Corrosion investigation of a steamturbine after power generator failure onboard a vessel: A case study

摘要

Steam turbines for power generation installed on vessels are designed to operate for over 30 years. However, there are some cases of untimely failures. In this paper, we are reporting a case of a deeply damaged turbogenerator, with several visible corrosion/erosion attacks, such as 'pit-shaped' defects, rust, and drains. While significantly widespread, they were almost only observed on the inlet steam flow side. Also, their extension and size were not such as to affect the integrity of the failed rotor, especially if we consider the size of its blades and discs. Some chemical elements not included in the alloy composition of the turbogenerator are detectable on the surface of the turbine components. Their presence could be due to passivation layers and/or material oxidation, in the case of oxygen, or, in the case of other elements detected in very low amounts and contained in the steam, to their deposition during standard turbine operations. However, turbogenerator storage conditions at the shipyard workshop before analysis might also be involved.