EXTERNAL CORROSION OF PETROLEUM AND PETROCHEMICAL PIPELINES
Table of contents
Problem and its Background
Introduction
Background of the Topic
Aims and Objectives
Map of the Study
Rationale of the Study
Significance of the Study
Scope and Limitations
Review of Related Literature
Pipeline Corrosion
Uniform Corrosion
Pitting Corrosion
Crevice Corrosion
Galvanic Corrosion
Pipeline Management and Corrosion Monitoring
Control Systems
Coating and linings
Cathodic protection
Materials selection
Corrosion inhibitors
Remedial Actions
Synthesis
Methods and Procedures
Research Method
Research Tools
Administration of Research
Ethical Issues
Chapter 4
Presentation, Interpretation, and Analysis of Data
Perception of Pipeline Corrosion
Effectiveness of Control Systems
Coating and linings
Cathodic protection
Materials selection
Corrosion inhibitors
Prevention and Remedial Actions
Summary, Conclusion and Recommendations
Summary
Conclusion
Recommendations
Bibliography
Chapter 1
Problem and its Background
IntroductionThe most lucrative and possibly the richest industry in the world include companies that deal with petroleum and petrochemical products. As an essential commodity, these industries tend to be more of an indispensable component of the all aspects of business and trade. Studies have mentioned that the varying cost of these petroleum products and their petrochemical counterparts tend to augment the actual price in the market. Unfortunately, most if not all products are anchored in the actual price of these petroleum and petrochemical products. One of the major causes of wastage and cost-incurring occurrences in this industry is the presence of defective pipelines. In the process of transferring petroleum products and petrochemicals from point A to point B, it is inevitable for the transition to incur any systems loss. At the most, companies tend to give the burden of these lost resources to the consumers. In the instance where high costs are incurred, these may be attributable to the company’s weak pipeline reliability and consequent damages in its pipelines. The most prominent cause of such damaged pipelines is corrosion. This study shall take into consideration occurrence of corrosion on petrochemical and petroleum pipelines. In the research process, an in-depth discussion regarding the possible causes, methods of prevention and perceived remedies shall be provided. The arguments and observations made throughout the study shall be based on the past and existing literature on pipeline management and corrosion science.
Background of the TopicPipeline corrosion is normally caused by a lot of reasons, regardless on whether the pipe is underground or openly exposed. Corrosion could be triggered by the lack of protection or appropriate means of maintaining it. Without such protection from the elements, it is more likely that deterioration will be expeditious as corrosion will set in. Looking at this description, it appears that without the initiative to protect the pipelines, the effects would essentially be unforgiving. Corrosion shall basically take away the structural integrity of the pipeline. Without such strength in these pipelines, not only will these be an unsafe means of transporting petrochemicals and petroleum products, it will essentially be a drain for any company as it will induce wastage, hence lost revenue. Fortunately, advances in technology has made available for companies to provide some way of extending the lifetime of these pipelines. However these companies have to make sure that the application and maintenance of these pipelines and these technologies have to be appropriately done. This paper shall look into the methods on which pipelines could be protected from corrosion. The general intention of this study is to discuss four of the major corrosion control methods available for companies. These include coating and linings, cathodic protection, materials selection, and corrosion inhibitors. The following parts shall specify the aims and objectives of this paper.
Aims and Objectives
In order to establish the general goals of this paper, the researcher has to answer the following questions:
· How does the past and existing literature perceive corrosion of pipelines?
· What are the means of managing pipeline corrosion
· How effective are these control systems in defending pipelines from corrosion:
o coating and linings,
o cathodic protection,
o materials selection, and
o corrosion inhibitors.
· What is the best system for the prevention and remedial actions available for companies?
Map of the StudyThe study shall give a qualitative analysis of the works pertaining to petrochemical and petroleum pipeline corrosion. Specifically, an analysis of the approaches of preventing and management of corrosion such as coating and linings, cathodic protection, materials selection, and corrosion inhibitors shall be made. The dissertation is divided into several chapters. This division provides for a clear and cohesive line of arguments for the overall dissertation. The first chapter shall consider the background of the study. Specifically, the discussions shall cover elements that cover the problem of corrosion and how companies could benefit from preventing such occurrences. This chapter shall give the aims and objectives of this dissertation and the overall rationale of doing such a work. In the same manner, this chapter shall also discuss the scope and limitations of the arguments as well as the significance of the study on this field of knowledge, particularly pipeline management.
The second chapter will serve as this dissertation’s review of past and existing literature on the study of pipeline management, corrosion science, as well as pipeline reliability. The second chapter will basically be a synthesis of the research made by the author that seeks to realise the aims and objectives of the dissertation. More importantly, the discussions shall cover studies that looked upon the effectiveness of coating and linings, cathodic protection, materials selection, and corrosion inhibitors as means of extending the lifetime of a pipeline.
The third chapter of this paper shall provide for the discussion of the methods used in this paper. In its simplest sense, the third chapter shall be covering the models employed in the data acquisition and the modes on which the arguments are provided in this dissertation. Since this dissertation is more qualitative in nature, a discussion pertaining to the overall research process shall be highlighted. In addition to this, the third chapter shall also point out the ethical considerations that the researcher had to contend with in the completion of the paper.
The fourth part of this dissertation is the presentation, interpretation and analysis of the data. The chapter shall be discussing the issues pertaining to petroleum pipeline corrosion. Other topics shall cover the types of corrosion mentioned in the aims and objectives of this paper. In the same chapter, a set of discussions presenting the preventions and remedial actions that the industry have maintained shall be pointed out as discussed in the academic journals and articles. It is in this part of the paper that preventions and remedial actions shall be discussed.
The last chapter of this dissertation shall provide a summation of the arguments and observations done throughout the previous chapters in the paper. In the same manner, this chapter shall also provide a conclusion based on these findings, arguments and observations. It is in this part of the study that recommendations as well as the preventive methods available shall be given. All these are based on the observations, arguments and analysis made in the previous chapters of the dissertation.
Rationale of the StudyAs indicated in the earlier part of this chapter, corrosion takes away the structural integrity of the pipeline. This does not only take away the safety of the materials transported in the said conduit, it also translates to added costs, wastage, and eventual loss of future revenue. The methods pointed in the aims and objectives of this paper represent the technology available for the common organisation in its quest to ultimately do away with corrosion.
