Graphitic corrosion -- Don`t forget about buried cast iron pipes
Graphitic corrosion is a form of de-alloying or selective leaching that occurs in cast iron material. This corrosion mechanism is unique to gray cast irons and is caused by the graphitic matrix present. The graphite is cathodic to the iron matrix. Exposure to an electrolyte results in leaching of the iron matrix, leaving behind a porous mass of graphite flakes. Graphite corrosion often occurs in buried gray cast iron pipes, although exposure to an aqueous environment is all that is necessary for the de-alloying to occur. The process of de-alloying in cast iron typically is long-term, taking several years to occur. In fact, many cases of graphitic corrosion-caused failure in cast iron piping occur in piping that has been in service for 50 years or more. Mechanical testing to determine the tensile strength of cast iron can provide information regarding the remaining strength of the pipe.
- OSTI ID:
- 691429
- Journal Information:
- Materials Performance, Journal Name: Materials Performance Journal Issue: 8 Vol. 38; ISSN MTPFBI; ISSN 0094-1492
- Country of Publication:
- United States
- Language:
- English
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