Fatigue of stress corrosion cracks in X65 pipeline steels

A section of gas pipeline containing stress corrosion cracking (SCC) was removed from service and pressure cycled. SCC cracks were shown to have extended by fatigue. Fatigue crack interaction was found to be a large factor in crack growth characteristics. Crack interaction was found to be influenced by original SCC crack inclination and layout. Fatigue crack growth was found to be independent of original SCC crack profile or aspect ratio.