PR405-163602-R01 Evaluation of AC Corrosion Coupons for Monitoring Applications

This report refers to the activities performed in the frame of a PRCI project on evaluation of AC coupons for monitoring applications. AC coupons are aimed to take decisions on whether the subjected pipeline is at AC corrosion risk and if additional mitigative measures need to be undertaken to reduce the AC induced voltage on the pipeline.

As a variety of coupons exist on the market with different dimensions, configuration and shape, the AC current density response of the coupons was investigated. A market search was performed to identify the commercial available coupons. A screening of the coupons was performed by:

– simulating the AC current density response in a 3D computational model;

– laboratory testing of retained coupons and probes under different soil moisture conditions;

– field testing of AC coupon behavior

The AC current density response of a total of 20 coupons/ probes from different vendors have been simulated and ordered according to increasing average current response and local peak current at the edges. Consequently 7 coupons/probes were retained for laboratory testing in sand and clay soil with different moisture content. Finally one commercial coupon and two new designs of ER probes were installed at two different sites along a pipeline for field testing and monitoring.