The unavailability of coal fired electrical generating capacity is often attributable to corrosion in steam generators. Electricity demand grows faster than new plants come online, forcing greater use of old plants. Identifying such problems requires proper inspection tools and techniques to take the guesswork out of whether boiler tubes should be repaired or replaced.
Stress assisted corrosion (SAC) is a major concern for kraft recovery boilers in the pulp and paper industry. A water leak can cause a smelt-water explosion in the boiler. A number of carbon steel tubes showed a deep decarburized layer on the inner surface (water-touched) and also an unusually large grain size at the inner tube surface.
Failure analysis methodology is applied to the principal mechanisms by which boiler tubes fail during service. sThe failure analysis procedure, or methodology for evaluation, is provided in a step by step approach. Among the case histories discussed are: fatigue, erosion, short-term overheating, and hydrogen damage.