File Name: external corrosion and corrosion control of buried water mains .zip
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Corrosion and cathodic protection CP are electrochemical phenomena. Understanding corrosion and CP requires a basic knowledge of chemistry and electrochemistry. Electrochemistry is a branch of chemistry dealing with chemical changes that accompany the passage of an electric current, or a process in which a chemical reaction produces an electric current.
Norsworthy, Richard. As important as cathodic protection is to external corrosion control, it may not be the most important issue facing those concerned with preventing external corrosion. The NACE International SP document clearly states the intent of the document is to provide guidance for effective control of external corrosion.
In order to ensure smooth and uninterrupted flow of oil and gas to the end users, it is imperative for the field operators, pipeline engineers, and designers to be corrosion conscious as the lines and their component fittings would undergo material degradations due to corrosion. This paper gives a comprehensive review of corrosion problems during oil and gas production and its mitigation. The chemistry of corrosion mechanism had been examined with the various types of corrosion and associated corroding agents in the oil and gas industry. Factors affecting each of the various forms of corrosion were also presented. Ways of mitigating this menace with current technology of low costs had been discussed. It was noticed that the principles of corrosion must be understood in order to effectively select materials and to design, fabricate, and utilize metal structures for the optimum economic life of facilities and safety in oil and gas operations. Also, oil and gas materials last longer when both inhibitors and protective coatings are used together than when only batch inhibition was used.
Corrosion of metallic pipelines is a significant source of failures and a financial burden to drinking water utilities. A large portion of drinking water infrastructure is reaching the end of its useful service life. In the United States, the annual total of water main breaks attributed primarily to corrosion was estimated as , breaks per year. As part of an ongoing Water Research Foundation project WRF , technical and economic considerations for cathodic protection CP installation and retrofit of buried water pipelines have been investigated to generate a best practice guide tailored for water utilities. CP of metallic structures is commonly achieved by galvanic protection or impressed current protection, depending on the specificities of the system. The basic concept behind CP is that applying current in the form of electrons or charged ions to a metallic surface can reduce the tendency of metallic ions to separate from the parent structure usually in the form of oxides. In the United States, CP is required by regulation for gas pipelines and hazardous liquid interstate pipelines installed after the early s.
The sacrificial metal then corrodes instead of the protected metal. For structures such as long pipelines , where passive galvanic cathodic protection is not adequate, an external DC electrical power source is used to provide sufficient current. Cathodic protection systems protect a wide range of metallic structures in various environments. Common applications are: steel water or fuel pipelines and steel storage tanks such as home water heaters ; steel pier piles ; ship and boat hulls; offshore oil platforms and onshore oil well casings; offshore wind farm foundations and metal reinforcement bars in concrete buildings and structures. Another common application is in galvanized steel , in which a sacrificial coating of zinc on steel parts protects them from rust. Cathodic protection can, in some cases, prevent stress corrosion cracking. Cathodic protection was first described by Sir Humphry Davy in a series of papers presented to the Royal Society  in London in
Gan, Z. Sun, G. Sabde, D. A study was conducted to determine the feasibility of cathodically protecting the steel surface beneath a disbonded coating with a holiday using an external power source. The local pipe potential and solution pH within the crevice of the disbonded coating during cathodic protection were measured over time. The relative advantages of using a pulsed current PC vs those of a direct current DC were examined. Results indicated applied cell voltage was an important factor for proper protection of a coated steel pipe in high-resistivity soils.
American Water Works Assoc. Andrew E. Romer , Graham E. Bell , Steven J. Duranceau , Scot Foreman. Water utilities often do not know the specific cause of external corrosion observed on their water mains, and consequently, the chosen preventative measure may not work effectively.
Strategic management dictates that the arrangement for corrosion control and monitoring should be made during project construction. Contractual obligation cannot absorb such a cost. Emenike, C. Report bugs here. Please share your general feedback.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The offshore pipeline industry, since its first ventures into the Gulf of Mexico and the waters off California more than 40 years ago, has steadily improved its operating practices, with new materials, more robust designs, and more efficient techniques for construction, operation, and maintenance.
Именно он и подал ручную команду на отзыв Следопыта. Вопрос насколько. уступил место другому - с какой целью?.
- Хватит валять дурака. Какой-то тип разыскивал Меган. Человек не выпускал его из рук. - Да хватит тебе, Эдди! - Но, посмотрев в зеркало, он убедился, что это вовсе не его закадычный дружок. Лицо в шрамах и следах оспы.
Первая неделя оказалась последней. Солнечный удар и инфаркт. Бедолага.