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Die Schwingungsrisskorrosionsbestandigkeit zweier Stahle (Superaustenit (1.3974) und ein Duplexstahl (1.4462)) wurde anhand von Zugschwell-, Umlaufbiege-, Scheiteldruckschwell- und Innendruckschwellversuchen vergleichend untersucht. Die Untersuchungen wurden in 10 % Salpetersaure, in kunstlichem Meerwasser nach DIN 50905 und in den beiden fur die Praxis besonders relevanten Medien Kaliumjodidlosung und H2S-begastem kunstlichen Meerwasser nach DIN 50905 und zum Vergleich in saurefreiem Spindelol durchgefuhrt. Die Ergebnisse belegen, dass der Werkstoff 1.3974 unter ein- und dreiachsiger Beanspruchung bis 107 Schwingspiele eine deutlich hohere Schwingungsrisskorrosionsbestandigkeit als der Werkstoff 1.4462 aufweist. Es wurde ein Korrosionsfaktor ermittelt, der das Verhaltnis aus den Versuchen in den korrosiven Medien im Vergleich zu den Ergebnissen in saurefreiem Spindelol beschreibt. In kunstlichem Meerwasser nach DIN 50905 ergibt sich ein Faktor zwischen 0,67 und 0,92 in Abhangigkeit der Beanspruchung fur den Werkstoff 1.4462. In 10 % Salpetersaure ergibt sich fur den Werkstoff 1.4462 ein Faktor zwischen 0,67 und 0,83. Beim Werkstoff 1.3974 wird ein Faktor von 0,86-1 in kunstlichem Meerwasser nach DIN 50905 und von 0,70-1,0 in 10 % Salpetersaure ermittelt. Rust and acid resistant steels under complex loading With corrosion fatigue investigations under different loadings (R = 0,27, -1 and 10) and with inner pressure tests a duplex steel (1.4462) and a super austenitic steel (1.3974) are compared. The investigations were carried out in 10 % HNO3, artificial seawater according to DIN 50905 and in two very important liquids for application (artificial seawater according to DIN 50905 with H2S aerated and water with chloride, fluoride, bromide, iodide). For comparison the same tests under only mechanical loads were done in acid free oil. The results show that the super austenitic steel has an significantly higher resistance against corrosion fatigue as the duplex steel under one- and three dimensional loads up to 107 cycles. The proportion between the results in the corrosive liquids and the oil can be described by a factor. In artificial seawater factors between 0,67 and 0,92 and in 10 % HNO3 between 0,67 and 0,83 were determined depending from the loading for the duplex steel. With the super austenitic steel factors between 0,86 and 1 in artificial seawater and between 0,7 and 1,0 in 10 % HNO3 were received.

Supercritical extraction plants require high pressure pumps. Diaphragm pumps have the advantages of providing sealless design, low maintenance, zero leakage, and no contamination of the process fluid. This paper reports on new developments in the hydraulic control and diaphragm design in metal and plastomer (PFTE and others) materials, with special attention given to sealing and fatigue. A thermodynamic model for the prediction of the pump's volumetric efficiency under various conditions is also proposed and design guidelines are evaluated. The model yields a prediction of the necessary suction conditions to avoid cavitation.

Publisher Summary This chapter focuses on the endurance prediction of thick-walled high pressure components under corrosion fatigue conditions. The corrosion fatigue data from uniaxial tests can be transmitted to the notched pulsating pressure loaded components quantitatively or with additional safety. The uniaxial pulsating stress yields to be the stricter criterion. Differences in the correlation of the corrosion fatigue reduction data can be attributed to the residual stresses because of local plastification. The steel 1.4462 seems to develop more autogeneous autofrettage because of the lower strength. Fatigue ruptures start with the uniaxial probes at any flaws with the pipe probes very near to the cross-bore intersection. If failures have already occurred, the improved material choice yields from uniaxial fatigue tests with the real liquid involved. For initial design purposes of thick-walled components, uniaxial corrosion fatigue data can directly be applied. If the operational conditions or the component treatment involve autofrettage, the application of corrosion fatigue data implements an additional safety factor. Applications for current failure analysis demonstrate the efficiency of the method.