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- Biofuels (7)
- BAM-Liste (6)
- Sealing materials (6)
- Biodiesel (5)
- Korrosionsbeständigkeit (5)
- Polyethylene grades (5)
- Tensile properties (5)
Organisationseinheit der BAM
- 3 Gefahrgutumschließungen; Energiespeicher (4)
- 3.2 Gefahrguttanks und Unfallmechanik (4)
- 2 Prozess- und Anlagensicherheit (2)
- 2.1 Sicherheit von Energieträgern (2)
- 8 Zerstörungsfreie Prüfung (2)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (2)
- 8.4 Akustische und elektromagnetische Verfahren (2)
- 8.6 Faseroptische Sensorik (2)
- 9 Komponentensicherheit (2)
- 9.6 Additive Fertigung metallischer Komponenten (2)
Biodiesel (FAME) from rapeseed is an environmentally friendly alternative to common fossil fuels. It is also suitable to serve as blending component to fuels like heating oil. If the fuel composition is changed, materials compatibility must be guaranteed. Adding polar biodiesel to nonpolar heating oil, changes the blend’s solvency and might cause swelling, extraction and solvation of polymers. The objective of this research was to investigate the compatibility of polymeric materials, which are commonly used for components in middle distillate facilities, along with blends of heating oil and 20 % biodiesel (B20). For this propose, ACM, HNBR, FKM, PE, PA 6, POM, PUR and PVC were exposed to heating oil and B20 for 42 and 84 days at 40 °C. In addition, the polymers HNBR, FKM, PA, POM and PVC were also exposed at 70 °C. Furthermore, the resistance of polymers in eight-year aged B10 at 40 °C was evaluated. Ageing of biodiesel increases acidity which might propagate polymer corrosion. The materials were evaluated as resistant, if the loss in tensile properties (tensile strength and elongation at break) and Shore hardness remained under 15 % compared to the initial unexposed material values. For investigations under compressed conditions, the compression set was determined for specimens of ACM, FKM and HNBR after exposure in heating oil B0 and B20 for 3,7,14, 28, 56 and 90 days at 40 °C according to ISO 815-1. It was found that the resistance in B20 at 40 °C was given for all tested polymers except PUR. In the 8 years aged B10, PUR and POM were not compatible and ACM just conditionally compatible. At 70 °C, FKM and PVC were resistant in B20, whereas HNBR and PA 6 were not compatible. Swelling occurred for the elastomers ACM, HNBR and PUR.
The feasibility study „AGIFAMOR. Ageing infrastructures – distributed acoustic monitoring of pipes” is an interdisciplinary research project at BAM internally financed from 2015 to 2018. Therefore, the quite young fibre optic sensing technology of distributed acoustic sensing (DAS) was investigated to possibly be extended towards a global condition monitoring system for pipelines operating in real time.
DAS is a highly dynamic fibre optic sensing technology based on the method of coherent optical time domain reflectometry (C-OTDR). DAS allows capturing strain changes in the range of kHz. For the experimental work, the most suitable application yielding an optimum sensitivity was proven by wrapping a standard single-mode silica fibre around the pipe.
The DAS sensitivity was investigated regarding the detection of 1) incidents that initiate propagation of acoustic waves in the pipe wall, 2) changes inside the pipeline causing altered flow and 3) damage development in the pipe wall. Therefore, several testing setups in laboratory as well as in real scale were realized. For comparison purposes, experiments were accompanied by acoustic emission analyses and by measurements with accelerometers.
DAS was found to be very sensitive to gas ignition and its propagation across the pipe. Furthermore, the ability of DAS to detect and localize acoustic signals associated with pipeline leakage was demonstrated. The detection of crack formation and propagation within the pipe wall by means of DAS was studied during bending tests on several pipe segments, but was not proven so far with certainty. As expected, these studies turned out as the most difficult challenge due to the random occurrence and transient nature of microscopic damage phenomena.
Biofuels including ethanol and biodiesel (FAME) represent a renewable fuel alternative to petroleum-derived transport fuels. The aim of this work was to study the interaction between high density polyethylene (HDPE) with permeation barriers in form of polyamide (PA) and fluorination, and biofuels such as E85 (fuel with 85 % ethanol), biodiesel and B10 (heating oil with 10 % biodiesel). 10 l jerrycans made of polyethylene with permeation barrier of PA were filled with E85 and biodiesel and exposed to temperatures of 20 °C and 40 °C for 5 years. Half of the 20 l jerrycans of HDPE for filling with B10 were fluorinated at the inner layer to prevent permeation before the exposure. Tensile properties were determined once a year, and FTIR-spectroscopy was used to evaluate possible changes.
The tensile properties tensile strength and breaking elongation of HDPE jerrycan cuttings with permeation barrier decreased, but not significantly, after immersion in E85, biodiesel and B10. The elasticity modulus of the polyethylene grades was especially reduced during exposure to E85.
The FTIR spectra of HDPE jerrycan cuttings with permeation barrier showed that immersion tests for five years with the test fuels at 20 °C and 40 °C did not lead to a decomposition of the permeation barriers.
