Full‐scale testing of near‐neutral pH stress corrosion cracking growth behavior of a vintage X52 oil pipe

Abstract This study presents an experimental investigation conducted on a 40‐year‐old vintage X52 oil pipe segment to assess the growth behavior of near‐neutral pH stress corrosion cracking (SCC). Six cracks were introduced on the pipe specimen, each of which was associated with a unique combination of metallurgical and environmental condition. SCC growth was evident in two base metal cracks respectively exposed to C2 and NS4. Stress intensity factors at the two cracks were evaluated using extended finite element method. Near‐neutral pH environment effects were observed to have a more pronounced effect on the stress intensity factor threshold for growth than on the growth rate. Higher stress levels and aging likely contribute to the difference in growth rates of different cracks. Electrochemical analysis suggests the corrosion‐crack propagation interplay, with a faster corrosion in the NS4 solution than that in the C2 solution consistent with the observed slower crack growth in NS4. Highlights Full‐scale tests are carried out to investigate the growth of NNpH SCC cracks on vintage X52 pipe specimens. Stress intensity factors are evaluated using the extended finite element method. The stress intensity factor threshold for crack growth is found to be impacted by the NNpH environment. Electrochemical analysis reveals evidence of corrosion‐crack interplay.