung und -prüfung (BAM), Division 3.4 “Safety of Storage Containers” are presented and discussed.
An analysis has been presented pertaining to the use of a convex
bottom tank shape instead of an elliptical, for a road tanker.
Two analyses have been made, concerning the static and the dynamic
relative performance expectations of such tank shape when compared
with the elliptical shape performance.
The outputs of both analyses suggest that the level of average benefit
due to using the proposed shape, is around 10%, with a maximum
benefit observed in the dynamic performance in the case of the
minimum fill level.
Correlation between static and dynamic outputs. Manufacturing.
Compared with the original time-temperature superposition (TTS) principle, an extended non-linear time-temperature equivalent (TTE) principle is suggested in this work. Results shown us, all application of TTS and most of the TTE parameters, for example, the Orr-Sherby-Dorn, Manson-Succop, Larson-Müller, Manson-Haferd, Mendelson-Roberts-Manson parameters and the more general ‘single metamodel’ from Haque–Stewart are special cases of the new suggested principle. The merits of this new method are discussed.
Avoiding road crashes has been the purpose behind many specialized software and hardware systems, involving both active and passive safety principles. Global Positioning technologies were incorporated into the transportation systems with the main purpose of acquiring the position of the vehicle under a continuous basis, for security and economy purposes. However, the GPS data can also be used for assessing the level of safety at which the vehicle is driven. On the basis of the essential data available from commercial GPS devices, in this paper we propose a combined performance measurement to assess the road safety level at which the vehicle is being driven. Such performance measure uses GPS data of the vehicle displacement, including the speed and the acceleration, as well as the course (latitude and longitude coordinates), in an integral driving assessment formulation that can run in real time. Results from the experimental use of this formulation suggest that the level of safety in the driving is time dependent, and that there are risky situations when different factors converge.
The proposed mechanism is based on a cam design and is independent of any external energy source.
Conclusions
Issue 1: An accelerated wear tip of the cam shaped journal .
Issue 2: The spherical rollers proposed for the bearings would be underused, as the contact force will be downwards, and such bearing has supporting capacity in both vertical directions.
A general explanation of reduced volume method was introduced. This has allowed the simulation runs much faster without compromising the failure prediction of the multiscale fibre break model. The validation results with a material samples were shown. A certain mesh configuration to evaluate the cylinder has also been found to be the most effective in terms of computation time and prediction accuracy.
The reduced volume method has been studied using the fibre break model from Mines ParisTech. This method allows less 3D finite elements to be used for predicting the failure of real scale composite structures. A favourable comparison results with racetrack specimens has been achieved. However, the comparison study with a type IV pressure vessels still requires more Evaluation.
In this presentation, the history and actual situation of the German nuclear waste management policy of spent fuel (SF) and high-level waste (HLW) is reported. Beside the description of the restructuration of responsible authorities and organizations in Germany, the principle of dry interim storage of SF and HLW in dual purpose casks is explained. The need for extended interim storage towards disposal implicates additional challenges for the nuclear waste management strategy in Germany. (Extended)interim storage, subsequent transportation, and final disposal are closely linked. Integrated approaches concerning waste package designs and operations are supposed to be beneficial for the establishment of efficient long-term SF and HLW management strategies. Knowledge management and staff recruiting, education and training during phase out and beyond nuclear power plant operation are major issues.
At BAM, which is a federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes assessment of elastomeric seals applied in the casks. One of the aims is to identify a suitable method for estimating the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) for up to five years. In order to assess sealability, O-rings were aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings were aged as well. In order to understand the underlying ageing mechanisms in each material, material properties such as hardness, density and tensile properties were examined. Additionally, compression set (CS), which represents the recovery behaviour of a seal after release from compression, is measured. For obtaining results closely related to practical conditions, O-rings with a full-scale cord diameter of 10 mm were aged. However, this set-up can lead to heterogeneous ageing caused by diffusion-limited oxidation (DLO) effects especially for HNBR, resulting in distorted bulk properties such as compression set. However, if DLO-affected data is excluded, extrapolations of CS data are possible using time-temperature shifts.
