Received: 6 September 2022 Accepted: 24 November 2022
Abstract:
Under deposit corrosion (UDC) which caused internal corrosion has been contributed as one of the major reasons for corrosion failures in critical industries. Hence, UDC has garnered urgent attention from corrosion failure researchers. Based on the nature of the deposits and local chemistry, various mechanism for UDC is feasible and there is not any unique one. Moreover, its corrosion mechanism has become greatly complicated and increasing insidious effects of resultant corrosion damage because in most real-world cases UDC is integrated with microbiologically influenced corrosion (MIC). Although different sophisticated mitigation measures were developed to combat pernicious effects of UDC, still its alleviation is highly challenging and needs a full realization of the target system mechanism and involved deposits. In the present paper, the authors thoroughly spotlight the fundamentals and mechanisms of UDC. Furthermore, since the security and integrity of different facilities are adversely influenced by the presence of ammonium chloride as the major agent in localized corrosion, its mechanism is briefly discussed. Piping structures and overhead equipment are the most ubiquitous hotspots for ammonium chloride as a UDC. This pernicious type of corrosion gave rise to serious fouling which posed significant hazards to the operational durability of various processing units. In addition, different novel and industrial mitigation strategies are discussed for minimizing the corrosion failure induced by UDC. Finally, major limitations and future challenges are proposed to foster incessant advancements against industrial corrosion failures specifically motivated by UDC.