Induced material degradation of elastomers in harsh environments

Abstract

The elastomeric components used in oil drilling operations, especially sealing solutions, are experiencing hardships from high pressure, high temperature and in contact with fluids. Therefore, the present work contributes to identifying the behaviour of hydrogenated nitrile butadiene rubber (HNBR) in contact with solvents and gases, and the ageing effect on resistance to rapid gas decompression (RGD). The swelling behaviour of HNBR was measured in different solvents and the tensile properties in different swollen conditions, i.e., un-swollen, swollen and de-swollen, were tested. RGD resistance was investigated in virgin and aged conditions. Deteriorated properties were observed in swollen states and the degradation magnitude was correlated with the degree of swelling; in fully de-swollen states, the un-swollen properties were regained. In RGD measurements, a relatively lower gas permeation was seen in swollen samples as well as the lowest volume increase during the decompression phase. However, crack observation based NORSOK ranking rates the RGD resistance in thermo-oxidative aged HNBR to be best followed by swollen and virgin samples, respectively.