For selecting an appropriate end-of-lifetime criterion, leakage rate measurements were performed, since leakage rate is the only characteristic directly correlated to the performance of the sealing system. A significant increase in leakage rate was considered as the end of the lifetime. However, the O-rings remained leak tight under static conditions even though material properties had already degraded strongly. For this reason, a modified, more demanding leakage test involving a fast small decompression of the seal was developed that allowed determining a more conservative end-of-lifetime criterion with a safety margin for EPDM seals. FKM, which is a very heat and oxidation resistant material, exhibited only little degradation, even though it had the smallest activation energy.
Sicherheitskonzepte werden für die verschiedenen Szenarien für Lithiumakkus benötigt: Vor allem für den Bereich der Lagerung gibt es im Moment nur wenige Vorgaben. Im Vortrag werden verschiedene Brandschutzkonzepte vorgestellt. Für die Lagerung werden Empfehlungen ausgesprochen, die teilweise an die Vorgaben der Transportvorschriften anknüpfen.
BAM is the German Federal Institute for Materials Research and Testing and the competent authority for mechanical and thermal safety assessment of transport packages for spent fuel and high level waste. In context with safety assessment of RAM packages BAM performed numerous drop tests in the last decades. The tests were mostly accompanied by extensive and various measurement techniques especially by instrumented measurements with strain gages and accelerometers.
The procedure of drop testing and the resulting measurement analysis are the main methods to evaluate the safety against mechanical test conditions. Measurement techniques are dedicated to answer questions in regard to the structural integrity of a RAM package, the mechanical behaviour of the prototype as well as of its content under impact conditions.
Test results like deceleration-time functions constitute a main basis for the validation of assumptions in the safety analysis and for the evaluation of numerical calculations. In this context the adequate selection of accelerometers and measurement systems for the performance of drop tests is important. Therefore it is not only necessary to find suitable positions for the accelerometers at the test specimens, but also to consider technical boundary conditions as e.g. temperature. Accelerometers are widely used for the measuring of motion i.e. velocity or the displacement of the rigid cask body, vibration and shock events.
Acceleration measurements as well as their analysis are often very complex and extensive also because they are in turn embedded in complex drop test experiments having to consider difficult boundary conditions as for example very low specimen temperatures, large drop heights and sophisticated drop orientations of the specimen. In every case special instruments and adequate technical equipment is required to accelerations under these and transient shock conditions which are characterized in our case by impact times in the range of a few milliseconds up to perhaps 100 Milliseconds naturally depending on container design and drop test conditions as drop height and target.
The paper gives an overview of drop tests under kinematic aspects performed with RAM packages. Furthermore, experimental advancements of accelerometer instrumentation within drop testing, e.g. the characteristics and possibilities of accelerometers, behavior of accelerometers and various influence factors are shown.
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.
The containment systems of transport and storage casks for spent fuel and highlevelradioactive waste usually include bolted lids with metallic or elastomeric seals. The mechanical and thermal loadings associated with the routine, normal and accident conditions of transport can have a significant effect on the leak tightness of such containment system.
Scaled cask models are often used for providing the required mechanical and thermal tests series.Leak tests have been conducted on those models.
It is also common practice to use scaled component tests to investigate the influence of deformations or displacements of the lids and the seals on the standard leakage rate as well as to study the temperature and time depending alteration of the seals.
In this paper questions of the transferability of scaled test results to the full size design of the containment system will be discussed.
The first German package design approval certificate for a dual purpose cask intended for loading with damaged spent nuclear fuel was issued recently. BAM as part of the competent authority system in Germany carried out a comprehensive assessment procedure with respect to the mechanical and thermal design, the release of radioactive material and the quality assurance aspects of manufacturing and operation. Packages for the transport and storage of radioactive material have been assessed by BAM for many years, thus the common assessment procedure is well-known and good practice. Up to now only SNF without defects or HLW with well-defined properties were designated for long-term Interim storage and transports afterwards. Due to Germany’s nuclear phase out all other kinds of spent nuclear fuel in particular damaged spent nuclear fuel shall be packed as well. Damaged spent nuclear fuel needs a tight closure with Special encapsulations and clearly defined properties in Germany. In addition, these encapsulations shall be long-term durable, because they are not accessible after loading in a packaging within periodical inspections. The main difference to Standard package components is that encapsulations with a permanent closure achieve their specified conditions not after manufacturing but only during operation, after loading and closing. To ensure compliance with the specific conditions, special measures for quality assurance are necessary during operation of each encapsulation, e.g. drying and sealing, which were assessed by BAM. The present paper gives an overview of the conducted assessment from BAM and point out the findings concerning to the special closure lid of the approved encapsulation, which is screwed and welded. A wide verification concept is necessary to show the specific tightness under transport conditions. Together with quality assurance measures during first operation steps these encapsulations with damaged spent nuclear fuel can be handled like standard fuel assemblies in approved package designs.
