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- 3 Gefahrgutumschließungen; Energiespeicher (27)
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- 8 Zerstörungsfreie Prüfung (3)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (3)
Eingeladener Vortrag
- nein (89)
Ziel dieser Untersuchungen war die Bewertung der Beständigkeit häufig eingesetzter Dichtungswerkstoffe, wie Fluorkautschuk (FKM), Fluorsiliconkautschuk (FVMQ), Siliconkautschuk (VMQ), Ethylen-Propylen-Dien-Kautschuk (EPDM), Chloroprenkautschuk (CR), chlorsulfoniertes Polyethylen (CR), Butylkautschuk (IIR), Acrylnitril-Butadien-Kautschuk (NBR), Polyes-terurethankautschuk (PUR) und Polyamid (PA) in Kraftstoffen und Heizöl mit und ohne bioge-ne Zusätze bei 20 °C, 40 °C und 70 °C. E10 (Kraftstoff mit max. 10 % Ethanol), E85 (Kraftstoff mit 85 % Ethanol), Dieselkraftstoff mit max. 5 % Biodiesel, Super mit max. 5 % Ethanol, un-gealtertes und gealtertes B10 (Heizöl mit 10 % Biodiesel) sowie zum Vergleich reiner Dieselkraftstoff, Heizöl und Kraftstoff Super plus zählten zu den Testsubstanzen.
Masse, Zugfestigkeit und Bruchdehnung wurden von den Prüfkörpern vor und nach der 84-tägigen Auslagerung in den Kraftstoffen und Heizöl bestimmt. Die visuelle Begutachtung einiger Elastomerprüfkörper zeigte eindeutig die hohe Quellung bis zur partiellen Auflösung.
Die Shore-Härte A und D (für PA) der Prüfkörper wurden vor und nach der 42-tägigen Auslagerung in den Kraftstoffen bestimmt.
In den internationalen Normen wird zur Bewertung der Beständigkeit von Elastomeren kein Grenzwert der Reduzierung der Zugeigenschaften und der Shore-Härte definiert. Deshalb wurde für die Beständigkeitsbewertung ein Grenzwert von 15 % festgelegt. Zusammenfassend kann die Aussage getroffen werden, dass die Beständigkeit der Fluorpolymere FKM und FVMQ in den Kraftstoffen und Heizöl mit und ohne biogene Zusätze die beste ist.
Ziel dieser Untersuchungen war die Bewertung der Beständigkeit häufig eingesetzter Dichtungswerkstoffe, wie FKM, FVMQ, VMQ, EPDM, CR, CSM, IIR, PA, NBR und PUR in Kraftstoffen und Heizöl mit und ohne biogene Zusätze bei 20 °C, 40 °C und 70 °C. E10, E85, Dieselkraftstoff mit max. 5 % Biodiesel, ungealtertes und 2 Jahre gealtertes B10 (Heizöl mit 10 % Biodiesel), reiner Dieselkraftstoff, Heizöl und Kraftstoff Super plus zählten zu den Testsubstanzen. Masse, Zugfestigkeit und Bruchdehnung wurden von den Prüfkörpern vor und nach der 84-tägigen Auslagerung in den Kraftstoffen und Heizöl bestimmt. Die visuelle Begutachtung einiger Elastomerprüfkörper zeigte eindeutig die hohe Quellung bis zur partiellen Auflösung. Die Shore-Härte A und D (für PA) der Prüfkörper wurden vor und nach der 42-tägigen Auslagerung in den Kraftstoffen bestimmt. In den internationalen Normen wird zur Bewertung der Beständigkeit von Elastomeren kein Grenzwert der Reduzierung der Zugeigenschaften und der Shore-Härte definiert. Deshalb wurde für die Beständigkeitsbewertung ein Grenzwert von 15 % festgelegt. Zusammenfassend kann die Aussage getroffen werden, dass die Beständigkeit der Fluorpolymere FKM und FVMQ in den Kraftstoffen und Heizöl mit und ohne biogene Zusätze die beste ist.
