Corrosion behaviour of X100 pipeline steel under a salty droplet covered by simulated diluted bitumen

A NaCl-containing water droplet covered by simulated diluted bitumen was used to mimic the internal corrosion scenario that pipelines transporting diluted bitumen may encounter. The NaCl-containing droplet on the X100 pipeline steel shrank to a smaller droplet under the action of the simulated diluted bitumen. Hematite and lepidocrocite were identified in the corrosion products formed in the shrunken droplet. The dissolution of X100 pipeline steel primarily occurred at the edge of the central ring of the shrunken droplet. The corrosion attack morphology seen under these conditions is quite different from that of previous investigations for salty droplets in open air. The results point to a new mechanism of internal corrosion possibly appearing in diluted bitumen pipelines.