Abstract
The corrosion rate is generally measured using intrusive technologies such as coupons and electrical resistance probes. Field trials were carried out to detect flow characteristics (e.g. type of flow, liquid film height) and subsequent corrosion in hilly terrain pipelines using high-precision, non-intrusive ultrasound techniques. The ultrasound corrosion monitor was based on very fast response data collection, signal identification, and signal analysis. A cross-correlation, pulse-echo technique was used for the measurement of multiphase flow characteristics.
The field pipeline was examined for changes of inclination since the topography of the pipeline in multiphase flow can seriously affect the flow conditions. There were significant levels of bicarbonate ions in some lines which affected the pH significantly. The pH ranged between 4.0 and 6.0 depending on the temperature, pressure and the bicarbonate.
It was seen from the measurements of the localized flow that the corrosion rate calculated using these values was in good agreement with the measured corrosion rates.
This paper describes the flow and corrosion measurements carried out on several flowlines. The localized flow and corrosion is identified and methods for the corrosion rate prediction are suggested.
