Deep Water Cathodic Protection: Part 2—Field Deployment Results

Chen, S.; Hartt, William H.; Wolfson, Steve L.

doi:10.5006/1.3277601

Cited by 43 publications

(19 citation statements)

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“…Some natural ocean tests were reported by American [1][2][3][4], Russian [5,6], and Indian [7,8]. They revealed that materials undergo serious corrosion in deep ocean.…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrostatic pressure on the nature of passive film of pure nickel

Liu

Zhang

Shao

et al. 2011

Materials & Corrosion

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The effect of hydrostatic pressure on the nature of passive film of nickel in 3.5% NaCl solution was investigated by means of polarization curves, electrochemical impedance spectroscopy (EIS), and Mott-Schottky measurement. The experimental results revealed that hydrostatic pressure had two opposite effects on passive film of nickel. On one hand, hydrostatic pressure improved the corrosion resistance of passive film of nickel such as the decreased acceptor density. On the other hand, the passive film became unstable and showed a higher diffusivity of acceptor density with the increasing of hydrostatic pressure, which deteriorated the corrosion resistance of passive film of nickel. The deterioration effect had greater influence on the passive film than the improvement effect, which led to the decreasing corrosion resistance of passive film with the increasing of hydrostatic pressure.

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“…Some natural ocean tests were reported by American [1][2][3][4], Russian [5,6], and Indian [7,8]. They revealed that materials undergo serious corrosion in deep ocean.…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrostatic pressure on the nature of passive film of pure nickel

Liu

Zhang

Shao

et al. 2011

Materials & Corrosion

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“…− κ l ∂ E l ∂n l 4,5,6,7 = κ r ∂ E r ∂n r 4,5,6,7 [7] and E l | 4,5,6,7 = E r | 4,5,6,7 [8] The boundary 4,5,6,7 refers to the electrolyte-filters interfaces in the model of Fig. 1.…”

Section: Numerical Modelingmentioning

confidence: 99%

Finite Element Modeling for Cathodic Protection of Pipelines under Simulating Thermocline Environment in Deep Water Using a Dynamic Boundary Condition

Sun

et al. 2013

J. Electrochem. Soc.

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A finite element model (FEM) was established to calculate the cathodic protection (CP) potential distribution on pipelines, under the environment of the thermocline structure in deep water. Supplemental boundary conditions were applied on the interfaces of two different mediums in the thermocline model. To solve the problem of time-dependent polarization curves due to calcareous deposits formed on the steel surface during CP in seawater, a dynamic boundary condition based on Ohm's law was proposed, instead of polarization curves or the Butler-Volmer equation. A good agreement was obtained between the calculated and experimental potential distributions, which proved that the model was practical and feasible. The anode placement studies revealed that the anode could supply a more efficient protection when it was placed at the thermocline zone rather than the surface zone or the deep water zone.Cathodic protection (CP) is one of the most effective methods for decreasing the corrosion of offshore structures and pipelines in seawater. There are two methods to supply direct current for CP systems, impressed current CP systems and sacrificial anode CP systems. Impressed current is usually supplied by a rectifier, which converts alternating current from the power lines to direct current. In a sacrificial anode CP system, single or multiple anodes distribute the cathodic current to the protected structure. 1 Numerous national, international and commercial standards have been published for the CP design of offshore structures at present. [2][3][4] Oil and gas production is now rapidly moving into deep water, which introduces significant changes in the chemical and physical properties (pressure, temperature, dissolved oxygen, etc.) that can influence CP processes. Therefore, a number of laboratory and field studies have been performed to investigate the influence of deep water properties on CP processes. 5-12 Compared with pressure, temperature plays a much more significantly influential role in CP, and most chemical and physical properties of seawater like dissolved oxygen depend on it. 6,13-15 Moreover, temperature observably affects the formation of calcareous deposits, which are important to an efficient CP system. [16][17][18][19] The profile of temperature in deep water can be described in the terms of thermocline structure, which consists of three layers: the surface zone, the thermocline zone and the deep zone, respectively. 11,12 Here the surface zone represents the surface water of the ocean with the highest temperature. Separating the deep zone from the surface zone is the thermocline zone, where the temperature changes abruptly with the depth. The temperature shift in these zones can lead to different polarization behaviors of materials. When offshore structures like pipelines or oil and gas well casings are passing through the thermocline environment, different parts of offshore structure in different layers will be galvanically coupled which can influence the CP on the entire structure. Therefore, in order to ...

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“…Where average molecular mass of Fe-20Cr alloy is 55.15 g/mol, Faraday constant is 9,6500, and density of Fe-20Cr alloy is 7.5 g/cm 3 . The largest pit sizes within each of the potentiostatic measurements were calculated and the values were subjected to extreme value statistics analysis.…”

Section: Volume (Cm 3 ) =mentioning

confidence: 99%

“…Some natural ocean tests were reported by American [1][2][3][4], Russian [5,6] and Indian [7,8]. They revealed that materials undergo serious corrosion in deep ocean environment.…”

Section: Introductionmentioning

confidence: 95%