Heizöllagerbehälter aus Polyethylenformstoffen werden seit Beginn der 70-iger Jahre in Deutschland hergestellt. Die Hersteller empfehlen zur Gewährleistung der Sicherheit nach Ablauf von 30 Jahren den Ersatz dieser Behälter. Polyethylenformstoffe unterliegen im Laufe ihrer Nutzungsdauer der Alterung durch die Veränderung ihrer Eigenschaften. Das Ausmaß der Alterung und die Art des Abbauvorganges hängen im Wesentlichen vom chemischen Abbau des Polyethylens, der Wanddicke des Behälters und den Umgebungsbedingungen ab. Bisher lagen keine Untersuchungen zum Langzeitverhalten der Polyethylenformstoffe vor, insbesondere nach einer Nutzungsdauer der Tanks über 30 Jahre. Ziel der Untersu-chungen war, den tatsächlichen Schädigungsgrad der Polyethylenformstoffe im Vergleich zu den unbelasteten Formstoffen zu ermitteln. Da die BAM bis Mitte der 90-iger Jahre für die Prüfungen und Gutachten zur Zulassung dieser Behälter zuständig war, sind die Werkstoffdaten noch vorhanden.
Als Untersuchungsmethoden wurden die Bestimmung der Schmelze-Masse-Fließrate (MFR) und die Fourier-Transformation-IR-Spektroskopie (FTIR) von Tankausschnitten aus dem Bereich des Bodens, des Mantels und des Daches von 10 ausgesonderten Behältern aus den Polyethylenformstoffen A und B herangezogen. Die Messungen der MFR der Tankaus-schnitte aus diesen Bereichen zeigten Unterschiede in den Werten in Abhängigkeit vom Ge-wicht (5 kg oder 21,6 kg), welches eingesetzt wurde. Eine Abnahme der MFR-Werte wurde für die größere Anzahl der Tankwandungsausschnitte aus dem Formstoff B nach einer Lebensdauer der Tanks > 30 Jahre gemessen. Dieser Formstoff wurde hauptsächlich durch innere Alterung infolge Vernetzungen, Verzweigungen und Weichmacherverlust und weniger durch oxidativen Abbau geschädigt. Die FTIR-Messungen der Proben aus dem Bereich des Bodens und des Mantels der Tanks zeigten, dass die Intensität der asymmetrischen/symmetrischen CH2 -Streckschwingungen im Bereich: 2800 - 2900 cm-1 und der CH2 -Biegeverformungsschwingung bei 1400 cm-1 aufgrund von Kettenspaltungen zugenommen haben. Die Intensität der Carbonylstreckschwingung C=O bei 1740 cm-1 ist niedrig. Sie ist ein Maß für die Oxidation des Polymerwerkstoffes.
Heizöllagerbehälter aus Kunststoffen (z.B. Polyethylen) sind für einen sicheren Betrieb von 30 Jahren, dem Zeitraum der Produkthaftung, ausgelegt. Die Tankhersteller empfehlen zur Gewährleistung der Sicherheit nach Ablauf von 30 Jahren den Ersatz dieser Behälter. Kunststoffe unterliegen im Laufe ihrer Nutzungsdauer der Alterung durch die Veränderung ihrer Eigenschaften. Das Ausmaß der Alterung und die Art des Abbauvorganges hängen im Wesentlichen vom chemischen Abbau des Kunststoffes, der Wanddicke des Behälters und den Umgebungsbedingungen ab. Aufgrund der Komplexität der Alterungsvorgänge sind Aussagen zum Langzeitverhalten bzw. zur Lebensdauer der Heizöllagerbehälter ohne geeignete Langzeitprüfungen problematisch. Bisher liegen keine Untersuchungen zum Langzeitverhalten der Kunststoffe vor, insbesondere nach einer Nutzungsdauer über 20 Jahre. In der BDH-Broschüre: Effiziente Systeme und erneuerbare Energien wird darauf hingewiesen, dass ca. 45 % der Heizöllagerbehälter aus Kunststoffen in Deutschland 26 Jahre und älter sind. Viele dieser Tankanlagen sind zudem noch nie von einem Sachverständigen überprüft worden. Schätzungen gehen davon aus, dass mehr als 10.000.000 Tankanlagen aus Kunststoffen in Deutschland vor 1987 errichtet wurden.
Ziel der Untersuchungen ist, den Schädigungsgrad der Kunststoffe im Vergleich zu den unbelasteten Werkstoffen zu ermitteln. Da die BAM bis Ende der 80-iger Jahre für die Zulassung dieser Behälter zuständig war, sind die Daten über den eingesetzten Werkstoff für den Vergleich noch vorhanden. Der Bundesverband Lagerbehälter e.V. und das Institut für Wärme und Oeltechnik (IWO) befürworten diese Untersuchungen, um eine Überalterung der Tankanlagen zu vermeiden. Diese Überalterung könnte die zukünftige Gefahr für die Heizöltankanlage sein, nicht der Wettbewerb mit anderen Energieformen.
