The present paper compares corrosion rates from a recovery boiler tube during two planned
maintenance outages and respective re-starts. An acid-wash of the boiler tubes was performed
during the first outage, but not the second. A non-intrusive, online hydrogen effusion probe
was used to monitor hydrogen flux in real-time during both outages. Those two datasets were
then plotted side-by-side in order to compare the effect of the acid-wash on hydrogen flux, and
correspondingly, corrosion rate. This is believed to be the first successful attempt to
quantifiably compare boiler tube corrosion rates during and post-maintenance outage.
Key words: hydrogen flux, corrosion monitoring, online, recovery boilers, boiler tubes