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Under normal conditions, there are different protection objects inside and outside the gas station, so two sets of independent cathodic protection systems are adopted. At the same time, an insulating flange is applied at the position where trunk pipelines access to the gas station, which realizes electrical isolation of the structures inside and outside the station. However, as a result of short distance between the two cathodic protection systems, there will be stray current interference between them. The purpose of this paper was to study on the interference between cathodic protection systems of gas station and long distance trunk pipeline.

Based on the above, in this paper, first, the mathematical model of interference between cathodic protection systems was established and the control equations solved using the boundary element method. Second, the influence of cathodic protection system of gas station on long distance trunk pipeline and the influence of cathodic protection system of long distance trunk pipeline on gas station were studied separately using BEASY software. Finally, a new thought of cathodic protection design for local station was put forward.

It was concluded that there were serious interference problems between the cathodic protection systems of gas station and long distance trunk pipeline. By moving the potential control point to area outside the influence scope of anode ground bed could avoid the influence of cathodic protection system of gas station on long distance trunk pipeline. By moving the auxiliary anodes away from gas station could avoid the influence of cathodic protection system of long distance trunk pipeline on pipelines in gas station. The new thought of cathodic protection design could avoid the interference between the cathodic protection systems effectively.

It is considered that the results can guide cathodic design for gas station and long distance trunk pipeline. The results can also avoid the interference corrosion between the structures in gas station and trunk pipeline.

The purpose of this investigation was to study these problems and design regional cathodic protection, using numerical simulation. Regional cathodic protection technology is immature at home and abroad. This is reflected in the fact that in gas stations, there are many underground pipelines, which can lead to serious interference and shielding phenomena, and there are many grounding networks that can cause substantial loss of the cathodic protection current.

Based on the above, in this article, first of all, the mathematical model of the buried pipeline cathodic protection potential distribution was established and the control equations solved using the boundary element method. Second, the cathodic shielding effect in pipeline concentration areas, the effect of instrument equipment grounding systems on cathodic protection and the influence of DC stray current on the interference of pipeline corrosion were studied separately using BEASY software. Finally, the BEASY software was used for a regional cathodic protection design for a real gas station.

It was concluded that impressed current used in combination with sacrificial anodes for regional cathodic protection design is often the most economic and effective approach. However, the output current of the auxiliary anode is large with high energy consumption. In consequence, it may be recommended that the station pipelines should be laid on the ground, rather than under it.

It is considered that the results can guide regional cathodic protection design for real-life installations very well.

The aim of this paper is to present the modernization of an old cathodic protection system installed on the legs of an offshore platform and to discuss the results of the research performed in order to investigate the anticorrosive effectiveness of this solution.

The modernization of the cathodic protection system consisted of connecting to the platform legs a sacrificial anode system placed at the sea bottom. The effectiveness of the modernized system was assessed on the basis of the measurements of the potential profiles of the platform legs, i.e. the distribution of their potential over the entire length.

After connecting sacrificial anode systems, the potential of the legs kept changing towards more negative values. The extent of cathodic polarization increased, and already after a week the potential of the legs fell within the range of full cathodic protection almost along their entire length. The polarization was higher at the lower parts and decreased close to the water surface, which was a result of the distance of a given fragment from the anodic system. The results of the measurements confirmed the correctness of the design assumptions and the effectiveness of the performed modernization.

The results obtained show that the modernization of the cathodic protection system on the legs of an offshore platform consisting of connecting sacrificial anode systems placed at the sea bottom can ensure the achievement of full cathodic protection potential for long legs (these were 80 m long in this study).

The corrosion problem of the tank bottom plate is growing more and more obvious as the usage period of the tank increases. The purpose of this study is to explore the specific effects of various factors on the potential distribution of the tank bottom plate and propose reasonable cathodic protection measures for tanks through simulation and indoor tests.

In this paper, several aspects (such as anode conditions, soil resistivity and so on) impacting the potential distribution of the tank bottom plate are explored by means of indoor tests and MATLAB software simulations, and the related results are presented using Origin software plots.

The results show that the potential value of the tank bottom plate is positively shifted with the increase of anode well depth and distance and the decrease of output current, and the overall potential distribution uniformity is higher; the anodic well output current has the greatest influence on potential distribution; to set up regional cathodic protection in the multitank area, the anodic well should be arranged in the central position between multiple tanks. Regional cathodic protection potential distribution for multiple anodes is more uniform, but a reasonable number of anodes should be selected, usually 2–3 anodes.

This paper provides solid theoretical and technical support for the future establishment of cathodic protection systems in station yards, as well as the renewal and transformation of cathodic protection systems in old tanks, by investigating the influencing factors on the potential distribution of tank bottom plate and verifying them through indoor experiments.

Irrespective of the type of cathodic protection system applied to an offshore platform or pipeline the longevity and effectiveness of that system, and therefore the safety and continued revenue earning capacity of the platform or pipeline, can be assured only if adequate monitoring and surveying of the performance is undertaken.

