Experimental study on pipeline internal corrosion based on a new kind of electrical resistance sensor

• The principle of ring pair electrical resistance sensor (RPERS) is described.
• Temperature difference and localized corrosion monitoring can be realized.
• The measurement accuracy of RPERS is higher than traditional ER sensors.
• The relationship between the gas temperature and corrosion rates is studied.

In this paper, a ring pair electrical resistance sensor (RPERS) has been developed for an internal-pipeline corrosion on-line monitoring system. The RPERS was divided into six segments along the circumference. The corrosion depth of each segment could be measured by using three alternating excitation currents injected into the sensor from different angles. In order to simulate and monitor the pipeline internal corrosion, a corrosion monitoring system which contained RPERS, wire electrical resistance sensor (WERS), thermocouples and a corrosion coupon was established. First, the corrosion processes in 3.5% sodium chloride solution with the temperature varied from 30 °C to 60 °C were studied. The temperature differences between the inner and outer pipe wall surfaces were measured by the top segment of RPERS. The test results revealed that the performance of RPERS is better than that of WERS in term of metal loss measurement. Then, carbon dioxide mixed with water vapour was pumped into the system with the temperature varied from 50 °C to 80 °C. In the scenarios, top of the line corrosion (TLC) occurred and was monitored by RPERS. The monitoring results demonstrated that the gas temperature and the temperature difference were important factors for TLC in sweet conditions.