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Erscheinungsjahr
- 2014 (12) (entfernen)
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Schlagworte
- Dangerous goods (3)
- Biofuels (2)
- Change in tensile properties (2)
- Compatibility (2)
- Duplexsteel (2)
- Mass loss (2)
- Sealing materials (2)
- Austenitic CrNiMo steel (1)
- B10 (1)
- BAM-list (1)
Eingeladener Vortrag
- nein (6)
Biofuels including ethanol and biodiesel (fatty acid methyl ester) represent an important renewable fuel alternative to petroleum-derived transport fuels. Increasing biofuel use would bring some benefits, such as a reduction in oil demands and greenhouse gas emissions, and an improvement in air quality.
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 aim of this work is to study the interaction between sealing materials such as FKM (fluorocarbon rubber), EPDM (ethylene-propylene-diene rubber), CR (chloroprene rubber), CSM (chlorosulfonated polyethylene), NBR (acrylonitrile-butadiene rubber), IIR (butyl rubber), VMQ (methyl-vinyl-silicone rubber), FVMQ (methyl-fluoro-silicone rubber) and PA (polyamide) and biofuels such as biodiesel (FAME, non-aged and 2 years aged), E85 (fuel with 85% ethanol) and B10 (heating oil with 10% biodiesel, non-aged and one year aged) compared with premium-grade fuel at 20°C, 40°C and 70°C for 84 days. Exposure experiments were conducted with specimens of these elastomers to document the changes in the mass and tensile properties of these sealing materials. Visual examination of some test specimens clearly showed a great volume increase until breakage or partial dissolution.
The sealing materials FVMQ, VMQ and PA were evaluated as resistant in E85 at 20°C and 40°C with a reduction of tensile properties limited to 15%. None of the examined materials was evaluated as resistant at 70°C with even fluorocarbon rubber losing 20% of its tensile strength in E85.
When exposed to biodiesel, elastomers were affected in two ways: firstly, by absorption of liquid by the elastomers and, secondly, by dissolution of soluble components from the elastomers into the liquid medium. Swelling was the result of the high absorption by the elastomers CR, CSM, EPDM, IIR and NBR in comparison to their dis-solution in non-aged and two years aged biodiesel. FKM, VMQ and PA were evaluated as resistant sealing materials in non-aged biodiesel at 40°C. FKM was still resistant in aged biodiesel at 40°C but only to a limited degree at 70°C.
The sealing materials CR, CSM, EPDM, IIR, NBR and VMQ were damaged to a high extent in non-aged and one year aged B10 as a result of swelling up to 70°C. FVMQ and PA can be evaluated as resistant in non-aged and one year aged B10 at 20°C and 40°C. However, FKM was evaluated as resistant up to 70°C.
The exposure tests showed that all the elastomers tested were resistant in the premium-grade fuel Super at 20°C. On increasing the temperature to 40°C, only FKM, VMQ and PA were resistant to Super. At 70°C FKM showed the best resistance.
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 BAM - 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 7000 dangerous goods have been published in the BAM-List since 1989.
The duplex Steel 1.4362 (2304, UNS S32304) was originally developed as substitute for the austenitic grades 1.4404 (316L, UNS S31603) and 1.4571 (316Ti, UNS S31635). Due to its characteristic profile this Steel was qualified for applications requiring high strength values at concomitant adequate corrosion resistance. Because of its lower content of the alloy elements nickel and molybdenum this duplex Steel is a cost-efficient alternative to the molybdenum containing austenite. Only a limited number of corrosion test results of 1.4362 under the influence of dangerous goods published in the BAM-List were available. Therefore test specimens of this Steel were exposed to selected corrosive substances.
Due to the reduced alloy content a reduced corrosion resistance of the duplex Steel 1.4362 in acidic substances, such as formic acid, acetic acid and sulfuric acid, in comparison to the austenitic CrNiMosteels was observed. Tests in the alkaline medium showed a sufficient resistance.
In der DIN 6601 - Beständigkeit der Werkstoffe von Behältern/Tanks aus Stahl gegenüber Flüssigkeiten (Positiv-Flüssigkeitsliste) ist die Beständigkeit unlegierter Stähle, austenitischer CrNi- und CrNiMo-Stähle gegenüber den reinen Ottokraftstoffen bewertet. Mit der verstärkten Verwendung bioethanol- und biodieselhaltiger Kraftstoffe und Heizöl stellt sich auch die Frage nach der Beständigkeit der handelsüblichen Tank- und Behälterwerkstoffe sowie der Dichtungswerkstoffe unter dem Einfluss dieser Medien.