However, these organisations must realise that controlling corrosion is not a simple feat. It is a dynamic and continuing process that may in itself become a money drain for the company if it is not done appropriately. An amalgamation of technology, monitoring and maintenance is an essential element in ensuring the success of controlling corrosion. It is the intention of this paper to find out the most appropriate approach in achieving this level of success in controlling corrosion and thus extending the useful lives of pipelines.
Significance of the StudyThe existing literature on pipeline management and corrosion science is rather scant. This paper intends to add up to that list and provide a detailed description of the four available approaches in pipeline management. This study shall be giving the existing literature a much needed comparison of these approaches. Students of engineering shall benefit from the findings of this paper as a summary of the levels of effectiveness shall be given in the end of this paper. In the same manner, the petrochemical and petroleum companies will also benefit from this paper. The discussions on pipeline management shall provide conclusive recommendations and remedial actions that could increase the useful life of their pipelines and in the process save them a whole lot of resources. More importantly, the study shall also benefit the consumers and society in general as the savings made by these companies entail lesser costs on which the end users tend to shoulder. All in all, this dissertation will benefit a whole range of areas from the business side of the fence, to the academic perspective, and the end-users of the product.
Scope and LimitationsThe arguments and observations that shall be provided in the course of this paper are solely based on the rationale provided in this chapter as well as the main objectives and aims of this study. Given that the discussions are based on qualitative research, this means that majority of the sources and authorities used in this study are from previous data and studies on this field. This also requires the researcher to take a higher stand on the ethical processes made in the course of this research. The importance of proper citation must be pointed out as well as the elimination of any researcher bias in the process. Though it is not easy to dispense with, the researcher should be able to treat this data objectively such that issues on manipulations and lack of neutrality will be tackled with no trouble.
Chapter 2
Review of Related Literature
The previous chapter provided the background on the importance of studying pipeline management and the inherent potentials that it offers organisations. In this part of the study, the definition of the major concepts in the study shall be provided based on the provisions from existing literature.
Pipeline CorrosionCorrosion, in it simplest sense, is the wear and tear in an object induced either by natural or chemical elements that it is subjected. In the oil and gas production industry, it is imperative to manage corrosion in its pipelines. In the report provided by the (2002), it is said that management of corrosion is geared towards several benefits. One given is for compliance of the company with the Safety, Health and Environmental policies of the government. Like any other state with a lush industry for fuel, the UK implements a series of legal regimes that covers not only the protection of the oil and gas industry but also to ensure respective integrity of the facilities used in the working environment. In the same manner, the employment of corrosion management tends to benefit the individual companies as well. The report of the HSE also pointed out that corrosion management tends to reduce leaks, increase plant availability, reduction in unplanned maintenance, and reduce deferment costs. Seeing these elements, these all reflects the business effects and operational implications of implementing a corrosion management initiative in the organisation.
In the said discussion, the purpose of safety catches the attention of the researcher. This essentially seen in the literature as pipeline accidents has taken a lot of lives in the past years. For instance, there has been an increase of 4% in the pipeline accidents in 1989 and 1998 in the United States killing at least more or less 226 individuals. ( 2002, 22) In Russia, the non-compliance of pipeline contractors with the world standards made it “difficult to detect damage and so prevent leakage of gas, oil and oil products.” ( 2001,) This means that there were several unreported cases of accidents which approximately amount to over a thousand annually. In the same lines, it has been also noted that there were “insignificant leaks” that occurred because of the lack of supervision and failure to meet international standards. (2001,) mentioned that there were 40,000 leaks that occurred per year in the said country.
Uniform CorrosionUniform corrosion is basically a caustic attack arranged squarely in the whole exterior or the surface area. In the same manner, this corrosive attack could also form part of a greater portion of the overall area of the material. In the discussion on studies pertaining to this type of corrosion, they described the damage done by this corrosion attack as a process of general thinning. The thinning continues if not checked until the material fails its purpose. The great thing about this type of corrosion attack is that it is readily measured and calculated. Looking at this claim, one could surmise that disastrous failures occurring from this type of corrosion attack would be rather uncommon and would basically reflect utterly poor pipeline management.
Studies have also mentioned that the corrosion attack could easily be controlled. Complex processes from cathodic protection to mere painting of the metallic surface extend the useful life of pipelines. Other studies similarly mentioned the aesthetic element of uniform corrosion as it adds appeal as the discolouration and shifts in hue tends to manifest in the surface of the material. This would only be beneficial if the said material is erected for the sole purpose of adding visually appealing images. In the case of pipelines for petroleum and petrochemical transport, function triumphs over aesthetics at any given day.
Figure 1. Uniform Corrosion
Uniform corrosion takes place when the coating system that shields the metal structures collapse. This is often manifested by the reduction of shine in polished metals and discolouration because of oxidation. The common denominator in this respect is that these corrosion attacks are manifested in the surface of the material. For instance, pipelines that are initially stainless and those that include corrosion resistant alloys could become discoloured by virtue of the elements in its environment. The neglect of this corrosion attack will initially make the surface of the metal material rough but totally disregarding the entire problem would lead to material damages of higher proportions.
Pitting CorrosionSome types of corrosion attacks are more localised as compared to the uniform types of corrosion that spread all over the material. In localised corrosion attacks, specific parts of the material are damaged severely compared to the other parts. These damages are manifested by cavities or holes, thus the term pitting corrosion. In these types of corrosion attacks, detecting the damage in the material is more complex as compared to uniform corrosion. Basically, the pits implicated by these corrosion attacks are normally concealed under a layer of corroded area.
Figure 2. Pitting Corrosion
This means that the holes and other cavities are not readily or immediately detected, not until the severe damage has already been done.
The pits in this type of corrosion could take on a couple of form, trough pits or sideway pits. Though these damages appear to be superficially negligible, these cavities will fundamentally affect the overall engineering system of a particular machine. This is especially true in pipelines as pitting corrosion tends to be among the initial steps that lead to leaks and consequent wastage.
Studies on these types of corrosion attacks claim that pitting is triggered by a confined chemical or mechanical damage to the covering oxide film of the material. This is also manifested in factors affecting water chemistry which sets off the failure in the material that is supposed to deflect the effects of acidity and other concentrations from the environment. Pitting could also be prompted by the mismanagement of the material itself. For instance, pipelines are susceptible to pitting if the protective coatings placed in these materials are applied in poor form or the coating itself is of questionable quality. In the same manner, the actual material used in the piping system might also be the reason for pitting. The existence of some inconsistencies in the surface and even the inclusion of non-metals in these pipes could render the pipes highly susceptible to pitting corrosion.
