Crack advance has been studied in a X-70 pipeline steel, using the compliance technique. The electrolyte was very dilute brine bubbled with 10% carbon dioxide. Cracking rates were studied at a range of frequencies and R-values. The R-values simulated typical high-pressure gas service, but the frequency used was significantly higher. Similar testing was carried out in the presence of a 1% hydrogen sulfide using the Shell Canada sour gas test facility. The crack advance observed in dilute brine bubbled with 10% carbon dioxide could be explained using the rates of corrosion fatigue and a threshold......
Keywords: environmentally assisted cracking, external stress cracking, fatigue, corrosion fatigue, near-neutral pH stress corrosion cracking, hydrogen sulfide (H2S), carbon dioxide (CO2), pipeline steel.