Heizöllagerbehälter aus Polyethylenformstoffen werden seit Beginn der 70-iger Jahre in Deutschland hergestellt. Die Hersteller empfehlen zur Gewährleistung der Sicherheit nach Ablauf von 30 Jahren den Ersatz dieser Behälter. Polyethylenformstoffe unterliegen im Laufe ihrer Nutzungsdauer der Alterung durch die Veränderung ihrer Eigenschaften. Das Ausmaß der Alterung und die Art des Abbauvorganges hängen im Wesentlichen vom chemischen Abbau des Polyethylens, der Wanddicke des Behälters und den Umgebungsbedingungen ab. Bisher lagen keine Untersuchungen zum Langzeitverhalten der Polyethylenformstoffe vor, insbesondere nach einer Nutzungsdauer der Tanks über 30 Jahre. Ziel der Untersu-chungen war, den tatsächlichen Schädigungsgrad der Polyethylenformstoffe im Vergleich zu den unbelasteten Formstoffen zu ermitteln. Da die BAM bis Mitte der 90-iger Jahre für die Prüfungen und Gutachten zur Zulassung dieser Behälter zuständig war, sind die Werkstoffdaten noch vorhanden.
Als Untersuchungsmethoden wurden die Bestimmung der Schmelze-Masse-Fließrate (MFR) und die Fourier-Transformation-IR-Spektroskopie (FTIR) von Tankausschnitten aus dem Bereich des Bodens, des Mantels und des Daches von 10 ausgesonderten Behältern aus den Polyethylenformstoffen A und B herangezogen. Die Messungen der MFR der Tankaus-schnitte aus diesen Bereichen zeigten Unterschiede in den Werten in Abhängigkeit vom Ge-wicht (5 kg oder 21,6 kg), welches eingesetzt wurde. Eine Abnahme der MFR-Werte wurde für die größere Anzahl der Tankwandungsausschnitte aus dem Formstoff B nach einer Lebensdauer der Tanks > 30 Jahre gemessen. Dieser Formstoff wurde hauptsächlich durch innere Alterung infolge Vernetzungen, Verzweigungen und Weichmacherverlust und weniger durch oxidativen Abbau geschädigt. Die FTIR-Messungen der Proben aus dem Bereich des Bodens und des Mantels der Tanks zeigten, dass die Intensität der asymmetrischen/symmetrischen CH2 -Streckschwingungen im Bereich: 2800 - 2900 cm-1 und der CH2 -Biegeverformungsschwingung bei 1400 cm-1 aufgrund von Kettenspaltungen zugenommen haben. Die Intensität der Carbonylstreckschwingung C=O bei 1740 cm-1 ist niedrig. Sie ist ein Maß für die Oxidation des Polymerwerkstoffes.
In Germany the “BAM-List - Requirements for Tanks for the Transport of Dangerous Goods” is the basis for substance-related prototype approvals for tank Containers undertaken by the BAM1 - Federal Institute for Materials Research and Testing. Compatibility evaluations of selected metallic materials as well as of polymeric gasket and lining materials under the influence of approximately 7200 dangerous goods have been published in the BAM-List since 1989.
The ferritic Steel UNS S44400 (X2CrMoTil8-10, 1.4521) was originally developed as alternative for the austenitic grade AISI316L (X2CrNiMo 17-12-2, 1.4404). Due to its characteristic profile this Steel was qualified for applications requiring high strength values at concomitant adequate corrosion resistance. Because of the lack of Nickel this Steel is a cost-efficient alternative to the Ni-containing austenites. No corrosion test results of UNS S44400 under the influence of dangerous goods were published in the BAM-List so far. Only data on the behavior of AISI 316L are listed. Therefore test specimens of this Steel were exposed to selected corrosive substances in order to compare both steels.
Due to the reduced alloy content a reduced corrosion resistance of the Steel UNS S44400 in acidic substances, such as formic acid, acetic acid and sulfuric acid, in comparison to the austenitic CrNiMosteels was expected but not observed. Tests in an alkaline medium showed sufficient resistance.
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.
Materials compatibility is a major concern whenever the fuel composition is changed in a fuel system. The question arises of whether sealing materials are resistant to fuels with bioethanol and biodiesel (rapeseed oil fatty acid methyl ester).