Crevice CorrosionAnother type of localised corrosion, and equally damaging, is crevice corrosion. Studies have pointed out that such types of corrosion attacks tend to manifest itself on the micro-environmental level. This means that crevice corrosion takes place on miniature areas such as washers and joints. Basically, these take places in areas where crevices or gaps are present. Corrosion in these areas on the other hand is triggered a considerable amount of causes. One possibility is the significant reduction of corrosion inhibitors in the gaps. This then sets off deterioration in that area. This could also take place when the oxygen content in the said crevice is significantly diminished. There is also the possibility that the acid conditions became unbalanced for some reason. In this case, certain abnormalities have taken form thus setting off an imbalance in the actual structure of the material hence making it susceptible to corrosion attacks. Aside from a shift in the chemical balance of the material and the significant depletion in these materials, corrosion could also be triggered by a significant accumulation of some destructive elements in these gaps. These aggressive and consequently destructive elements could be chloride, especially true in pipelines submerged in seawater.
Normally, restricted dispersal of oxygen in these gaps plainly places the reason why corrosion builds up. The existence of the differential aeration cells the lies linking both the microenvironment and the bulk environment completes the formula for disaster. The more commonly seen form of this type of corrosion attack is called oxygen differential cell corrosion. This takes place in the instance where moisture has a lesser content of oxygen at times when it is located at the gap compared to when it is in the surface. In this situation, the moisture in the crevice builds an anode in the metal surface. In the same manner, the part of the metal surface that is connected to the layer of moisture and is open to the elements builds a cathode. It is in category that crevice corrosion is made. The figure below summarises the stages on which the crevice corrosion takes place.
Figure 2. Crevice Corrosion
In the first stage, it shows that the oxygen content of the moisture is equal to the soluble oxygen throughout the material. This is basically the case before corrosion sets in the metal. In the second stage, the oxygen acquired by the normal uniform corrosion is reduced at a much faster rate in the gaps. It is at this point that reactions between the gaps and the open surface is formed.
The third stage of the process presents the existence of accelerating elements that induces the development of corrosion in the crevices of the material. In these areas, the metal ions that the anodic corrosion reaction generates automatically break a bond in the existing molecules by adding in water in the formula. This gives off acid that adds up to the corrosion of the material. The negative algorithm of the hydrogen ion concentrates in the material then sets off at a very acidic value which then accelerates corrosion. The other product that ensues in the corrosion of the material is also observed to seal the crevice hence maintaining the constant deterioration of the metal. Other studies point to the individual charges of the ions in the crevices which contribute to the overall corrosive acceleration of the metal. Specifically, the positive charges of the metal crevices increases until it attracts elements like chloride that is basically aggressive elements that induces corrosion. It is thus apparent that in the case of crevice corrosion, once the chemical elements trigger deterioration, the progression would be continuous and aggressive unless there are certain actions taken to prevent the total destruction of the metal material.
Galvanic CorrosionAs mentioned in the earlier parts of this chapter, corrosion could be triggered by inherently different elements present in the material itself. There are instances where the existence of dissimilar metals would trigger an adverse reaction which is compounded by a corrosive electrolyte. This then sets off a form of galvanic corrosion. In the instance when the two elements combine, the metals present acquire the role of the anode and corrode as well as a cathode and corrode. One metal shall become faster than the other.
Figure 3. Galvanic Corrosion
The said process is manifested in Figure 3 above. In order for the actual corrosion induced by these galvanic elements to take place, there are certain requirements that need be satisfied. First, there should be electrochemically different metals in place. Second, these two metals should be in contact and third these should be exposed to an electrolyte. For instance in pipelines, the difference between a screw’s electrochemical compositions from the composition of the actual pipe would inevitably trigger a galvanic corrosion.
In the onset, this type of corrosion could easily be prevented by measuring the corrosion potential of the material used. The best way to measure the reliability of the material, the galvanic series should be taken into consideration. Basically, this series is a list of metals that measures its nobility when it is in contact with sea water. Normally, a minute anode to cathode area ratio is high is considered adverse. When this ratio is present, it will basically indicate that a small area of the material would be susceptible to the concentration of the galvanic current. It is in this same situation that the anode is dissolve at a much faster rate. Hence, with a rather rapid progression in the process of corrosion, then the damage would progress in a rate which could not be remedied immediately. It is apparent then that the best way to ensure that the full brunt of galvanic corrosion is not encountered is by preventing it in the first place.
Pipeline Management and Corrosion MonitoringThe operational aspects of pipelines cover a bulk on maintenance and extending its operational life. The (2002) coined the term corrosion management in its report. This report mentioned that corrosion management covers activities that deal with integrity risks which include the corrosion, cracking, and embrittlement of pipelines in its operational life. To summarise the report, it basically pointed out that extending the operational life of pipelines entails proper corrosion management systems. This could be acquired by initially considering the individual pipe’s in terms of design, actual stage in the life cycle, the process conditions, and operational history.
Corrosion management is defined in the concept of corrosion management as a mere part of the overall system of management which specifically engages in the development, implementation, review and maintenance of the corrosion policy of a particular company with regards to their pipelines.
The said report further highlighted the need for an effective policy to ensure that the risks mentioned in the earlier parts of this chapter shall not take place. The identification of risks which are linked to the occurrence of corrosion as well as the creation of a reliable control measure is said to help any petroleum or petrochemical company in establishing an effective corrosion management initiative.
The report also indicated the importance of having an effective plan in controlling, monitoring, and reviewing the preventive and protective measures of the pipelines. In doing so, the welfare of the employees is also taken into consideration. This is imperative especially in pipelines that are offshore. Hence, safety management is crucial in its operations. This framework is summarised in the figure below.
Figure 4. Corrosion Management Process
Seeing the framework above, it shows that the process have to include an amalgamation of both managerial and technical levels in the company, the complexity of the operations hence depends not only on the magnitude of the operations but also with the complementarities of both the management and the technical aspects of the operations.