The monitoring of oil and gas pipelines by means of distributed fibre optic sensors is becoming common. The most recent development in the field of fibre optic sensing is the distributed acoustic sensing (DAS), which allows to detect and to localize third party threats to pipelines. For this purpose, fibre optic telecommunication cables located close to the pipelines are usually used. However, DAS carries a far greater potential for continuous condition monitoring of pipelines.
The interdisciplinary research project AGIFAMOR (Ageing Infrastructures – Fibre Optic Monitoring of Pipes) at BAM investigates a new technical approach to extend the application field of DAS towards the detection and localization of acoustic signals that indicate critical alterations and certain damage scenarios originated from within the pipeline or the pipe wall. Therefore, the optical fibre sensors are applied onto the pipe itself and the application procedure towards an optimal acoustic signal transduction is optimized.
A number of laboratory scale experiments were performed focusing on the signal transmission of acoustic signals as well as the detection of damages in the pipe wall by means of DAS. Furthermore, real-scale tests on a pipeline DN100 of 38m length have been carried out at the BAM test site for technical safety (BAM-TTS) to study the detection and localization of leaks and of changing flow profiles due to corrosion or sedimentation processes.
Polyethylene terephthalate (PET) is used as material for packagings for the transport of dangerous goods due to its high strength and stiffness. For this reason, the wall thickness and weight of the packagings can be reduced.
According to the European dangerous goods regulations RID and ADR, samples of PET design types of packagings for dangerous goods must be pre-stored with the original filling good for six months at 23 °C, before the design type tests can be carried out. For packagings made of polyethylene (PE) tests to prove the stress cracking resistance by using laboratory methods are possible to reduce time and costs. Therefore, standard liquids, simulating the different types of damaging effects on PE are defined in RID and ADR. However, there is no information and research available about the damaging mechanisms on PET, especially regarding to stress cracking resistance and test methods.
One laboratory test method is the Full Notch Creep Test (FNCT), which was developed for polyethylene (PE) and is described in the standards EN ISO 13274 and EN 15507. It was investigated whether testing specimens made of PET with a full coplanar notch around the middle of the specimens show weakening after the impact of a tensile force in the standard liquid (5 % wetting solution) at 50 °C. The tests showed that this method couldn’t be used for PET because the specimens broke during notching due to the high brittleness of PET. Another disadvantage is the very time-consuming temper process for twelve hours after molding of the sheets.
Another test method is described in BAM’s Dangerous Goods Rule BAM-GGR 015. This test was carried out with 1l PET bottles, which were filled with a 5% wetting solution and mounted with a clamping tool for 28 days at 40°C. Tensile test specimens were cut out afterwards from the middle of the bottles in the deformed areas. The tensile properties of the PET specimens couldn’t be determined due to the hardness of the material.
The only test method to provide information about the stress cracking resistance of PET was to perform stacking tests with PET design types of packagings. 1l bottles made of PET were filled with the standard liquid (5 % wetting solution) and stored with a stacking load for 28 days at 40°C according to EN ISO 16495. The test bottles of PET passed the stacking tests.
In conclusion, samples of PET design types of packagings for dangerous goods must be pre-stored with the original filling good for six months at 23 °C, before the design type tests can be carried out.
Pipelines and industrial piping systems are particularly relevant regarding technical safety, availability and maintenance. Large flow rates of hazardous substances imply that even smallest leakages can lead to high environmental impacts. Therefore, and to ensure the availability of infrastructure, an early detection and localization of potentially hazardous degradations to the walls (e.g. cracks, pittings, sedimentation, etc.) of the containments is necessary. However, in many cases it is not feasible to equip pipelines with a large number of point sensors at reasonable expense.
The principle of distributed fibre optic sensing relies on one single optical fibre, which simultaneously acts as a spatially continuous sensor as well as the signal transducer. Therefore, extensive structures can be provided with this type of sensor with comparatively low efforts.
As a consequence, monitoring oil and gas pipelines using distributed fibre optic sensors is on the upswing. Besides the established methods to measure temperature and strain, distributed acoustic sensing (DAS) has lately received considerable attention as a means to detect and localize third party threats to pipelines (approach of vehicles, digging, mechanical manipulation).
The so far not utilized potential of DAS as a means for continuous condition monitoring of pipes by detecting and localizing acoustic signals that point to certain damage scenarios, is currently under investigation in an interdisciplinary research project at BAM (AGIFAMOR, Ageing Infrastructures – Fibre Optic Monitoring of Pipes).
In order to qualify distributed acoustic fibre optic sensors for this application area, we especially focus on detecting and identifying the relevant acoustic emissions of interesting degradations as well as on the optimal way of application of the optical fibres to the specimen to achieve an optimal signal transmission of acoustic signals.
Rohrleitungssysteme sind aufgrund ihrer Funktion und Ausdehnung für den Betrieb, die Verfügbarkeit und die Sicherheit von Industrieanlagen von besonderer Bedeutung. Die bisher in definierten Intervallen durchgeführten, wiederkehrenden Prüfungen zur Sicherstellung leckagefreier Rohrleitungen sind kostenintensiv und mit einem erhöhten Aufwand verbunden.