The objective of this research was to determine the resistance of frequently used sealing materials such as FKM (fluorocarbon rubber), FVMQ (methyl-fluoro-silicone rubber), VMQ (methyl-vinyl-silicone rubber), EPDM (ethylene-propylene-diene rubber), CR (chloroprene rubber), CSM (chlorosulfonated polyethylene), IIR (butyl rubber), PA (polyamides), NBR (acrylonitrile-butadiene rubber) and PUR (polyester urethane rubber) in aged fuels and heating oil with admixtures of biogenic substances such as biodiesel and B10 (heating oil with 10% biodiesel).
The mass, tensile strength and breaking elongation of the test specimens were determined before and after exposure for 84 days in non-aged, one-year, two-year, three-year and four-year aged biodiesel and B10 according to DIN 53504 – “Testing of rubber - determination of tensile strength at break, tensile stress at yield, elongation at break and stress values in a tensile test”.
The visual examination of some elastomer test specimens clearly showed the great volume increase until breaking or partial dissolution. The Shore hardnesses A and D (for PA) were determined before and after exposure of the test specimens in the biofuels for 42 days according to DIN 53505 – “Testing of rubber – Shore A and Shore D hardness test”.
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.
Biodiesel fuels are easily oxidized and contain acids and water. 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. FKM and PA showed high compatibility in non-aged, one-year, two-year, three-year and four- year aged biodiesel, which was attributed to the absence of polarity. The decrease in tensile properties and Shore hardness increased with the age and the temperature of the biodiesel, but the measured values were still lower than the defined threshold.
FKM and FVMQ absorbed much less non-aged and aged B10 and swelled less. CR, CSM, EPDM, IIR, NBR and VMQ were not resistant to B10 at all at 20°C, 40°C and 70°C as the decrease in the tensile properties was significantly over 50%.
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 the age of the B10. The damaging impact of B10 increased with the age and the temperature.
Tanks for all seasons
(2004)
Super steels
(2002)
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.
Schuld an Korrosion
(2003)
Das Gefährdungspotential von Rohrleitungen hängt primär von den Eigenschaften des durchfließenden Stoffes, den Betriebsbedingungen und den äußeren Beanspruchungen ab. Zu den Hauptschadensursachen an Rohrleitungen zählen Korrosion, Druckstöße und Kavitationsschläge, Zeitstandbeanspruchung, struktur- und fluidmechanische Schwingungen, Fremdberührungen, elektrische Fremdbeeinflussung und geologische Besonderheiten im Bereich des Rohrleitungsverlaufes.
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.
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.
Transportation of dangerous goods are worldwide regulated in the rules or standards e.g. in the recommendations on the Transport of Dangerous Goods of the United Nations, in the Accord Européen Relatif au Transport International des Marchandises Dangereuses par Route (ADR) etc. Addi-tional to these international regulations also national regulations and stan-dards e.g. Gefahrgutverordnung Straße und Eisenbahn (GGVSE) in Ger-many are bases for the transport of hazardous materials. For the material properties of tanks in the BAM-List Requirements for Tanks for the Transport of Dangerous Goods specifications for the sub-stance prototype approval for tank materials are listed. Further compati-bility evaluations of selected metallic material groups as well as of poly-meric gasket and lining materials under the influence of dangerous goods are published in the List. There are a large number of highly corrosive dangerous goods listed, in which conventional steels are not resistant. Chemical companies, transportation providers and tank producers need tanks made of corrosion-resistant materials (corrosion retardant materi-als) in order to protect the tank shell. The application of high-alloyed stainless steels and nickel alloys as there are alloy 926 (1.4529; X1NiCrMoCuN25-20-7), alloy 31 (1.4562;X1NiCrMoCu31-27-7) and Nickel-Chromium-Molybdenum Alloy 59 (2.4605; NiCr23Mo16Al) is an al-ternative solution compared with the lining of the tanks with a polymeric material. Due to the limited number of corrosion test results with welded test sam-ples of these high-alloyed materials under the influence of corrosive dan-gerous goods BAM, Institute for Corrosion Protection (IKS) Dresden and ThyssenKrupp VDM have been performing a comprehensive test program since 2002. The program comprised corrosion resistance evaluations of the three high-alloyed materials exposed to substances representing cor-rosive dangerous goods such as inorganic halogenides, organic acidic halogenides, sulfonic acids and nitrating acids.
