High temperature MIC on an offshore pipeline and the strong arsenate-reduction function in the hyperthermophiles

• The high temperature MIC on an offshore pipeline (105 °C) has been studied.
• The four different types of biofilms of the hyperthermophiles have been discovered.
• The microscopic bio-tubercles and bio-spherical particles have been found.
• The multi-metal and sulphate-reduction functions of the hyperthermophiles have been studied.

Hyperthermophiles are microorganisms that can thrive at high temperatures (80–122 °C). This article presents the study of hyperthermophilic influenced corrosion on an offshore pipeline (105 °C). Research with material science-based approaches found the multi-metal and sulphate reduction functions in the hyperthermophiles. ESEM/EDS (environmental scanning electron microscopy/energy-dispersive spectroscopy) analysis discovered different types of biofilms, microscopic bio-tubercles and bio-spherical particles. All of these findings confirm the MIC. There were two corrosion modes inside the pipe, uniform corrosion and localised severe corrosion. The localised severe pitting only occurred around the weld, suggesting the nitriding effect could attract the hyperthermophiles to proliferate. In the uniform corrosion, there were three layers in the cross section of the bio-oxide scale. In the middle layer, up to 38.94% of arsenic had been detected, indicating the strong arsenate-reduction capability.