Failure Modes, Effects and Causes of Microbiologically Influenced Corrosion

Advanced Perspectives and Analysis

Reza Javaherdashti, Farzaneh Akvan

• Publisher: Elsevier
• Year: 2019
• Print ISBN:
  9780128184486
• eBook ISBN:
  9780128184493
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Failure Modes, Effects and Causes of Microbiologically Influenced Corrosion: Advanced Perspectives and Analysis presents academic research about microbial corrosion (MIC), integrating it into engineering applications that result in a more thorough understanding of MIC and how it is recognized and treated. In addition, new concepts that will be useful in understanding integrity and corrosion management practices are explored. This book will be useful for industry professionals, particularly maintenance and operation engineers, corrosion and material engineers, and R&D personnel working in the field of corrosion protection. - Focuses on the skills and knowledge necessary to understand how (Failure modes) and why (Effects and Causes) materials fail - Explains why corrosion control measures, such as the use of coatings, cathodic protection and inhibitors are useful - Discusses the practical side of MIC treatment in terms of fundamental concepts of time and cost of operation

Chapter 1

Introduction

The main topic of this book, as the title suggests, is to understand (or to understand what we understand!) what is meant by “failure modes, effects, causes, and analysis (FMEA)” as to be applied to microbial corrosion (MIC) so that we could talk about FMEA-MIC.

Our understanding is simply as below:

• 1. A failure has happened that we think it is/can be due to microbial corrosion (how do you know = failure mode analysis),
• 2. We also want to know the way this failure would affect the overall performance of the equipment and the safety of working with that equipment (effect analysis),
• 3. But, obviously, without knowing what caused the failure and how it caused it, we cannot find a way to control its effect or—even much better—prevent it (causes analysis).

Failure is the very last stage of a relatively slow, yet powerful process that can start with corrosion. In fact, due to thermo dynamical nature of corrosion, it is impossible to have “no corrosion.” At the best, one can say that corrosion is under control and not that there is no corrosion. However, if it is unattended, then failure will be inevitable. The main focus here is to “outsmart” failure. In other words, we must not let failure happen in the first place. This will logically require us to answer to the three items we mentioned earlier.

No matter what fancy names we use to address corrosion and corrosion prevention and control, it is always at the heart of the issue of corrosion that it is much more complicated than what we can see on the surface. A detrimental mistake, made particularly by inexperienced engineers, is that they try to estimate the corrosion mechanism by which failure has happened by just looking at “the crime scene,” that is the failure appearance. This is a wrong approach mainly because of the fact that it assumes that there is only one particular mechanism of corrosion that can be operative: this assumption may not always be necessarily true.

Failures of components and equipment can have various reasons; some of these failures could have resulted from human errors and some from technical issues. Perhaps among these technical issues, the place of corrosion is quite important: Of the budget to be spent on maintenance in a refinery, about 36% is directly due to the cost of corrosion and more than half of pipeline leaks is also because of corrosion. ¹

The role that human factors play in failures and particularly in corrosion-related failure cannot be ignored: A study ² that analyzed the factors involved in corrosion-related failures between 2001 and 2004 in the oil refining industry revealed that, on the average, 60%–80% of these failures had happened due to human factor. We, however, prefer to concentrate only on corrosion as the main concern for us in analyzing failures. In this respect, we do not prefer a particular industry over another: for us FMEA-MIC in oil and gas industry is as important as it may be in water treatment or food industry. The reason is that we are looking at corrosion per material not per industry.

There are various kinds of corrosion processes that, by the degree of damage they cause, can each be the focus of a book. During our professional life, we observed that it is as if each industry experiences one type of corrosion more than other types and it is like that a particular industry suffers from a main type of corrosion. In mining industry, for example, it is erosion–corrosion that can be taken as the “passion mark of corrosion,” in oil and gas industries it is “sour” and “sweet” corrosion and so on. Even so, in a given industry one can come across segments and parts of the industry that among other types of corrosion, experience one type more: in a thermal power plant working based on water-steam circuit, hot corrosion in boilers (water wall tubes), impingement on the first rack of high power turbine blades and electrochemical corrosion between the condenser and the boiler feed pump could be among the corrosion major players. In metallic fire-water rings and hydrants, it is microbial corrosion that can be the prevailing corrosion scenario. The list can go on and on.

A “corrosion per industry” approach mainly focuses on corrosion issues that are of interest to a certain industry (which is good) but neglects other industries that could, even by chance, have the same corrosion problems (which is bad). A “corrosion per material” approach, however, looks at the overall effect corrosion can have on a particular material per se without a particular interest in a given industry.

However, what is interesting here is that despite the confusing picture we may get at the first sight, there are certain general rules that can be applied to any plant, whether a refinery or a power plant or a dairy products plant: we call this as “general rule of corrosion risk” and will explain it later.

General Rule of Corrosion Risk

In any industrial plant, irrespective of the industry, there are three features:

• (1) The plant has its own production process or providing services
• (2) The dollar's value of the production or services is specific to the plant and the industry the plant belongs to
• (3) There is a safety issue to be observed for the industrial activities that are taking place in the plant. This safety issue will provide a safe production/service provision environment.

An example may serve to clarify the three features mentioned earlier: a power plant and an oil refinery and a port are examples of three plants that work in different industries: power generation, oil refining industries, and marine transportation services. Each plant has its own way of production and service provision that is unique to that particular industry pace and what each plant either produces or provides service for has its own market value. However, what is common among all the three is that safety must be provided. No one wants to work in a power plant or a refinery or on a port that is vulnerable to failure and possibly the risk of inducing damage to the environment and, even more importantly, to the personal who work there.

Corrosion is a safety issue. In the context of possibility of a failure being resulted from corrosion, it is corrosion that can be taken as the main culprit and therefore it is corrosion that has to be seriously considered, in terms of its control and possibly prevention (corrosion prevention and corrosion control are two very important instruments in understanding FMEA ion the way we treat it here in this book. We will define, and several times return to the definitions of corrosion prevention and corrosion control and the very important difference they have with each other).

Corrosion having such significance is to be studied in detail in terms of FMEA. We will try to exactly define what we mean by failure of an engineering asset not in terms of what engineering textbooks say but in terms of real life corrosion management. It is also important to clearly understand the causes that may be leading into these failures and how to address them properly by applying the best possible analysis techniques.

FMEA will become even more complicated when it comes to microbial corrosion; therefore, we have to prepare the stage properly for the main concepts that can be listed below as follows:

• (i) General rule of corrosion risk
• (ii) Corrosion prevention and corrosion control
• (iii) Zugzwang effect state
• (iv) Fit-for-service (FSS) and pseudo-FSS states
• (v) The link between the four elements mentioned earlier.

According to what we call as the “general rule of corrosion risk,” in any plant one can observe two categories of corrosion scenarios/risks: those related to the main process equipment and those related to the auxiliary equipment.

What we mean by auxiliary...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Author Biographies
• Foreword
• Chapter 1. Introduction
• Chapter 2. A Touch of Corrosion to Understand Microbial Corrosion
• Chapter 3. Microbiologically Influenced Corrosion (MIC)
• Chapter 4. FMEA-MIC
• Chapter 5. Innovation, Uncertainty, and FMEA-MIC and FCP-MIC
• Index