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- Monitoring (2)
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- Acoustic emission (1)
- Aged biodiesel (1)
- Aged heating oil with 10% biodiesel (B10) (1)
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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.
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.
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.
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.
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.