Coupon

The test coupon is the "standard sample" for evaluating cathodic protection effectiveness. It uses metal coupons of the same material as the protected structure, buried in the same corrosive environment as the pipeline; by periodic weighing or coupling with a reference electrode to measure potential / polarization, it quantitatively evaluates whether CP meets the criterion and the actual corrosion rate. It is widely used in long-distance pipelines, oil storage tanks, offshore platforms, underground networks and other CP systems for effectiveness verification.

Key Technical Specifications

• MaterialSame as pipeline (Q235 / X60 / X70 / X80, customizable)
• Standard dimensions100 × 50 × 3 mm / 50 × 25 × 3 mm (customizable)
• Exposed surface area≈ 100 cm² (100 × 50, double-sided)
• Lead wireInsulated anti-corrosion cable, 3 m / 5 m / 10 m
• Reference electrodeCu/CuSO₄ or Ag/AgCl (for polarized coupon)
• Measured parametersNatural potential, instant-off potential, polarization potential, weight-loss corrosion rate
• Operating temperature-40 °C to +70 °C
• SealingWaterproof sealed connector, IP68 (long-term burial)
• MountingCo-laid in pipeline trench / inside test post / dedicated protective tube
• Applicable mediaSoil, fresh water, seawater & various corrosive environments

Key Features & Advantages

• Same material & same environment, real data: same metal and burial depth as the structure, reflects real corrosion status rather than theoretical estimate.
• Quantitative evaluation, intuitive & reliable: weight-loss method directly gives corrosion rate (mm/a), compensating the bias of pure potential judgment.
• Online & offline combined: polarized coupons measure potential online; weight-loss coupons verify offline — complementary and cross-checked.
• Verifies protection criteria: confirms whether the instant-off potential / polarization meets criteria such as -850 mV.