Tanks sind für normale Beförderungsbedingungen gebaut und zugelassen! Tankkörper müssen nach Normen (siehe 6.8.2.6 RID/ADR) oder nach einem von der zuständigen Behörde anerkannten technischen Regelwerk entworfen und gebaut werden Schweißverbindungen müssen nach Regeln der Technik ausgeführt werden. Unterdruck im Tank ist zu berücksichtigen (Berechnung, Vakuumventil). Beständigkeit – Gefahrgut darf mit Tankwerkstoff nicht gefährlich reagieren oder die Werkstoffe merklich schwächen!
Aus Rapsöl gewonnener Biodiesel ist eine umweltfreundliche Alternative zu fossilen Energiequellen. In der Europäischen Union, in der 80 % der ölhaltigen Brennstoffe importiert werden müssen, besteht zudem ein Interesse, die Abhängigkeit von exter-nen Ölversorgern zu reduzieren.
Bei jeder Veränderung der Zusammensetzung eines Brennstoffs muss auch die Ma-terialverträglichkeit gewährleistet bleiben. Es stellt sich die Frage, ob Elastomere im Vergleich zu reinem Heizöl auch in Heizöl mit 20 % Biodiesel (B20) beständig sind.
Die Polarität des Biodiesels erhöht die Quellung und fördert die Permeation und Ex-traktion. Sowohl Quellung als auch Extraktion bedingen Änderungen der physikali-schen Eigenschaften der Elastomere. Extraktion verändert die chemische des Heiz-öls. Diese chemischen Veränderungen können auch den Abbau (Hydrolyse und Oxi-dation) der Polymere durch das Herauslösen von Additiven und Stabilisatoren be-schleunigen.
Ziel dieser Arbeit war die Bestimmung der Beständigkeit der Elastomere ACM (Poly-acrylatkautschuk), HNBR (Hydrierter Acrylnitrilbutadienkautschuk), FKM (Fluorkaut-schuk) und PUR (Polyurethan) in Heizöl und im Heizölgemisch B20.
Prüfkörper der Elastomere wurden für 42 Tage (Härteprüfung) und 84 Tage (Zugprü-fung) bei 40 °C ausgelagert. Anschließend wurde die Änderung der Masse, Shore Härte A, Zugfestigkeit, und Reißdehnung bezogen auf die Werte vor der Aus-lagerung bestimmt. Die weniger zur Quellung neigenden Elastomere FKM und HNBR wurden zusätzlich bei 70 °C ausgelagert.
Um die Elastomere im verpressten Zustand zu testen, wurde der Druckverformungs-rest nach DIN ISO 815 bestimmt. Hierzu wurden zylindrische Prüfkörper aus ACM, HNBR und FKM verpresst und in Heizöl und Heizöl mit 20 % FAME für 3, 7, 14, 28, 56 und 90 Tage bei 40 °C ausgelagert. Anschließend wurde über die Dickenmes-sung der Druckverformungsrest ermittelt. Zum Vergleich wurden Prüfkörper verpresst und ohne Medium bei 40 °C ausgelagert.
In den internationalen Normen wurde kein Grenzwert für die Veränderung der Zugei-genschaften und der Härte für eine positive Bewertung der Beständigkeit festgelegt. Deshalb wurde in der BAM ein Grenzwert von 15 % für die Beständigkeitsbewertung herangezogen.
Bei 40 °C lag die Änderung der Zugeigenschaften und der Shore Härte von ACM, HNBR und FKM in Heizöl und in B20 unter 15 %. Folglich sind ACM, HNBR und FKM bei 40 °C in Heizöl und in B20 beständig. PUR ist bei 40 °C in Heizöl beständig, je-doch nicht für eine Verwendung in B20 geeignet, da sich die Zugfestigkeit und Reiß-dehnung um 50 % vermindert haben.
Bei 70 °C ist FKM in Heizöl und B20 beständig, wohingegen HNBR an seine Einsatz-grenzen gelangt und unbeständig ist, in B20 haben sich die Zugfestigkeit um 40 % und die Reißdehnung um 50 % reduziert.