For buried pipeline cathodic protection systems, the ohmic voltage drop caused by the cathodic protection current on the soil resistance introduces significant errors in the online measurement of pipe-to-soil potential. This has a substantial impact on the accurate evaluation of the effectiveness of cathodic protection. The use of the current interrupt method can effectively eliminate this IR drop. However, as mentioned earlier, simply applying the current interrupt method does not resolve the influence of the IR drop caused by the balancing current between different damage points on the coating.

Cathodic protection test coupons, or polarization coupons, adopt a cylindrical coupon structure. The coupon area is determined by adjusting both the diameter and the exposed height L. They can be used as polarization coupons or AC coupons, among other applications, for measuring the cathodic protection interrupt potential or AC current density.
Performance parameters of cathodic protection test coupons (polarization coupons):
Coupon material: Carbon steel (can be customized according to pipeline steel material)
Cable length: 5 m (customizable)
Exposed area of coupon: 1 cm2, 6.5 cm2, 10 cm2, and other custom sizes

The configuration and operation of the polarization coupon method are similar to those of test coupons in pipeline cathodic protection systems. A bare coupon is buried at a selected test point location, with material and burial conditions identical to those of the protected pipeline. The soil environment at the coupon burial site should be consistent with that of the pipeline. The exposed area of the polarization coupon should be determined during design and strictly controlled. The exposed area of the coupon essentially simulates the size of a coating damage point. When the coupon is connected to the protected pipeline via a test lead through a test station, it becomes a leakage point for the protection current, much like a coating damage point. Therefore, excessive polarization coupons should not be installed along the pipeline to avoid excessive loss of protection current. When burying polarization coupons, a long-term fixed reference electrode should also be buried nearby for potential measurement. During installation, care must be taken to avoid inducing current effects on the connected coupon.

Henan Bangxing Anticorrosion Materials Co., Ltd. offers products spanning five major series, including sacrificial anodes, lightning protection and grounding, thermite welding, explosion-proof electrical equipment, and related supporting products, with over 300 varieties. The company holds multiple national utility model patents. Key products include: magnesium alloy anodes, zinc alloy anodes, aluminum alloy anodes, cathodic protection test stations, zinc and magnesium ribbons, high-silicon cast iron anodes, deep well anodes, MMO flexible anodes, potentiostats, solid-state decouplers, spark gaps, equipotential bonding devices, explosion-proof junction boxes, explosion-proof distribution cabinets, intelligent potential collectors, potential transmitters, lightning protection and grounding materials, copper-clad steel strands, copper sulfate reference electrodes, high-purity zinc reference electrodes, polarization probes, zinc grounding cells, thermite welding, heat-shrink sleeves, repair materials, balance weight bags, pipeline sliders, titanium conductive sheets, insulating joints, lifting rods, and a full range of cathodic protection and supporting products.