Cathodic protection by galvanic or impressed current techniques is probably the most favoured method of obviating the corrosion of buried and immersed metals. The theoretical principles and the economics involved in such protection are well established now and have been the subject of numerous papers, monographs and reviews. Cathodic protection is, however, still far from being an infallible method of corrosion prevention primarily because (a) the cathodic protection conditions necessarily change with the environment, (b) complete corrosion protection is rarely achieved in practice (see below), and (c) corrosion of an apparently protected structure may occur through the presence of stray currents

In recent years, the demand for oil and gas pipelines has increased rapidly. Due to the restrictions of the pipeline routing, pipelines are generally laid in parallel or in the same trench, which results in stray-current interference between the independent cathodic protection (CP) systems. The purpose of this paper is to study the interference between the long-distance parallel pipelines and to obtain the optimized operation for the CP systems.

In this study, first, the numerical model of parallel pipelines was established using the boundary element analysis software (BEASY). Second, the effects of horizontal distance between parallel pipelines, coating damage rate, soil conductivity and anode output current on the interference of parallel pipelines were studied. Finally, by varying the layout or the output currents of CP stations, an optimized operation scheme osf long-distance parallel pipelines was put forward.

Simulation results showed that with a decrease in soil conductivity or coating damage rate, the interference increased. Moreover, the interference decreased with an increase in horizontal distance between two parallel pipelines or a decrease in anode output current. It was found that there are three methods to reduce the interference between long-distance parallel pipelines: to reduce the output currents of CP stations, combined protection and to close part of the CP stations. Among them, to close part of CP stations was the optimized scheme because of the lowest operating and maintenance cost.

The optimized operation scheme proposed in this study can not only solve the interference between parallel pipelines but also provide guidance for the parallel pipelines to be built in the future. Reasonably arranging the cathodic protection stations using numerical simulation can avoid the interference in the cathodic protection systems, and reduce the construction cost.

The purpose of this work is to provide theoretical guidance and experimental analysis for optimized cathodic protection (CP) design of low alloy steel in deep water environments.

In the present study, the CP criteria of 10Ni5CrMoV low alloy steel were investigated in a simulated deep water environment (350 m) regarding the theoretical protection potential and measured protection potential. The influences of hydrostatic pressure (HP) and temperature were also discussed in detail. The theoretical protection potential was analyzed with the Nernst equation, and the measured minimum protection potential was derived by extrapolating the Tafel portion of anodic polarization curves.

The results indicate that the minimum protection potential of low alloy steel shifts to a positive value in a deep-ocean environment. This can be attributed to the combined effects of HP and the temperature. Moreover, the temperature has a stronger influence compared with HP. The results suggest that the CP potential criteria used in shallow water are still applicable in the deep ocean, which is further confirmed through the SEM and x-ray diffraction analysis of the corrosion products resulted from the potentiostatic cathodic polarization experiments at −0.85 V_CSE.

In recent decades, successful applications of CP for long-term corrosion protection of the steel components applied at a subsea level have enabled the offshore industry to develop reliable and optimized CP systems for shallow water. However, differences in the seawater environment at greater depths have raised concerns regarding the applicability of the existing CP design for deeper water environments. Hence, this research focuses on the CP criteria of low alloy steel in simulated deep water environment concerning the theoretical protection potential and measured protection potential. The influences of HP and temperature were also discussed.

Reliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for substation grounding grids. The purpose of this paper is to consider the design proposal, installation, construction requirements and monitoring methods for Hunan 220 kV substation grounding grid.

This paper treated Hunan 220 kV substation grounding grid as a research object. The physical and chemical data of three soil samples were measured, German DIN50929 evaluation criteria were used to assess its corrosion and a sacrificial anode cathodic protection design was selected, based on advanced concepts.

The design proposal, installation, construction requirements and monitoring methods for the 220 kV substation grounding grid were clearly explained and recommended for implementation.

This paper has some guidance on design ideas and the selection method for substation sacrificial anode cathodic protection.

The presence of alternating current (AC) causes serious damage on buried pipelines even when the off potential matches the −0.85 V/CSE criterion. The optimum cathodic protection potential (OCPP) is more accurate for cathodic protection. The paper aims to study how to get the optimum cathodic protection by electrochemical impedance spectroscopy (EIS) and the effects of AC on the OCPP.

This paper describes the application of EIS to investigate the OCPP of X70 steel in a soil simulating solution with different AC interferences.

The experimental results indicate that AC interference makes the OCPP decrease and the −0.85 V/CSE criterion is not reasonable when there is AC interference. When the AC voltage is less than 6 V, the OCPP is approximately −900 mV/SCE, and when AC voltage is more than 7 V, the OCPP is roughly −1,000 mV/SCE.

There have been some researches on the OCPP, and the paper is the first one to study the AC effects on the OCPP and found that the OCPP changed when there was AC interference.