Cathodic protection test devices should be installed simultaneously with the cathodic protection system. Test devices should be arranged along the pipeline route, with the spacing between adjacent test devices preferably not exceeding 3 km. In urban or industrial areas, the spacing between adjacent test devices should not exceed 1 km; in areas affected by stray current interference, test devices may be appropriately increased in density. Test devices should be installed above the pipeline and marked. Intelligent test stakes should monitor the following parameters: DC pipe-to-soil potential, coupon off-potential, coupon current; AC voltage, AC current. The area of the DC potential coupon should be 6.5–10 cm2, and the area of the AC coupon should be 1.0 cm2.
For regional cathodic protection at stations, it is not recommended to install test stakes; instead, reference electrodes should be buried at locations where pipe-to-soil potential measurements are needed to facilitate the placement of portable reference electrodes. Any above-ground metal can serve as a contact point for the red probe during measurements. Since the pipelines within the entire station are interconnected and form an equipotential body, connecting to any structure within the station will not affect the potential reading.
(1) Test devices should be installed at the following locations:
① Insulating joints;
② Metal casing locations;
③ Coupon and drainage grounding device connection points;
④ Auxiliary anode and sacrificial anode installation points;
⑤ Pipeline directional drilling crossing points.
(2) Intelligent test stakes should be installed at the following locations:
① Pipeline feature discontinuities (elbows, high-voltage line phase changes, turning points);
② Locations with low soil resistivity;
③ Cathodic protection station current drainage points and midpoints of cathodic protection stations;
④ Locations with DC interference.
(3) Other considerations:
① Install potential coupons every 5–10 km along the pipeline;
② When metal casings have high-quality coatings, leave 2 m of exposed sections at both ends of the casing;
③ Ensure electrical continuity between valve room instruments and the valve body, with the valve body connected to the grounding grid via lightning arresters or DC decouplers;
④ Install surge protection devices at all insulating isolation points.
Intelligent cathodic protection test stakes are a new product of IoT information technology. Traditional test stakes previously required manual on-site measurements, primarily collecting cathodic protection potentials of pipelines, which not only resulted in low work efficiency but also low data accuracy. Data collection was significantly affected by environmental factors, and data reporting and statistics were cumbersome. To align with the trend of intelligent development in pipeline cathodic protection, our company has independently developed a new type of intelligent test stake. These test stakes utilize new along-line technology, enabling the collection of cathodic protection data to be diverse, automated, intelligent, and remote. This greatly improves the work efficiency and safety of pipeline cathodic protection maintenance personnel.
The new intelligent cathodic protection test stakes can not only automatically measure cathodic protection data such as pipeline cathodic protection potential, natural potential, and off-potential but also detect interference data from stray currents on the pipeline, such as AC induced voltage and AC stray current density. This facilitates thorough elimination of stray current interference on the pipeline by management personnel and provides comprehensive data monitoring functions for the stable operation of the pipeline.
Intelligent test stakes, in combination with buried long-life reference electrodes and chemical coupons, enable the collection of data such as pipeline on-potential, free corrosion potential, off-potential, AC interference voltage, and AC stray current. The data is converted into binary data recognizable by computers through the device's high-precision operational amplifier circuit and A/D analog-to-digital conversion circuit. After processing, packaging, and transcoding by the CPU, the data is sent to the server via an onboard 4G communication module, where it is parsed and stored. Customers only need to log in to the B/S architecture software page using a browser to view the cathodic protection data from various pipeline tests.
Traditional test stakes primarily rely on manual field measurements using instruments such as multimeters for cathodic protection data detection. This method results in single data collection, low efficiency, poor reliability, and high risk, making it difficult to meet the growing demand for cathodic protection data monitoring of long-distance pipelines.
Intelligent cathodic protection test stakes can effectively reduce the human and material resources invested in monitoring the cathodic protection effectiveness of long-distance pipelines while improving the timeliness and reliability of data transmission. They also lower the management, operation, and maintenance costs of the cathodic protection system, enabling integrity management and multi-method monitoring of key high-risk areas. This facilitates early warning detection, prevents accidents, and enhances the intelligent management level of the cathodic protection system.