Pitting Prävention
(2001)
Oxidative damage of an Intermediate Bulk Container (IBC) made of polyethylene by 53 % nitric acid
(2013)
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.
Die im In- und Ausland vorliegenden Forschungsarbeiten zur Kostenabschätzung der immissionsbedingten Materialschäden beruhen auf zwei ökonomischen Bewertungsverfahren. Bewertungsgrundlage des einen Verfahrens sind die in Labor- und Freibewitterungsversuchen ermittelten physikalisch-chemischen Dosis-Wirkungs-Beziehungen zwischen dem Schadstoffgehalt der Luft und den schadensanfälligen Materialien. Die andere Methode geht von den Unterschieden im Instandsetzungverhalten in Abhängigkeit vom Standort (Industrie-, Stadt- und Landatmosphäre) der Sachgüter aus.
Daten über Schadensursachen und die tatsächliche Nutzungsdauer der Tanks zum Transport von Gefahrgütern liegen nur in begrenztem Maße vor. Auf der Basis der Daten von Tankbaufirmen, Speditionen und Eisenbahnkesselwagen-Vermietgesellschaften wurde die durchschnittliche Lebensdauer von Tankcontainern, Tankfahrzeugen und Kesselwagen zur Beförderung von Gefahrgütern in der Praxis ermittelt und die Hauptschadensursachen analysiert. Korrosion, Risse an Schweißnähten, Gestaltungs- und Dimensionierungsfehler sowie fertigungs- und betriebsbedingte Fehler zählen zu den Hauptschadensursachen. Viele Tanks werden vor Ablauf ihrer Nutzungsdauer nicht mehr für den Transport von Gefahrgütern eingesetzt, da sie nicht mehr den geänderten gesetzlichen Anforderungen in den Gefahrgutvorschriften entsprechen. Die Voraussagen durch Literaturangaben und Ergebnisse von Korrosionsversuchen in der BAM-Liste – Anforderungen an Tanks zur Beförderung gefährlicher Güter – spiegeln sich in der Nutzungsdauer/Lebensdauer der Tanks wider.
Heizöllagerbehälter aus Polyethylenformstoffen werden seit Beginn der 70-iger Jahre in Deutschland hergestellt. Die Hersteller empfehlen zur Gewährleistung der Sicherheit nach Ablauf von 30 Jahren den Ersatz dieser Behälter. Polyethylenformstoffe unterliegen im Laufe ihrer Nutzungsdauer der Alterung durch die Veränderung ihrer Eigenschaften. Das Ausmaß der Alterung und die Art des Abbauvorganges hängen im Wesentlichen vom chemischen Abbau des Polyethylens, der Wanddicke des Behälters und den Umgebungsbedingungen ab. Bisher lagen keine Untersuchungen zum Langzeitverhalten der Polyethylenformstoffe vor, insbesondere nach einer Nutzungsdauer der Tanks über 30 Jahre. Ziel der Untersu-chungen war, den tatsächlichen Schädigungsgrad der Polyethylenformstoffe im Vergleich zu den unbelasteten Formstoffen zu ermitteln. Da die BAM bis Mitte der 90-iger Jahre für die Prüfungen und Gutachten zur Zulassung dieser Behälter zuständig war, sind die Werkstoffdaten noch vorhanden.
Als Untersuchungsmethoden wurden die Bestimmung der Schmelze-Masse-Fließrate (MFR) und die Fourier-Transformation-IR-Spektroskopie (FTIR) von Tankausschnitten aus dem Bereich des Bodens, des Mantels und des Daches von 10 ausgesonderten Behältern aus den Polyethylenformstoffen A und B herangezogen. Die Messungen der MFR der Tankaus-schnitte aus diesen Bereichen zeigten Unterschiede in den Werten in Abhängigkeit vom Ge-wicht (5 kg oder 21,6 kg), welches eingesetzt wurde. Eine Abnahme der MFR-Werte wurde für die größere Anzahl der Tankwandungsausschnitte aus dem Formstoff B nach einer Lebensdauer der Tanks > 30 Jahre gemessen. Dieser Formstoff wurde hauptsächlich durch innere Alterung infolge Vernetzungen, Verzweigungen und Weichmacherverlust und weniger durch oxidativen Abbau geschädigt. Die FTIR-Messungen der Proben aus dem Bereich des Bodens und des Mantels der Tanks zeigten, dass die Intensität der asymmetrischen/symmetrischen CH2 -Streckschwingungen im Bereich: 2800 - 2900 cm-1 und der CH2 -Biegeverformungsschwingung bei 1400 cm-1 aufgrund von Kettenspaltungen zugenommen haben. Die Intensität der Carbonylstreckschwingung C=O bei 1740 cm-1 ist niedrig. Sie ist ein Maß für die Oxidation des Polymerwerkstoffes.
