Corrosion of monel metal in photographic solutions

Abstract

In desalination plants the corrosion failure of components due to environment- related factors constitutes a major part of the reported cases. This paper presents a few interesting case studies of the failed components of SWCC desalination plants in the Kingdom of Saudi Arabia. It has been recognized that the biofouling of offshore structures of desalination plants combined with sulfide contamination are responsible for microbiologically-induced corrosion (MIC) of components. A case study investigating the failure of monel bolts in the seawater intake pump has revealed severe MIC attack by sulfide-reducing bacteria. Failure of materials from stress corrosion cracking (SCC) in service due to combined and synergistic interaction of mechanical stresses and corrosion reaction is not an uncommon phenomenon in desalination plants. The second case study concerns the investigation of a large-size, intermediate-bearing support block of a seawater intake pump. The results of the study confirmed that the failure is due to SCC resulting from the retained residual stresses during component manufacture. Another case study of the failure of the steam impingement plate of the desal chamber also indicated that the failure is due to SCC caused by the development of thermal stresses during plate reinforcement. The methodology adopted and the analysis of material/corrosion products carried out are detailed. The issues that must be addressed in order to control corrosion and/or failure are discussed.