Yanxia Du

Electrochemical Studies on the Performance of Zinc Used for Alternating Current Mitigation

In this work, the performance of zinc under alternating current (AC) with a decoupler was investigated in 4 g/L Na2SO4 simulated backfill solution by weight loss tests, electrochemical measurements, scanning electron microscope analyses, and x-ray diffraction examination. The results showed that zinc corrosion was accelerated under AC. As a result of the effects of AC, the corrosion product film deposited on the zinc surface increased first and then was destroyed gradually by AC oscillation. The ratio (AC current efficiency) of weight loss caused by AC to that caused by an equivalent steady-state direct current density was calculated. The results indicated that AC current efficiency was no more than 1.7% at AC current density of less than 300 A/m2 and it reduced with the decrease of AC current density.

Investigation on corrosion of zinc ribbon under alternating current

Abstract Zinc ribbon has been widely used for alternating current (ac) mitigation of pipeline. However, little is known about corrosion of zinc under ac. In this work, the corrosions of zinc under various ac in two scenarios, i.e. with or without direct current (dc) decoupler, were investigated in 4 g L− 1 Na2SO4 simulated backfill solution by weight loss tests, low angle X-ray diffraction measurements and electrochemical measurements. It was found that ac accelerated corrosion of zinc dramatically in both scenarios, and it is worth noting that dc density between zinc and pipeline steel increased with ac in the scenario without dc decoupler. Consequently, corrosion rate of zinc was much larger than that in the scenario in which dc decoupler was used. Besides, the charge transfer resistance of zinc decreased considerably due to ac in both scenarios, which would largely increase corrosion rate.

Detection and Mitigation of AC Interference on 200km Pipeline

The AC interference on pipelines caused by nearby HVAC power lines and electrified railways can lead to electric shock hazard and AC corrosion, which threatens the safety of pipeline and has attracted more and more attention. A 300km-long pipeline in the north of China is close to many HVAC power lines and electrified railways and there exists a high risk of AC interference. A detection of AC interference has been done along the pipeline and the results indicate that AC interference is severe due to high AC voltage and AC current density. The mitigation scheme of the pipeline is designed with the aid of computer simulation software, based on which the mitigations are constructed. The field measurements show that the mitigation effect is good.Copyright