Corrosion Factors of Ductile Iron Pipe

Ductile iron pipes have been widely used, and our cities are connected by them, giving us thousands of conveniences. Ductile iron pipes have completed complex projects, and their cost performance is also very good.

Due to the continuous improvement and development of ductile iron pipes, the current ductile iron pipes are no longer affected by temperature and humidity. For some complex terrain conditions, they can also be successfully competent.

There are many reasons for the corrosion of ductile iron pipes, such as galvanic corrosion, microbial corrosion, heterogeneous electrolyte corrosion, stray current corrosion, etc. The following describes the control methods of ductile iron pipe corrosion from three aspects of preventing galvanic current, corrosive soil and increasing the wall thickness of ductile iron pipe:

1) Protection against galvanic currents

Insulated joints are used to break the metal electrical connection between two pipes, pipe components or structures, thus preventing the current from flowing between them. This method has been used in rubber gasket welding systems, and is considered to be a limited application of electrically continuous ductile iron pipes. Insulated joints are often used, but ductile iron pipes are isolated from other underground structures by cathodic protection or as part of the electrical grounding system. They can also be used at the junction of ductile iron pipe and copper service pipe to prevent galvanic current.

2) Corrosive soil

Backfill corrosive soil to reduce its corrosion tendency. It may only provide short-term protection for ductile iron pipes. In many cases, it is necessary to know the characteristics of surrounding soil when replacing less corrosive backfill materials.

3) Increase the wall thickness of ductile iron pipe

It is cost-effective to use sacrificial metal to allow metal loss (i.e. corrosion allowance) by increasing the wall thickness of ductile iron pipes, especially when pitting is the main failure mode of ductile iron pipes.