Cathodic protection coupons are a simple, size-specific piece of metal with one or more wires attached and are used for evaluating corrosion control or cathodic protection systems protecting a structure, typically a steel pipeline. These measurements include:
- Native or unprotected structure-to-soil potentials
- Structure-to-soil potentials with the CP system energized
- Structure-to-soil potentials with the CP system interrupted
- To emulate an “OFF” structure-to-soil potential without interrupting CP current, typically referred to as a “Coupon Interrupt” reading
- For magnitude measurements of AC current density on a structure with known induced AC issues
A new design, the "Hemi-10" steel C.P. coupon is a 10 cm2 half-round coupon designed for maximum contact to earth, which is critically important for AC current density measurements.
The 10 cm² coupon allows better contact to native earth as compared to the smaller 1 cm² coupons. For AC current density measurements, the 10 cm² surface area allows a direct conversion from mA to A/m² without having to use any mathematical conversions.
The coupon is mounted inside a durable PVC housing and the Hemi-10 is provided with a single or dual length of #12 AWG stranded copper cable with RHH/RHW direct burial insulation, typically green in color.