Control SystemsControl systems are elements that help companies in dealing with the problem of pipeline corrosion. For the purposes of this study, four of the most common approaches in dealing with corrosion shall be taken into consideration. Discussions on coating and linings, catholic protection, materials selection, and corrosion inhibitors shall be taken into consideration.
Coating and liningsThese are principal tools available for companies to protect their pipelines from corrosion. These are normally interposed with the system of cathodic protection. The combination of these two systems are said to provide the highest possible protection for pipelines. Protective coating is divided into two major categories, organic and metallic coatings. Without these protective coatings, the possibility of metallic substrates which often are the structural components of major pipelines will deteriorate at a faster rate. In the case of organic coatings, there are categorised into convertible and non-convertible coatings. Both types of coatings are essentially composed of a curing mechanism. For the non-convertible type of organic coating, the curing mechanism is particularly impressed by the evaporation of certain solvents which does not induce change in the prevailing conditions of the resin. In the same manner, there is the possibility for these elements to dissolve in the solvent which are used in the initial instance where the resin is dissolved. With regards to the convertible coatings, the curing mechanism is basically composed of a process of polymerisation that gives resins chemical changes. These changes nonetheless, as compared to the non-convertible organic coatings, are incontrovertible once it is changed in its chemical structure.
Articles on these types of organic coatings include chlorinated rubbers, acrylics, and oxygen-induced polymerised coatings. The first two examples mentioned are non-convertible types of organic coatings. Chlorinated rubbers are formed when a polyolefin is mixed with chlorine. The curing in these types of coatings goes through the process of modification so as to acquire a high level of solid structure and to eliminate the brittle nature of its original state. On the other hand, acrylics are elements that are composed of polymers dissolved originating from an acrylic acid and acrylonitrile. Pipelines are usually interposed with acrylics which are water-based. The reason primarily is to afford the companies ease of application as well as to bestow the material a heightened weathering property.
In the realm of convertible coatings, alkyds and drying oils are the most commonly used elements in the business. The former are composed of primers and topcoats. These are essentially oil-based. Basically when applied in the pipelines, a film is placed in its surface. This is formed with reaction of the oxygen and catalysts. Upon reaction, the solvent present in the materials evaporates. The more readily accessible alkyds are seen in spray paints. On the part of drying oils, the shielding film placed in pipes is composed of oils and lacquers that infiltrate the material.
On the other hand, metallic coatings are comprehensively used in the market as they provide greater protection as compared to their organic counterpart. The more common metallic coating employed is said t be galvanizing. For the most part, galvanising is composed of metallic zinc and carbon steel. These are applied as a film on pipelines so as to control the process of corrosion in these types of materials. More specifically, there are two types of metallic galvanising: hot dip galvanising and zinc coating. In the latter type, the zinc is alloyed to the actual metal in the process of galvanising. On the other hand, the mode of hot-dip galvanising does not involve alloying and as the name implies, the process is completed by dipping the material in molten zinc. Nonetheless, the mechanisms used on both of their protective purposes are fundamentally similar. Studies have indicated that the protection provided by the galvanising process depends entirely on the thickness of their respective layers.
Cathodic protectionThe process of cathode protection is among the more common and one of the considerably complex approaches in corrosion management. The principle behind the process involves the anode, the cathode and a line of current that prevents corrosion from taking place. Specifically, it involves the connection of the external anode to the metal pipe with an electrical current to change the configuration of the metal into more of a cathode. In doing so, the prevention of corrosion is considerably increased. Normally the type of electricity used in the prevention of corrosion management comes from DC power sources. The use of the electrical element of the process rests on the electrochemical assumption that the electrical potential involving the metal as well as the electrolyte solution is to establish a more negative charge once it comes in contact with each other.
Companies prefer the use of cathodic protection approach as their major anti-corrosion treatment. Normally, this is applied in structure, preferably coated to give protection on the pipelines. This is especially true in areas where there is a possibility that the coating may be spoiled in some manner. In the same manner, companies from the petroleum and petrochemical industry tend to prefer this mode because it could be readily applied to existing structures. In doing so, these structures’ lives are extended so as they could operate longer.
Indicating the specific utilisation of cathodic protection as a means of protecting the pipeline would veer away from the provision of a corrosion allowance to sections of the material that are inherently thin which companies find expensive to construct. Studies have indicated that cathodic protection tends to become the much preferred means of protection from corrosion in instances where the companies could not afford to have the slightest of leaks in their pipelines. In this sense, both protection of the environment as well as the avoidance of wastage and lost revenue will be ensured. Normally, cathodic protection is used in steel materials that are immersed in water or buried underground. Thus, most pipelines tend to employ this type of corrosion control mechanism.
Materials selectionIn the process of materials selection, engineers tend to acquire certain materials which possess an inventory of qualities that are inevitably advantageous and essential to the project. The problem in this regard is that the needed requirements and selection criteria are rarely seen in a single material. This is especially true in the case of pipelines where the conditions wherein they operate are rather aggressive in terms of corrosion building. This is because these materials are normally submerged in seawater or underground.
Studies have indicated that a large number of companies use iron and nickel-based materials in their pipelines. Specifically, these companies tend to use these types of materials in their pressure vessels and other fittings used in the operations of the pipelines. In the same manner, ferretic alloys are also employed to protect pipelines in areas where the temperature us approximately 650 degrees Celsius. Normally, these ferretic alloys are composed of chromium and molybdenum. However, compared to the other materials used in the industry, the use of ferretic alloys are considerably more expensive. This increase in cost nevertheless is well founded as the material imposes higher strength, oxidation, and offers considerable resistance on the oxidation and suffixation of the material. Moreover, these elements also add up to the capability of the pipeline to take away the vulnerability of the material to the effects of hydrogen.
Since there is a dearth in the source of a perfect fit in relation to the materials needed for corrosion control, there are companies who opt for material fabrication and specific design to meet the needs of the public. In doing so, the materials used by the company are able to measure up with the expected stresses as well as the initial criteria wherein engineers have formulated prior to the operation of the project.
