Impressed current cathodic protection technology for shallow buried anode ground bed

1、 Classification of shallow buried positive polar beds

（1） According to the construction method, the shallow buried anode can be divided into:

1. Horizontal embedding: generally in the depth of 3000-10000mm;

2. Vertical embedding: the diameter is generally between 400 mm and 800mm;

3. Laying of ground bed: cable trench is generally used, the depth is generally below the frozen soil layer, and flexible anode is mainly used.

（2） According to the circuit, the shallow buried anode is divided into:

1. Current loop: in this circuit, the positive pole of DC power supply is connected with the auxiliary anode, and the negative pole is connected with the protected object to output current to the protected metal, that is, cathodic protection current anode bed → cable → ammeter ← cable ← protected object ← soil (water);

2. Potential circuit: a long-term reference electrode is set in the environmental medium. The protective potential of the protected metal can be detected and controlled by the voltmeter of the detection device. The potential signal of the structure is fed to the monitoring station or potentiostat, and the output current of the DC power supply can be adjusted manually or automatically, so as to reach the regulation The purpose of the protection scope is to protect the object → cable → detection device (voltmeter) ← cable ← reference electrode ← soil (water).

（3） Auxiliary anodes are classified from materials

1. Steel anode;

2. High silicon cast iron anode;

3. Graphite anode;

4. Lead alloy anode;

5. Magnetic iron oxide anode;

6. Platinum and platinum plated anode;

7. Flexible anode;

8. Noble metal oxide anode.


2、 The role of shallow buried anode earth bed

Shallow buried anode ground bed, namely auxiliary anode ground bed, is the basic component of cathodic protection impressed current system to form a complete current loop. The shallow buried anode ground bed of impressed current cathodic protection system is actually an electrolytic cell, and the auxiliary anode is the anode of the electrolytic battery. The main features of auxiliary anode are as follows:

1. Long life and reliable current bearing;

2. Supply and distribute current to the protected structure;

3. It has good conductivity;

4. The junction resistance of anode in electrolyte environment is low;

5. The anode polarizability is small and can pass through the maximum flow rate;

6. Good chemical stability, corrosion resistance, low consumption rate, less autolysis and long service life;

7. It has certain mechanical strength, corrosion resistance, impact, vibration and high reliability;

8. Good processability, easy to be made into various shapes;

9. Materials are widely available and cheap.


3、 Installation and precautions of shallow buried anode earth bed

1. Fill enough conductive filler coke around the auxiliary anode;

2. Correct selection of anode ground bed position can reduce anode grounding resistance, anode consumption, operation cost, interference prevention, and ensure the effectiveness of cathodic protection system, which is convenient for construction;

3. The location of anode ground bed, the place with high groundwater level or low humidity, and the place with soil resistivity less than 50 Ω. M has thick soil layer, which is convenient for construction.

4、 Maintenance of shallow buried anode earth bed

The grounding resistance of shallow buried anode needs to be tested regularly, and the pollution-free water should be watered every half a year to achieve better results with better maintenance.