TY - THES

T1 - Characterization of the Rapid Gas Decompression Behavior of HNBR Based Rubber

AU - Schrittesser, Bernd Christian

N1 - embargoed until null

PY - 2010

Y1 - 2010

N2 - Seals and hoses for oilfield application are exposed to high temperatures, aggressive fluids and various gases. A specific failure, the rapid gas decompression failure, can occur during the exposure to high pressure and various gases. This failure results in a crack growth, extensive deformation, swelling, blisters and in some cases catastrophic fragmentation of the vulcanised rubber. The aim of this thesis was to provide additional information on the rapid gas decompression failure. This is relevant, because of the unique thermal and mechanical properties as a result of the penetration of the ambient gas. According to several engineering standards, unconstrained and constrained measurements are common (NACE and NORSOK). In these standards the failure interpretation is solely based on the visual observation after the test. Therefore, additional measurements are necessary to understand the material performance during the exposure to high pressure gas. In a first step in a former thesis a camera system was implemented in order to observe the volume change during the test procedure. In this thesis this test setup was adapted for in situ constrained tests and the measurement of uniaxial expansion forces in the tested materials. Four hydrogenated nitrile butadiene formulations with different acrylonitrile content and fillers were investigated. Based on the recorded measurements a clear correlation between unconstrained and constrained measurements was found. To characterize the filler dependent behaviour and to investigate the influence of the rising acrylonitrile content a filler factor and an acrylonitrile factor were defined. A clear effect of ACN and filler content was found in both test setups. In particular, different incubation times were observed for the volume change and force increase during depressurization. Additional tests, including relaxation test, dynamic mechanical analysis, thermal conductivity and expansion measurements were carried out to supply fundamental material properties. The temperature-dependent storage modulus seems to influence the investigated volume increase during depressurization. With rising storage modulus the volume change drops and vice versa.

AB - Seals and hoses for oilfield application are exposed to high temperatures, aggressive fluids and various gases. A specific failure, the rapid gas decompression failure, can occur during the exposure to high pressure and various gases. This failure results in a crack growth, extensive deformation, swelling, blisters and in some cases catastrophic fragmentation of the vulcanised rubber. The aim of this thesis was to provide additional information on the rapid gas decompression failure. This is relevant, because of the unique thermal and mechanical properties as a result of the penetration of the ambient gas. According to several engineering standards, unconstrained and constrained measurements are common (NACE and NORSOK). In these standards the failure interpretation is solely based on the visual observation after the test. Therefore, additional measurements are necessary to understand the material performance during the exposure to high pressure gas. In a first step in a former thesis a camera system was implemented in order to observe the volume change during the test procedure. In this thesis this test setup was adapted for in situ constrained tests and the measurement of uniaxial expansion forces in the tested materials. Four hydrogenated nitrile butadiene formulations with different acrylonitrile content and fillers were investigated. Based on the recorded measurements a clear correlation between unconstrained and constrained measurements was found. To characterize the filler dependent behaviour and to investigate the influence of the rising acrylonitrile content a filler factor and an acrylonitrile factor were defined. A clear effect of ACN and filler content was found in both test setups. In particular, different incubation times were observed for the volume change and force increase during depressurization. Additional tests, including relaxation test, dynamic mechanical analysis, thermal conductivity and expansion measurements were carried out to supply fundamental material properties. The temperature-dependent storage modulus seems to influence the investigated volume increase during depressurization. With rising storage modulus the volume change drops and vice versa.

KW - Rapid Gas Decompression Explosive Decompression Gas induzierter Bruch Gas induzierte Volumenzunahme Gas-Transport in Elastomere Druckentlastung

KW - rapid gas decompression explosive decompression gas induced rupture gas induced swelling gas transport in elastomers depressurization

M3 - Master's Thesis

ER -