Corrosion inhibitorsLike any other means of corrosion management technique, corrosion inhibitors are normally placed externally to protect pipelines from corrosion. Corrosion inhibitors are chemicals which have a certain reactions when in contact with a surface of metallic material. The process basically consists of an inhibitor adsorbing itself to the pipeline. This means that it accumulates in the exterior part of the pipeline. The process of applying an inhibitor takes on several effects on the progression of corrosion. For instance, the application of a corrosion inhibitor would increase either the anodic or cathodic behaviour of the metal. More specifically, the application of an inhibitor would provide more space between the cathodes and the anodes in the metal hence reducing the possibility of corrosion. Similarly, corrosion inhibitors are able to diffuse ions to the metallic surface. This effect basically depends on the type of corrosion inhibitor used. There are products in the market that specifically does this attribute of reducing the movement of the ions which then reduces the possibility of corrosion. Aside from these effects, the electrical resistance of the metallic surface is increased by corrosion inhibitors. In this regard, the company is able to manage the flow of electrical charges in pipes so as to maintain a charge that would essentially repel corrosive elements. On the whole, corrosion inhibitors are slightly similar to coatings and linings. However, the major distinction between the two types of corrosion control tools is that corrosion inhibitors often affect the electrical charges and ions of the materials. In the same lines, the protection provided by the corrosion inhibitors is largely on the external part of pipelines.
Remedial ActionsThe existing literature has provided the certain remedial measures that would work on the implications of corrosion. For this paper, the researcher uncovered several important elements in dealing with corrosion. Studies could not stress enough the importance of data acquisition in the process. For instance, there are studies that look into the gasses on which the pipelines are subjected. This study pointed out that each type of gas has an effect on the corrosion development of the pipeline. In the same manner, the level of corrosiveness of the water, for those pipelines which are submerged, is also deemed important. Elements such as the linear polarisation and electrochemical impedance spectroscopy are used to measure such corrosive nature of these elements. On the whole, the operational parameters of the company should be taken into consideration to establish a type of corrosion control initiative that would fit perfectly with the needs of the company.
Another way of dealing with the protection of the external part of the pipeline is by chemical treatment. Studies have noted that this could only be carried out effectively once the data has been established. In the process of chemical treatment, the inhibitor is selected, particularly one that will fit the needs of the pipeline. Along with the right dosage and other inhibitors, the use of chemicals is often associated with the application of coatings, linings, and corrosion inhibitors.
And finally, to actually prevent corrosion from taking place in its pipelines, companies must take on measures in monitoring their pipelines. This is in line with the first element, particularly data acquisition. Companies have to acquire the relevant data to become aware of what is needed to be done in the process. However, these data must be up-to-date and acquired in a continuous manner. This will guarantee that the company shall be able to exercise some form of flexibility in their operations, particularly with the management of their pipelines.
Synthesis
Chapter 3
Methods and Procedures
This chapter shall be giving a description on how the data used in this paper is acquired in the research process. Particularly, the discussions shall include the research method and the manner on which these acquired data are to be analysed and interpreted. In the same time, the ethical issues that the researcher encountered shall be covered in the latter part of this chapter.
Research MethodGiven the limitations of the study with reference to the time and other financial elements in the process, this dissertation shall be using the descriptive form of research. There has been a considerable amount of studies that uses this form of research and quite the same number in terms of variety is present. For this study, the definition provided by (1996, 18) shall be employed. He noted that the descriptive research deals with “questions of what things are like, and not why they are that way.” More importantly, further pointed out that the use of the descriptive research in a particular study highlights the existence of a problem which could then trigger attempts towards action. This would be very useful in this area of study as the useful lifetime of pipeline tends to vary depending on the approach used for corrosion management. This dissertation shall present the strengths and weaknesses of the approaches provided in the earlier chapters.
In the same manner, this paper shall also use qualitative research in the process. This complements the use of the descriptive method in the earlier chapters as qualitative research shall be unravelling “why” such circumstances exists. For the most part, this use of qualitative research points to the analysis of the unstructured data acquired from the existing literature such as academic journals and articles on corrosion management and other subjects on pipeline control. The researcher realises that using such a method entails a cluttered process of analysing which would even be time consuming. However, it is one of the major aims and objectives of this study to uncover and explore the main issues of the topic and in the process understand how to manage it and deal with it in future occasions.
Research ToolsFor the purposes of this dissertation, the qualitative method to be used is document studies. This means that the research tools to be used are those existing records regarding the methods provided for in the earlier chapters in this paper. Hence, the past literatures shall be the main authorities used in this paper.
In using this type of method, the researcher is able to acquire existing sources which may be readily available and inexpensive. In the same manner, these items shall be based on the setting as well as in the language on which they take place. Hence, the studies used in this paper shall include primarily those in the English language. Moreover, the use of this mode of qualitative research allows the researcher to present the value of the study with reference to the varying views of the existing literature. It allows for an unobtrusive observation of the developments of the approaches of corrosion management throughout a particular period. All these stated above appears to be the positive effects of document studies. One must realise that the study also runs the risk of having an incomplete findings. It would also encounter challenges of authenticity and inaccuracy. Nonetheless, the researcher will be taking the necessary precautions and ethical considerations to avert any of these allegations.
Administration of ResearchThe bulk of the research in this paper shall be acquired from the World Wide Web. This is to ensure the breadth of the scope of the research. In the same manner, some of the data shall also be acquired from the libraries of the university. In the case of online research, the researcher shall use search engines like Google and Yahoo! to locate online libraries that cater to the subject proper. Such online libraries shall be the source of all the books, articles, and studies that will form part of the document study required in this paper’s qualitative analysis. The acquired documents shall then be manually administered and sorted by subject and by category depending on the needs of the aims and objectives provided for in the earlier chapters.
Ethical IssuesThe discussions in the earlier parts of this paper presented the risks that the researcher may encounter unless utmost care and caution is taken. This could be done by being aware and vigilantly following what is considered as ethical in the process of research. Being a study that relies heavily on secondary material and existing work, the researcher shall take into consideration the proper citation and referencing of these works. In the same manner, the researcher shall also make sure that the works used in this paper are heeded entirely so as not to provide a construction reverse of what its authors actually intend to present. Moreover, the interpretations provided in the research process shall be made with such liberality so as to favour both the researchers and the readers of this study.
Chapter 4
Presentation, Interpretation, and Analysis of Data
The previous parts of the study have presented an account of corrosion in general. In this part of the paper, a closer look on corrosion, particularly in the case of the external parts of the pipelines shall be taken into consideration. This chapter shall be divided into several major areas of discussions. First, a description on the general perception of pipeline corrosion will be given. In this part of the discussion, a generally accepted definition of pipeline corrosion shall be provided based on the existing data acquired by the researcher.
