Membrane-based electrochemical sensors (MBES) provide an attractive option for real-time continuous
humidity and corrosion rate measurements inside of natural gas pipelines. The MBES can use
electrochemical techniques such as linear polarization resistance and electrochemical impedance
spectroscopy even when a conductive aqueous phase is intermittent or unavailable. We now present
field-test performance data of our MBES operated inside a multiphase liquid water and natural gas flow
facility. The MBES measured internal corrosion and conductivity at the top, bottom, and side of the pipe
spool. Tests were carried out with flow rates of 4.6, 9.1, and 18.3 m/s, temperatures of 21, 29, and 35
°C, and a pressure of 1000 psia. All sensors followed similar trends in open circuit potential, corrosion
rate, and conductivity over time. Neither flow rate, temperature, nor build-up of metal-based solids on the
sensor surfaces impacted the quality of the electrochemical measurements. The field-test results confirm
that the membrane-based electrochemical sensors are suitable for monitoring internal corrosion of
operational natural-gas pipelines.