TRACK: Failure/Failure Analysis
Cast iron pipes are often laid underground and forgotten because, usually, nothing happens to them for decades. Over the past few years, several sections of cast and ductile iron pipe have been sent to my lab for failure analysis having all met the same fate: Graphitic corrosion caused by acidic soil (usually associated with salt for melting ice on roads and walkways) after ~40 years of service. This presentation offers a background into graphitic corrosion of cast and ductile iron pipes, including metallographic samples from field failures, and a discussion on the problems it has caused. A practical approach to identifying incipient graphitization is also presented as it was used to identify problem areas when installing a pipe restraint along with available methods to detect graphitic corrosion in buried pipes without excavation.