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.
Tanks for heating oil made of polyethylene grades have been on the market since the early 1970s in Germany. Tank manufacturers recommend the replacement of the tanks after a period of 30 years due to guarantee safety. Polyethylene grades are subject to ageing by alteration of the properties during their life cycle. 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 behavior of the polyethylene grades, especially after a service life of more than 30 years. The aim of this investigation was the determination of the factual degree of damage in comparison to the uncontaminated polyethylene grades. Material data of the used polyethylene grades are available because the BAM was the competent authority for the tests and expert reports for the approval of these tanks until the middle of the 1990s.
The determination of the Melt Flow Rate (MFR) and the Fourier Transmission IR Spectroscopy (FTIR) of tank sections from the bottom, the shell and the roof of 10 segregated heating oil storage tanks produced of polyethylene grades A and B were used as tests methods.
The MFR measurements of the tank sections showed differences in the values depending on the weight which was used (5 kg or 21.6 kg). A reduction of the MFR values was measured for most of the sections of tanks made of polyethylene grade B after a service life of the tanks of more than 30 years. This grade is mainly subject to the internal ageing by cross-linkages, increased degree of branched molecules and loss of the plasticizer, and to a lesser extent by oxidative degradation. The FTIR analysis, especially of tank sections of the bottom and the shell showed that the intensity of the CH2 asymmetric and symmetric stretching vibrations in the range: 2800 - 2900 cm-1 and the CH2 bending deformation vibration at 1400 cm-1 increased due chain scissions. The intensity of the carbonyl stretching vibration C=O at 1740 cm-1 is low. The carbonyl index characterizes the degree of oxidation.
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.
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.
Materials compatibility is a major concern whenever the fuel composition is changed. The question arises of whether sealing materials are resistant to fuels with bioethanol and biodiesel (rapeseed oil fatty acid methyl ester).
Previous research considered the resistance of frequently used sealing materials such as FKM (fluorocarbon rubber), FVMQ (methyl-fluoro-silicone rubber), VMQ (methyl-vinyl-silicone rubber), EPDM (ethylene-propylene-diene rubber), CR (chloroprene rubber), CSM (chlorosulfonated polyethylene), IIR (butyl rubber), PA (polyamides), NBR (acrylonitrile-butadiene rubber) and PUR (polyester urethane rubber) in fuels and heating oil with admixtures of biogenic substances such as biodiesel and B10 (heating oil with 10 % biodiesel) under purely static conditions.
The aim of this study was to evaluate the fluorocarbon rubber performance under compressed conditions. For the investigations, the mass and the compression set of the FKM test specimens were determined before and after exposure for 3, 7, 14, 28, 56 and 90 days in E10 (fuel with 10 % ethanol), E85 (fuel with 85 % ethanol), biodiesel (fatty acid methyl ester, FAME), Super (fuel with max. 5 % ethanol), diesel fuel with max. 5 % biodiesel, pure diesel fuel, Super Plus (fuel without ethanol) and heating oil with 10 % biodiesel (B10) at 40 °C according to ISO 815-1 “Rubber, vulcanized or thermoplastic - determination of compression set – Part 1: At ambient or elevated temperatures”. The compression set test belongs beside the determination of the Shore hardness, the density and the tensile properties to the basic test methods for elastomers. It was measured in regular time intervals up to a re-drying of more than 90 days after relaxation of test specimens. For comparison, FKM test specimens were exposed without fuel under compressed conditions at 40 °C.
The highest mass increase of FKM test specimens was measured after 90 days exposure in E10 by 9 %, followed by 8 % in Super fuel, by 4 % in E85 and by 0.6 % in biodiesel. Mass increase and swelling of the test specimens in E10 and Super fuel with max. 5 % ethanol had an influence on the compression set values which were subject to high fluctuations in comparison to the values obtained after exposure to other fuels such as biodiesel, diesel fuel and B10.
The results of the present work confirmed the higher swelling of the elastomers such as FKM in E10 obtained under static condition. It can be concluded on the basis of the mass increase and compression set values that FKM is resistant in all fuels under compressed conditions at 40 °C.
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.
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.
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.