## 1 Introduction  
### General Background  
Nowadays, when building or reconditioning new facilities or infrastructures exposed to aggressive environments, designers tend to recommend the use of stainless steels (SS) for such purposes. It is true that stainless steels, mainly (AISI) 304, 304L, 316, and 316L, are well-known for their excellent corrosion resistance and good mechanical properties, so they have been widely used in a large number of aggressive environments and applications [1], most often with good results and performance. However, it is also true that SS are not free of corrosion issues, as it is mistakenly believed in practice. Thus, in many cases, it is not considered necessary to take any precautions or carry out a maintenance plan on the installation to fight against corrosion issues during the construction and/or exploitation phases; this fact has led to important economic losses due to in-service failures, or even during the construction phase, in a non-negligible number of cases. In this sense, different strategies have been proposed to avoid corrosion issues in this type of steel, including anodic protection (e.g., [2]), cathodic protection (e.g., [3, 4]), and the use of protective coatings, such as composite electrochemical coatings (e.g., [5, 6, 7]) and cold spray coatings (e.g., [8]), among others.  
Failure processes in metallic and non-metallic pipeline systems are extensively reported in the literature, covering a wide variety of failure mechanisms that include, for example, plastic collapse from local thin areas [9], brittle fracture [10], fatigue [11, 12], creep [13], and corrosion processes [14, 15]. When dealing with metallic pipelines used in water conduction systems, the main cause (not unique) of failures and leaks is corrosion, which may be additionally associated with non-adequate material selection, non-standardized construction processes, poor maintenance, etc. [16].  
Stainless steels are very commonly used for applications in the marine environment, which is one of the most corrosive natural environments in the world. Moreover, due to the influence of corrosive factors, such as temperature, dissolved oxygen, Cl\({}^{-}\), and pH, metals (including stainless steels) operating in the marine environment usually suffer from pitting corrosion, crevice corrosion, or stress corrosion processes, among others. This restricts the performance reliability of stainless steels in real applications [17; 18]. In addition, the microorganisms living in marine environments have a strong impact on the corrosion behavior of metallic materials [19]. The bacteria attaching and multiplying on material surfaces can significantly change the interface properties of the material by physical or/and chemical means, which is known as microbiologically influenced corrosion (MIC) [20].  
At the same time, MIC can take place in environments and working conditions where there are no other corrosion processes taking place, or it can appear in combination with other corrosion modes. More importantly, microorganisms can accelerate the kinetics of anodic/cathodic corrosion reactions in such a way that they can be viewed as \"catalytic\" entities. Microorganisms are also known to induce a localized attack, including dealloying, pitting, localized galvanic corrosion, and stress corrosion cracking [21].  
The economic costs associated with MIC in buried pipelines, marine, oil and gas, and other chemical plants are enormous. MIC-induced problems in buried pipelines/equipment have attracted a great deal of attention all around the world [21]. Some of the main concerns when facing MIC are that, on the one hand, it is a very fast type of corrosion (there are examples of pipes corroded in months-to-a-year timeframes) and, on the other hand, once it has started, it is very difficult to stop it and to guarantee the integrity of the affected piping system.