Mit dem interdisziplinären Forschungsprojekt AGIFAMOR (Ageing Infrastructures – Akustisches Monitoring von Rohrleitungen) arbeitet die BAM an der Entwicklung und Erprobung einer örtlich und zeitlich kontinuierlichen Zustandsüberwachung von Rohrleitungen basierend auf einem faseroptischen akustischen Messsystem, welches einen vergleichsweise geringen Installationsaufwand der Sensoren erfordert. Mit diesem Verfahren sollen vor allem betriebsbedingte Schädigungen infolge von Korrosion sowie daraus entstehende Pittings oder Risse erkannt und damit Leckagen verhindert werden.
Im Rahmen einer Machbarkeitsstudie zum Teilaspekt „Detektion von Risswachstum“ wurde ein 2,5 m langes, definiert vorgekerbtes Stahlrohr mit der faseroptischen Sensorik (FOS) ausgestattet und quasistatisch unter 4-Punkt-Biegung belastet. Mit fortschreitender Belastung wächst, ausgehend vom vorhandenen Außenumfangskerb, ein Riss im Stahlrohr bis zum Erreichen der Leckage – in der Praxis ein gefährliches Schadensszenario.
Parallel zur FOS erfolgten Messungen mit Schallemissionssensoren, Beschleunigungssensoren und Potentialsonden, deren Ergebnisse die Interpretation der FOS-Messergebnisse unterstützen sollen.
Changes in fuel composition and the introduction of alternative fuels often create problems of corrosion and degradation in materials. The objective of this research was to determine the corrosion behaviour of commercial metallic tank materials (unalloyed steels, austenitic CrNi- and CrNiMo-steels, aluminium and its alloys) in fuels and heating oil with admixtures of biogenic sources, such as gasoline with addition of ethanol (E10, E85), pure biodiesel and heating oil with 10 % biodiesel (B10).
Metallic tank materials were evaluated as resistant in a liquid if the annual corrosion rate due to uniform corrosion did not exceed 0.1 mm/year, and localized corrosion effects in the form of pitting corrosion, stress corrosion cracking and crevice corrosion did not occur.
The corrosion rates of the tank materials after exposure to E10, E85, non-aged and two-year aged pure biodiesel, and non-aged and one-year aged heating oil B10 for four weeks at 50 °C, according to DIN 50905/4, were well below the limit of 0.1 mm/year. For the unalloyed steels, the formation of rust was observed independently of the biofuels amount of ageing. U-bend specimens made of unalloyed steel were not damaged in form of stress corrosion cracking in all test fuels at this test temperature.
The objective of this research was to determine the resistance of frequently used sealing materials such as EPDM, FKM, FVMQ, CR, CSM, IIR, NBR, PA, PUR and VMQ in aged biodiesel and heating oil B10 with 10 % biodiesel.
The mass, tensile strength, breaking elongation and Shore hardnesses of the test specimens were determined before and after exposure in non-aged, one-year, two-year, three-year and four-year aged biodiesel and B10 at 20 °C, 40 °C and 70 °C.
A threshold for the reduction in tensile properties and Shore hardness is not set in the international standards. Therefore, a threshold of 15 % was set for the evaluation of the compatibility. The decrease in tensile properties and Shore hardness increased with the age and the temperature of the biodiesel and the heating oil.
The age of the biodiesel was not relevant for the sealing materials CR, CSM, EPDM, IIR and NBR, which were generally not resistant to biodiesel and B10. FKM and PA showed high compatibility in non-aged and aged biodiesel. FVMQ and PA could be evaluated as resistant in non-aged and aged B10 at 20°C and 40°C, whereas FKM was resistant up to 70°C despite of the age of B10.
Impact of biocomponents in the fuel and heating oil on the compatibility of sealing materials
(2016)
The objective of this research was to determine the resistance of frequently used sealing materials such as FKM, FVMQ, VMQ, EPDM, CR, CSM, IIR, PA, NBR and PUR in fuels and heating oil with and without admixtures of biogenic sources such as E10, diesel fuel with 5 % biodiesel, non-aged and 2 year aged B10 (heating oil with 10 % biodiesel), pure diesel, standard heating oil and premium grade fuel Super plus at 20 °C, 40 °C and 70 °C.
Mass, tensile strength and breaking elongation of the test specimens were determined before and after the exposure for 84 days in the fuels. The visual examination of some elastomer test specimens clearly showed the great volume increase until break or partial dissolution. Shore hardness A and D (for PA) were determined before and after exposure of the test specimens in the biofuels for 42 days.
There is not determined a threshold for the reduction in tensile properties and Shore hardness in the international standards. Therefore a threshold of 15 % was determined for the evaluation of the compatibility.
In summary, it can be therefore stated that the chemical resistance of the fluoropolymers FKM and FVMQ in fuels and biofuels is the best one.