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- Aged biodiesel (2)
- Aged heating oil with 10% biodiesel (B10) (2)
- Biodiesel (2)
- Bioethanol (2)
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- Corrosion resistance (2)
- Dangerous goods packaging (2)
Eingeladener Vortrag
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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 chemical industry has expressed great interest in using polyethylene terephthalate (PET) as material for packagings for the transport of dangerous goods. Due to the high strength and stiffness of PET, the wall thickness and weight of packagings can be reduced.
The aim of this work was to find a laboratory test method for the determination of the stress cracking resistance of PET. One 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 a wetting solution at 50°C. Unfortunately, this method couldn’t be used for PET because the specimens broke during notching due to the high brittleness of PET. The molding of the sheets and the following temper process for twelve hours are very time-consuming, Another possibility is laid down 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.
In conclusion, the only way 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 a 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.
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.
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.
The objective of this research was to determine the resistance of frequently used sealing materials such as fluorocarbon rubber (FKM), fluorosilicone rubber (FVMQ), silicone rubber (VMQ), ethylene-propylene-diene rubber (EPDM), chloroprene rub-ber (CR), chlorosulfonated polyethylene (CSM), butyl rubber (IIR), acrylonitrile buta-diene rubber (NBR), polyester urethane rubber (PUR) and polyamide (PA) in non-aged/aged biodiesel and heating oil with 10 % biodiesel at 20 °C, 40 °C and 70 °C. Mass, tensile properties and Shore hardness A/D (for polyamide) of the test speci-mens were determined before and after the exposure for 84/42 days in the aged and non-aged fuels of different age.
Biodiesel fuels are easily oxidized and contain acids and water. The sealing materi-als: acrylonitrile butadiene rubber, butyl rubber, chloroprene rubber, chlorosulfonated polyethylene and ethylene-propylene-diene rubber and were generally not resistant to biodiesel and heating oil with 10 % biodiesel. Fluorocarbon rubber, fluorosilicone rubber and polyamide were the most resistant materials in all tested fuels up to 70 °C. The degree of damage to the sealing materials increased with higher test temperatures and the age of the fuels.
Plastic storage tanks for heating oil have been on the market since the early 1970s in Germany, mainly made from polyethylene grades. Tank manufacturers and experts examining the tanks recommend the replacement of the tanks to ensure the safety after a period of 30 years. The tank manufacturer is legally obliged to specify the service life of the tanks.
Polyethylene is subject to ageing by alteration of the properties during its life cycle. A distinction is made between internal and external ageing processes. The internal ageing, such as the breakdown of internal stresses, post-crystallization, phase sepa-ration of multicomponent systems and plasticizer migration is attributed to thermodynamically instable conditions of the plastic material. The external ageing in form of stress cracking, fatigue cracking, thermooxidative degradation or swelling is based on physical or chemical effects of the environment of the polyethylene grade. The degree of ageing and the nature of the degradation process mainly depend on the chemical degradation of the polyethylene, the wall thickness of the tank and the environmental conditions. There are no results available on the long-term behaviour of the polyethylene grades used as materials for heating oil storage tanks, especially after a service life of more than 25 years.
The aim of this investigation was the determination of the factual degree of damage in comparison to the uncontaminated polyethylene grades. Data on the melt flow rate (MFR) and density of the used polyethylene grades are available because the BAM was the competent authority for the approval of the plastic heating oil storage tanks until the end of the 1980s.
The technical service of specialist companies for fuel tank disposal supplied tank sections from the bottom, the shell and the roof of 8 segregated heating oil storage tanks. Some of the tanks had been in service for more than 30 years. Two polyethylene grades mainly were used as materials for these tanks over this time. The determination of the MFR according to EN ISO 1133 and the FTIR spectroscopy followed standard test methods.
The highest average percentage increase in the MFR was determined as 31- 43 % for the bottom section of the tanks, for both the inner shell and the outer shell. The lowest increase in MFR was measured for the top of the tank, with 6 - 12 % for the inner shell and 0 - 8 % for the outer shell. The tank shell sections had an average percentage increase in MFR of 10 - 33 % for the inner shell and of 14 - 40 % for the outer shell.
The oxidative damage of the polyethylene grades was highest in the bottom area due to the permanent contact with the heating oil and degradation products.
The microtome cuttings were analyzed with image-guided infrared microscopy in the transmission mode and confirmed the results obtained with the MFR measurements.
In summary it can be concluded that the oxidative damage of the polyethylene grades after long-term contact with heating oil is relative low.