Flexible Anode Cathodic Protection Technology


Flexible anode can be classified in to two categories: linear anode based on the nano conductive carbon black composite technology and linear anode based on MMO/Ti coating. Both products are used for impressed current cathodic protection of buried structures, such as buried oil (gas) pipelines, underground tank, petrochemical container etc. in order to slow down corrosion. The flexible anode is characterized by easy installation, completed supporting facilities and reasonable price.


Application include: 1. Coating aging old pipelines 2. Pipe network 3. Storage tanks 4. long distance, small pitch parallel pipeline 5. High resistivity environment.


Flexible anode also called linear anode, is mainly solves problems on cathodic protection of coating aging old pipelines, now it’s widely used in cathodic protection of pipes and tanks, include oil and gas transmission pipeline, oil storage tank bottom, city gas pipeline and sewage conveying pipeline, also widely used in metallurgy, water treatment industries. In the normal working current range, working life can reach more than 25years.


After 5years technical upgrade and reform work, a new conducting polymer for flexible anode is developed and obtained the patent (No.: 20091035969.9). The performance is passed the function testing of NATIONAL QUALITY SUPERVISION AND TESTING CENTER for electric wire and cable, the technical parameters can meet the flexible anode standard. We have the full product line of flexible anode, include carbon powder filling line.


Flexible Anode Based On Special Nano Conductive Carbon Black Polymer Composite(ELPA series)


This kind of flexible anode is made by new functional polymeric materials, is buried type auxiliary anodes used by impressed current cathodic protection. The polymer flexible anode’s shaped like cable, use stranded copper wire to be the conductor, covered the conducting polymer, both played release current, and also played the role of chemical corrosion resistant. Copper cored ensures the low resistance, and conduction polymer ensures the high resistance to connect the ground, to make the copper core current can get into ground step by step.


In order to form the uniform electric field, fill with carbon breeze around flexible anode can improve anode working environment, reduce the earth resistance, to extend anode life. Conductivity of conductive polymer and corrosion resistance are the two most important characteristic, also a very important criterion for normal operation and life length. We can through the testing of volume resistivity and electrolytic strengthening life to control these two parameters. We also obtain the patent of conductive polymer (patent no.: 20091035969.9), our flexible anode project won the national science and technology innovation fund for small and medium-sized enterprises.


               TYPE ELPA Data Sheet



 Flexible Anode Based On MMO/Ti Coating Technology (ELTA series)

sketch of flexible anode


This kind of flexible anode is based on MMO/Ti anode, cover with conductive polymer with carbon breeze bag.

The flexible anode embraces four parts as followed:

1. Continuous MMO/Ti wire

2. Continuous inner copper conductor

3. Continuous fabric jacket

4. coke breeze in place around the anode cable


Through power cable and MMO/Ti wire anode, use the method of a certain distance connection seal, to achieve the purpose of cable release and transmission.

Cable transmission current through MMO wire to release protection electric field, make up the composite cathode protection auxiliary anodes. The product has the following characteristics

1. Low resistance between MMO wire and cable.

2. High reliability of the connection

3. Sealing material of connection has excellent corrosion resistance and anti-aging.

4. Customizable Max current output

5. Testing of joints sealing.

  flexible anode

Advantages Analysis on Flexible Anode and Traditional Anode

Conventional Auxiliary Anode Ground Bed

Nearly 30 years of domestic experience in regional cathodic protection prove that anode ground bed ways and the location is critical for the success of regional cathodic protection. If ground bed methods or position of distribution are inappropriate, the trunk pipeline beyond the scope of protection and approaching metal structures will be intrusively. The network pipe concentrated area will fail to protect and the other area will over protect.   Conventional regional cathodic auxiliary anode ground bed mainly in the form of shallow, deep well anode etc.


Shallow-buried anode ground bed:shallow-buried anode ground bed is that one or several anodes are installed underground of 15 meters deep vertically or horizontally for cathode protection. It is for protecting the structure with single geometric shape, such as the single long-distance pipeline. Distributed shallow anode bed could be used for cathodic protection of the station area.


Deep-well anode ground bed is a type of ground bed that vertical mounting one or more anodes in a deep well hole underground ( depth usually greater than 15 meters ) , generally used in environment conditions of surface soil with high resistivity or narrow space, which cannot meet the shallow anode ground bed installation space and anode grounding resistance requirements. Deep-well anode ground bed has a high requirement on geological conditions, underground water, underground layer resistivity of soil and so on. 


Advantages of Flexible Anode

Flexible anode is soft long line shape auxiliary anode which covered by cable anode made of powdered carbon filler. It includes conductive polymer, metal oxide, and platinum niobium alloy. Conductive polymer is the first generation flexible anode, MMO flexible anode is the second generation of products. Two kinds of anode have similar shape as well as the purpose and methods of using, but the structure is essentially difference. Compared with the traditional deep well anode and distributed anode, flexible anode has the following advantages:


Potential and current are distributed more evenly, achieving more efficient protection.


Potential of traditional distributed anode pipeline - mileage chart


Potential of pipeline after flexible anode - mileage chart


Since flexible anode close to the protection object, hovering distribution evenly along with the pipelines and paved path. Output current is uniform, adequate protection current could be offered even if the anticorrosion layer of pipeline severely damaged or exposed, and over protection or protection deficiency could also be avoided. Small losing current and long life that is beneficial to reduce system output and offer energy efficiency for cathode protection.


But the distribution of the traditional graphite anode and present titanium tube anode string effect the distribution of protection because of that they can’t distribute along with the line pipe.  


Construction Conveniently

Flexible anode is placed alongside pipes to protect the pipeline, it can reduce the current loss, improve the efficiency of current protection. The prepackage coke breeze of flexible anode can save the steps of bury anode bed. For example, use cable laying equipment to bury it. The outer cover of flexible anode is canvas protection layer which is anti-friction and acid-proof alkali, there is no need to worry about the wear in the transportation, to security of the actual working life. It has more advantages than MMO coating anode. And flexible anode has no impact on the cathodic protection field when it needs to rebuild or expansion.


So take flexibility positive electrode with protection of complicate net work pipe, it can be avoided “interference, shield”problem. At the same time, the difficulty of design and execution can be reduced immensely, it is easy to guarantee mission success rate for project implementation. At present, that take flexibility positive electrode with protection of complicate net work pipe is a trend.   Since it have many unmatched character for flexibility positive electrode, it will become development and application direction for negative electrode protection of area of complicate net work pipe.