The second part of the chapter shall cover what has been deemed as the proper mode of the pipeline management. This will discuss the findings of the studies that pertains to pipeline management and prevention of corrosion in the external parts of the pipelines. Contrary t the first fart of this chapter, this part shall be concise and rather succinct. The third part shall contain a more detailed look on the control systems discussed in the second chapter of this paper. Once again, a discussion of the systems of coatings and linings, cathodic protection, materials selection and corrosion inhibitors shall be taken into consideration. In the end of the chapter, a discussion on the available prevention and remedial actions on companies based on the discussions in this chapter as well as those pointed out in the previous ones.
Perception of Pipeline Corrosion
As indicated in the previous chapters, corrosion is said to be a naturally occurring phenomenon. It is similar to any natural calamity that tends to induce some form of deterioration on anything that is made of natural elements. Corrosion, in its simplest sense is characterized as then as a natural reaction of metals with its direct environment. Like natural calamities, the repercussions of corrosion to these elements, more specifically on pipelines are expectedly costly and not to mention pose some high risk on the environment and the people that are directly involved in its maintenance.
Seeing this reality, it is inevitable for companies that use pipelines to transport their merchandise from Point A to Point B to make sure that such occurrence is managed. As seen in the discussions in the earlier chapters, the existing literature impressed the importance of corrosion management in the operations of the company. In the same manner, it has manifested the importance of the corrosion control systems that has been developed throughout the years. For countries and economies that depend on this type of industry, particularly petrochemical and petroleum industry, the protection of their pipelines is one of the more prioritised endeavours in their operations. Billions of dollars shall be saved on costs and other remedial actions alone once pipeline corrosion is addressed in an opportune manner. However, this does not end there. It this study contends that it is a process and an amalgamation of all the existing processes on corrosion management. The actions done before the actual operations are only as important as the actual management of the control systems imposed in these pipelines.
Effectiveness of Control Systems
This part of the chapter shall be discussing the effects of the control systems on the pipelines. More particularly, a discussion on the application of these control systems shall be provided and the consequent elements that may induce the failure of such protection of the external part of the pipelines.
Coating and liningsIn the study of (2007), they pointed out the standards used in the External Corrosion Direct Assessment (ECDA) scheme which are employed by majority of companies that operate pipelines. The study observed several reactions of pipe coatings and linings on the corrosive nature of the environment. For instance, pipe coatings made of polyolefin are said to be vulnerable to ultraviolet degradation and cracking failure. This is especially true when the pipelines are buried underground. The same study also pointed out the permeability of polyethylene. The study noted that oxygen and water vapour provide some form of permeability on the pipelines once corrosion sets in the material. Normally, the adhesion of the coatings will severely diminish in the process.
In underground pipelines, the study uncovered several externally driven failures of pipeline coatings. For instance, the backfilling of underground pipes tend to damage the coatings in the materials. Crown cracking are said to be the more common effects of the backfilling of the pipeline. The same study also pointed out that pipelines in clay soil tend to wrinkle the coatings when subjected to the expansion on wetting and contraction when drying of the clay soils. On the other hand, soil creep also induces failure on the pipeline coatings of the pipeline system. This is especially true in areas where unstable slopes are still in existence.
The study also manifested important findings on the effect of temperature and microbial degradation on the coating of the pipelines. The study mentioned that when coatings are subjected high temperature, the coating system is considerably changed. This means that the configuration of the coatings is altered to the point that even the purpose of protecting the pipelines is significantly lessened. This similarly true when soil microbes invade the coatings of the pipelines, the study said that the permeability of the coating is increased as this takes place. In this regard, this shows that when the pipelines are buried underground, the coatings and linings serve as the last line of defence when these types of elements already set in the pipes. Moreover, once there is failure on the side of the pipelines, this could indicate that the other forms of corrosion control systems used in conjunction with the coatings and linings have already failed.
Cathodic protectionNormally, cathodic protection is made as a mechanism to protect pipelines which are underground. The assault of corrosion on the surfaces of the metal pipes as it comes in contact with the soil consists of a couple of basic mechanisms. These two mechanisms include direct soil corrosion and stray current attack. These two mechanisms are naturally electrolytic. In the case of direct soil corrosion, the deterioration takes place because of the existence of certain corrosion cells in the exterior of these pipelines. On the other hand, the stray current element points to the existence of externally controlled currents that make the pipe exteriors that are in contact with the earth triggers the deterioration process.
In these instances, underground pipelines are usually taken to the application of cathodic protection. Studies have mentioned the need to consider soil sensitivity in the process of cathodic protection. This is important as the soil surrounding the pipeline tends to be a part of the cathodic protection current path. In addition, the pattern of the ground bed should similarly be considered as an important element in the process.
Other studies point towards the importance of the pipe-to-soil potential. This basically is measure of the potential between the pipe and a copper electrode. Along with this measure is the presence of the line current. This is essentially the process on which a current is moving longitudinally to determine the ability of the coatings used to protect the pipes from leakage and maintain a level of conductibility in the process of cathodic protection.
Other studies point to the importance of longitudinal resistance and current density. The first one points to the variation in the resistance of different types of steels. In the same manner, this part of the cathodic protection process points the determination as to whether the tolerance of the pipelines differ from one part to another depending on the weight of the said parts. Current density on the other hand, is rarely measurable for certain types of soil condition. However, it is crucial in providing the company a means on which to determine the design purposes for their respective pipelines in line with their cathodic protection initiatives. Along these lines, the information provided for by cathodic protection is a great marker of the quality of coating used in the process.
Materials selectionThe discussions on the second chapter of this dissertation pointed out the limited possibility for companies to find ways to acquire a fit based on their pipeline needs. This prompts the process of material fabrication on the part of the organisations. However, it must be pointed out that there are certain materials which are considerably excellent when it comes to their mechanical capacities and their ability to oppose the possibility of deterioration by means of corrosion. The problem with these elements is that they are rarely used by companies because of the fact that their structures are not susceptible to fabrication. This means that the possibility of these elements to fit what companies require as a part of a prearranged standard of quality with regards to their pipelines will not be met or, at the most, be minimally addressed. Hence, buying such materials would only induce waste on the part of the company. In the same manner, some studies have also pointed out that selecting materials should also consider the maintainability of the pipelines. Studies have pointed out certain materials that similarly have the same excellent properties and can be subjected to fabrication. However their structure is also considerably susceptible to immediate maturation. In this regard, these studies show that the major elements to be considered in materials selection is the capacity of the material to be maintained for a long time and its actual capability to subject itself to fabrication without compromising its original structural integrity.
