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Petrochemical plants in the Arabian Gulf area use seawater to cool the reactors. After only a few years of service, many seawater structures have developed cracks and spalling of concrete from chloride-induced corrosion of the steel reinforcement. Cathodic protection (CP) was installed to mitigate this corrosion. The CP has been operating for 8 to 10 years. Its performance and assessment are described. The 100-mV decay criterion was met at most protected areas. In many areas, CP has shifted the free corrosion potentials toward less negative values by some 150 to 200 mV, indicating the restoration of steel passivity. A visual inspection of the protected areas has revealed no rust staining or concrete deterioration since the CP commissioning. [ABSTRACT FROM AUTHOR]

The thermowell inside the post-combustion chamber of an incineration plant failed as a result of severe high-temperature oxidation. An investigation showed that the failure was caused by deep intergranular oxidation and subsequent breakdown along the grain boundaries--in addition to gradual thinning of the component. The thermowell alloy was improper for this use because 1) there was insufficient Cr content for formation of a continuous adherent protective chromium oxide (Cr2O3) layer on the alloy surface under the operating condition and 2) the high operating temperature (950°C) approaches the upper temperature limit (1,000°C) for the alloy. The investigators recommended a silicon carbide (SIC) ceramic for replacement. [ABSTRACT FROM AUTHOR]

The article reports on a water-wall tube failure of a boiler that had been in service for 23 years. The boiler was experiencing several leaks and engineers examined the failed tubes to uncover the root cause of the tubes' bulging and leaks. A 1-mm thick deposit in the inner surface of the water-wall tubes was found to be the root cause for the tube failures.