2.2.5 INTERNAL CORROSIONS
Pipe wall is exposed to water and contaminants in the gas, such as O2, H2S, CO2, or chlorides can lead to corrosion on the internal wall of hydrocarbon process systems. The nature and extent of the corrosion destruction that may occur are functions of the concentration and particular combinations of these various corrosive elements within the pipe, as well as of the operating conditions of the pipeline. For example, corrosion damage may occur from effect of gas velocity and temperature in the pipeline play a significant role in determining if and where. In other words, a particular gas composition may cause corrosion under some operating conditions but not others ...view middle of the document...
The types of morphology of the carbon dioxide (CO2) corrosion are localized thinning and/or pitting corrosions style. Carbon dioxide (CO2) corrosion usually attack carbon steel pipe works. Because of the types of flow such as turbulence flow, carbon steel may suffer from severed pitting and grooving at these areas. Moreover, corrosion commonly occurs in areas of turbulence and impingement and sometimes at the root of the piping welds (Cescor, 2010)
Figure 9 : Carbon dioxide (CO2) corrosion of carbon steel pipe nipple in CO2 contaminated water
By compensate corrosion allowance for the wall thickness loss; the corrosion caused by carbon dioxide (CO2) may be controlled. Other than that, the injection of chemical treatment for corrosion mitigation, the application of organic or metallic linings or the use of integrally corrosion resistant materials also can be used for corrosion controlled. Selections of the best materials need to be considered if the volume of the carbon dioxide (CO2) in the production fluid is high. Because of this high corrosivity of the carbon dioxide (CO2) to water phased was the main reason for selection of corrosion resistant alloys (CRA) materials rather than choosing carbon and low alloy steel (CLAS) in the application of facilities or systems that handling production fluid which need to be decided at the design stage ( Cescor, 2010)
18.104.22.168 Microbiologically Induced Corrosion (MIC)
Biological organisms (microbes) can influence corrosion in the oil and gas pipelines. This type of corrosion can be severed if not controlled or monitored. Primarily, the only concern is that this "influence" often results in an extremely accelerated rate of corrosion (Huggins, 2014) By-products that cause corrosion are bacteria colonies embrace nutrients from the environment. There are about tens of bacteria that cause this type of corrosions. Oxidation agent for assimilation of organic matter, and sulphur oxidisers, that oxidise sulphides to sulphates, and finally sulphuric acid are by the most common bacteria which are sulphate reducers or sulphate reducing bacteria “SRB” that use the sulphate ion (Cescor, 2010)
Microbiological corrosion is conveyed in the oil industry in storage tanks, wet oil pipelines, water injection systems, hydrocarbon processing facilities, stagnant fire mains, and heat exchangers. They often occur in areas where conventional corrosion is thought to be under control and most problems are localised, resulting in pitting attacks. The corrosive attacks develop favourably under deposits, and are therefore more frequently met in low-flow conditions or stagnant dead-legs (Cescor, 2010)
According to Roland J. Huggins, in a general view, MIC can be in one of two groups based upon their oxygen necessities; one being aerobic (needs oxygen) such as sulfur oxidizing bacteria, and the other being anaerobic, (needs little or no oxygen), such as sulfate reducing bacteria. Other than that, microbial require water, a carbon...