There are also studies that point to the potential of alloys to have greater fabrication ability as compared to other metals. Articles and studies have pointed out that these types of metals are more capable of enduring higher applications of certain metals like carbon or tungsten. The end result would be a much higher performance enhancement of the material with reference to its mechanical properties and even corrosion resistance. However, there are mixed reactions in the advent of technologies as those that offer the conventional materials are threatened by more novel types of applications. For instance, the modes provided above like corrosion inhibitors are among the more forthcoming technologies especially in the inclusion of other tools like nanotechnologies.
Corrosion inhibitorsAs stated in the earlier chapters of this paper, corrosion inhibitors are readily accessed in the market. This entails numerous products and consequently numerous alternatives for companies. The problem in this regard is whether the company is able to choose the appropriate type of product for their pipelines. Hence, the efficiency of the inhibitors is on the line whereas the market offers a considerable number of competitors are vying for their attention. Studies have indicated the need to measure inhibitor efficiency and ensure the height in quality such elements.
Before the application of the inhibitors on the pipelines, studies have noted the importance of evaluation of these corrosion inhibitors to make sure that the assets of the company are protected. Several tests should be carried out in order to weed out the more incongruous nominees. This is to make sure that the final choices will not include any poor performing corrosion inhibitor. In this regard, companies have to test these alternatives individually to get first hand data on the matter.
Articles on corrosion inhibitors cover certain types of test that could be used on inhibitors. For instance, one study motioned to testing the transportability of the inhibitor. This means that the test will determine whether an inhibitor is soluble in either oil, in water, and/or but not limited to both. Studies have shown that those categorised as organic inhibitors are more soluble than the rest especially when made in contact with aromatic hydrocarbons.
Another means of studying the inhibitor is by measuring the corrosion protection of the material. For instance, there are reports that point to the measurement of film persistence. In this type of test, the metal is bared on the reserved test solution for a provided number of times. The consequent corrosion is then monitored including the number of rinses per hour and the filming solution itself. Another form of testing the quality of the corrosion inhibitors is by metal loss. This aspect of corrosion is measured by means of gravimetric and radiometric methods. These methods are effective in measuring the occurrence of localised corrosion particularly pitting corrosion and attacks in the crevices of the pipelines.
Prevention and Remedial Actions
The discussion in this paper presents several new technologies that serve to prevent corrosion of the external parts of pipelines. Though such existence add up to the overall efficiency of corrosion control, effective corrosion control is still achieved through traditional preventive approaches which has been tried and tested by veterans in the petroleum and petrochemical industry. Studies have shown that corrosion management is only as good as the length at which the company can maintain a certain level of quality in its implementation. Following this line of reasoning, a company would require funds to address this area, hence the company requires knowledge of the actual costs on which savings could be consequently acquired. In this manner, the company would be able to have some form of financial flexibility and in the same manner, find ways to maintain a level of corrosion management that would guarantee the maximisation of the operational lives of their pipelines.
In the same manner, the discussions above have also provided a veritable argument against the longstanding myth about corrosion. It has been accepted in the past that pipelines are made of metals and thus would have a natural course of deterioration which is normally caused by corrosion. Added to this is the notion that there is nothing that can be done to address this natural progression. As seen in the discussions above, the process of corrosion could be limited and even significantly minimised just by applying certain chemicals, choosing the appropriate materials, and even running a live current through the material.
Thus, the effectiveness of corrosion maintenance done within a company is implemented in its optimal level when the policies and standards of the company itself complement the ends of its intention to prolong the lives of its pipelines. The financial aspect as well as the operational facets of the company should thus mesh so as to guarantee that it would be able to achieve its ultimate goals.
Chapter 5
Summary, Conclusion and Recommendations
The previous chapters have discussed all of what was acquired during the acquisition of the data. This has been presented in the description of the topic, the review of related literature, the methodology, as well as in the presentation, interpretation and analysis of the findings of the research. This chapter shall sum up all the arguments and observations provided in the earlier chapters. This chapter shall be divided into three parts. The first part shall present a summary of the findings. The second part shall establish the overall conclusion of the research based on the earlier arguments, observations and summary provided in this chapter. The last part of this chapter shall be a ser of recommendations. This shall constitute those that may serve a better purpose for the readers of this study, especially those directly connected with corrosion management of petroleum and petrochemical pipelines.
SummaryThe crux of the dissertation is basically an analysis of corrosion, its composition and implication on metal surfaces, especially in pipelines. The study has defined corrosion as the slow degradation and deterioration of materials by the very chemical contact with other elements and their environment. The implications of corrosion are also taken into account in the previous chapters. Based on the discussions, it appears that for every type of equipment or material there is a different way of reacting to the elements. In any case, the implications of corrosion in pipelines are essentially adverse as it translates to wastage, loss of revenue, and even degradation of the ecosystem. Damages on these properties tend to entail expensive alterations or replacements regardless of the extent of the corrosion.
The discussion in the previous chapters has maintained other implications of corrosion if the company fails to manage it effectively. For instance, corrosion tends to reduce the thickness of the metal pipes which essentially implies loss of the strength and structural integrity. More so when the corrosion takes place on localised spots in the material. The weakening of the metal is imposed in the instance that such localised corrosions like pitting and crevice corrosion occur. Aside from the financial implications of corrosion, the employees that directly work on these structures are openly at risk as they would be the first to be subjected to the actual implications in the onset of leaks or other more disastrous implications.
The discussions above also implied that the product that moves through the pipes would also be affected immensely. For one, these fluids would be contaminated to some extent. As a result, this contamination as occurred by the corrosion of the conduits reduced the value of the product as it has become polluted in some manner.
The consequent perforation of pipes, especially those connected t petroleum and petrochemicals tend to show a considerable magnitude of risk especially for the environment. This is particularly accurate on instances where the pipelines go through a channel of marine water. It is an accepted fact that saltwater is inevitably aggressive in the process of corrosion as it is subjected to surfaces of metals. It must also be indicated that it works both ways. Damage is not limited to the environment as the corrosive component of the external environment tends to trigger some form of internal corrosion and even compromising the overall composition of the product.
In terms of the operations of the company, the implications of corrosion is not only limited to the metallic element of the pipelines. It adds up to the total inefficiency of the operations once corrosion sets in. An instance pointed out early on is the possibility of adding frictional and other bearing properties in the process. This basically means that the flow of petrochemical and petroleum in these pipes will significantly diminish in rate once affected by corrosion. There are also instances that the conductivity of these metals diminishes as well as the transfer of heat that emanates from the surface of these pipes.
The discussions in the previous chapters also pointed out that corrosion doesn’t limit itself on the surface of the pipes alone. Crevices of the pipe where screws and other areas such as the pumps and the valves tend to explicitly affect the operations adversely. On the whole, the inability of the company to manage its pipelines adds up to the overall complication on the operations particularly with the equipment used in its operations. If the company did not undertake any initiative prior to the use of these pipes to protect it from corrosion or at least ensure that the operational life of these pipes are prolonged, then it is up for a whole lot of replacing, repairing, and loss.
ConclusionCorrosion could be triggered by a considerable amount of causes. When there are well established areas in the surface of the pipe for the reactions of both anodic and cathodic elements. This focuses the damage of the pipes on a minute area of the surface which could subsequently trigger a much larger and more serious damage in the long run. This is especially possible in instances where the elements in the pipes are of differing electrochemical property. As indicated in the earlier chapters, this is noted as a galvanic effect. Upon contact, these items which possess noble and basic potentials tend to induce undue deterioration by virtue of corrosion. The effects of that notably increase the possibility of attracting impurities such as rust, dirt and even induce stress. More importantly the effects of this kind of corrosion are concentrated in the place where the galvanic couple come into contact.
The discussions in the previous chapters also implied that the stimulation of anodic and cathodic reaction increases the possibility of corrosion in pipelines. The formation of certain oxide films that protect the surfaces of these metal pipes tend to limit its capability in the instance when elements like chloride and other aggressive ions comes into contact with these items. In the same manner, these elements are based primarily on the actual environment on which the pipeline is subjected. For instance, those that are submerged in seawater tend to accumulate sodium chloride while the effects of icing during winter tend to deposit moisture in certain crevices on these pipelines.
In any case he study has given not only the adverse effects of corrosion in pipelines and the implication on the company, the study have also taken steps to highlight the importance of actual prevention on these assets. The subsequent parts of this chapter shall be pointing out certain suggestions on the overall prevention of the pipeline corrosion in the industry. From simple acquisition of top quality material to the more complex monitoring processes, companies have to take this in hand so as to guarantee the protection of the merchandise of flowing from these pipes, the efficiency of the operations of the company, and the reduction of significant losses for the petrochemical and petroleum industry all over the world.
RecommendationsThe study basically, having a rather descriptive temperament intends to show what the current situation in pipeline management and consequently seeks to provide recourse for companies. Hence, this study leans more towards the prevention of corrosion than the actual maintenance of pipelines. However, this does not mean that this study implies that companies limit itself to the activities prior to the use of such pipelines. This study suggests that companies could maximise the use of such pipelines by choosing the best possible items available at their disposal and consequently keeping track on how these pipelines contend with the existing environment. All in all, companies could carry all these out by merely extending the lifeline of these items. In order to realise this, the following proposals come to mind:
· Provide utmost conditioning on the metal used for pipelines
As discussed in the earlier parts of this study, the metal ultimately spells whether it shall operate for a long time or if it will succumb to deterioration at a faster extent. The earlier chapters noted the effectiveness of coating the surface of the metal. This is to impose some resistance to corrosion by placing some form of covering or shielding effect from the corrosive elements. Earlier chapters pointed out the possibility of using another metal to coat the actual pipes. Normally, tin and zinc are used to make sure that steel pipelines are safe from the elements. Other protective coatings are derived from organic coatings. These are essentially found in resins and other paint-like substances. These essentially deflect any form of impurity that triggers corrosion. It interposes a barrier from between the actual component of the metal to the elements of the environment. As discussed in the previous chapters, some of these coating could possess some inhibitors to specific types of damaging elements. Another alternative is to alloy the metal. This is done to protect the pipes from the elements but instead of using actual non-metal inhibitors, a thin layer of metal plate is employed. This process is seen in the use of chromium and nickel in stainless steels.
· Closely analyse the corrosive environment
The study also recommends conditioning the surroundings on which the pipeline is situated. For instance, the pipelines that are in an environment that could be controlled by the company would benefit from this recommendation. If it is submerged in a controllable environment, then the company could attempt to remove the oxygen to achieve a pH level that would considerably diminish the possibility of corrosion. An accepted element used as a reducing agent of oxygen is sulphite. The recurring problem in this recommendation is that it would not present any practical recourse on the company as it will have to continually go through the process of imposing reducing agents on the water on a regular basis. Thus, the process may cost more than that of the actual replacement of a damaged pipeline.
Another possible course of action is to use corrosion inhibitors in the process. These are essentially chemicals that are added in the corrosive environment of the pipeline, will reduce the possibility of metal deterioration induced by corrosion. The company could choose from a wide array of options. They could use anodic inhibitors which, as the name implies, impedes with the anodic processes. The issue on this inhibitor is that all the elements should be present otherwise it will essentially add up to the corrosion process instead of actually helping. A less dangerous inhibitor is the cathodic types. Basically, they reduce the area on which cathodic reaction could actually ensue. Unlike the earlier one recommended, this type of inhibitor does not amount to any possibility of concentrated localised corrosion. Companies also have the option of using these two processes, anodic and cathodic. This requires the process to consider the synergy of the chemical composition of the material and the ions present in the accessible environment.
· Attempt to the controlling the processes electrochemically
Based on the discussions in the previous chapters, the process of corrosion is entirely electrochemical. This means that corrosion will essentially take place in time through the actual potential of the metal. This means that there is also the possibility that ions of the material comes into play. Corrosion could thus be avoided by applying anodic or cathodic currents into the metal. In its simplest sense, passing though a charge that is totally the opposite of the corrosive elements in the environment signifies that it would be repelled by the actual pipeline. Though it would not entirely eliminate the possibility of contact, the process is significantly slowed down to a certain extent.
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