Study on AC Stray Current Corrosion Law of Buried Steel Pipelines

2012 ◽  
Vol 263-266 ◽  
pp. 448-451 ◽  
Author(s):  
Xin Hua Wang ◽  
Guo Yong Yang ◽  
Hai Huang ◽  
Zhenhua Chen ◽  
Li Mei Wang
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Current Density ◽  
Transmission Lines ◽  
Buried Pipelines ◽  
Safe Operation ◽  
Stray Current ◽  
Soil Resistivity ◽  
Ac Current ◽  
The Impact

AC stray current can cause AC corrosion and destroy the safe operation of buried pipelines, which comes mainly from nearby high voltage transmission lines and AC electric railway. The research and evaluation lags far behind DC stray current at home and abroad, besides, the AC current density measuring procedures are complex. Through experimental study of different parameters on the impact of the AC current density established a mathematical model of damaged area, soil resistivity, pipe-to-soil potential and coating resistivity. With it can indirectly get the AC current density, which improve efficiency by simplifying the measuring procedures. Also, provide a basis for harmfulness evaluation of AC stray current by studying the impact of AC current density on the corrosion rate.

A Real-Time AC/DC Measurement Technique for Assessment of AC Corrosion of Buried Pipelines

2012 ◽  
Author(s):  
Cindy X. Su ◽  
Luyao Xu ◽  
Frank Y. Cheng
Keyword(s):  
Real Time ◽  
Current Density ◽  
Steel Surface ◽  
Steel Corrosion ◽  
Buried Pipelines ◽  
Total Potential ◽  
Ac Current ◽  
Potential Alternative ◽  
Current Densities ◽  
Ac Interference

In this work, a real-time AC/DC signal data acquisition (DAQ) technique was developed, which is capable of separating the DC and AC potential components from the recorded total potential, providing mechanistic information about the steel corrosion in the presence of AC interference. It was found that the corrosion of the steel is enhanced by the applied AC current density from 0 to 400 A/m2. With the further increase to 600 A/m2 and 800 A/m2, the corrosion rate of the steel decreases, which is attributed to passivation of the steel at sufficiently high AC current densities, and a compact film is formed on the steel surface. Moreover, the derived mathematic relationships between AC potential and AC current density provides a potential alternative to determine AC current density on pipelines based on measurements of AC potential in the field.

Experimental Study on GH3536 Surface Discharge Mark Diameter of EDG

2013 ◽  
Vol 664 ◽  
pp. 817-820 ◽  
Author(s):  
Ji Gao ◽  
Di Wang ◽  
Yao Sun
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Empirical Formula ◽  
Pulse Width ◽  
Orthogonal Test ◽  
Regression Equation ◽  
Surface Discharge ◽  
Test Analysis ◽  
Peak Current ◽  
The Impact

This article using the method of orthogonal test analysis the law of honeycomb ring part in aero-engineer surface discharge mark diameter by EDG. In the impulse voltage under certain conditions,by changing the peak current and pulse width in the interelectrode study both of the impact of the largest diameter of GH3536 surface discharge mark, and build a mathematical model of the regression equation, derive relatively accurate empirical formula. Provide a good reference and guidance for the actual production of the EDG.

Effects of alternating stray current on the corrosion behaviours of buried Q235 steel pipelines

2017 ◽  
Vol 64 (6) ◽  
pp. 599-606 ◽  
Author(s):  
Yanbao Guo ◽  
Hai Tan ◽  
Deguo Wang ◽  
Tao Meng
Keyword(s):  
Corrosion Rate ◽  
Current Density ◽  
Corrosion Potential ◽  
Rapid Development ◽  
Geometrical Shape ◽  
Uniform Corrosion ◽  
Negative Deviation ◽  
Stray Current ◽  
Content Type ◽  
Ac Current

Purpose With the rapid development of rail transportation and energy-delivery systems, such as buried oil and gas pipelines and high-voltage transmission lines, the alternating current (AC) corrosion of buried steel pipelines is becoming more serious. This paper aims to study the corrosion behaviours of Q235 buried steel pipelines induced by the alternating stray current, with a set of indoor simulated experiment apparatuses. Design/methodology/approach The corrosion of the coating holidays of the buried steel pipelines at various AC current densities from 0 to 200 A/m2 in the soil-simulating environment was revealed by the electrochemical and weight-loss methods. Findings The results showed that the corrosion potential of the steel shifted negatively obviously and the corrosion rate of the steel increased with the increasing of AC current density. At a low AC current density, the negative deviation of the corrosion potential of the steel was small and the increase of corrosion rate was slight. However, the negative deviation of the corrosion potential was remarkable and the corrosion rate was greatly increased at a relative higher AC current density. The geometrical shape of the corrosion images indicated the corrosion forms changed from uniform corrosion to local corrosion due to the increase of AC interference. Originality/value Investigation results are of benefit to provide a new strategy to forecast and evaluate the AC-induced corrosion of the buried pipelines which could improve the safety of pipeline transportation.

scholarly journals Numerical modelling of buried pipelines under DC stray current corrosion

2019 ◽  
Vol 9 (2) ◽  
pp. 125-134 ◽  
Author(s):  
Yaping Zhang ◽  
Qiong Feng ◽  
Lianqing Yu ◽  
Chi-Man Lawrence Wu ◽  
Siu-Pang Ng ◽  
...  
Keyword(s):  
Environmental Problem ◽  
Three Dimensional ◽  
Corrosion Process ◽  
Comsol Multiphysics ◽  
Buried Pipelines ◽  
Stray Current ◽  
Soil Resistivity ◽  
Intensity Changes ◽  
Dimensional Equation ◽  
Corrosion Mechanisms

Corrosion of buried pipelines caused by stray currents is becoming a serious industrial and environmental problem. It is therefore necessary to study corrosion mechanisms of buried pipelines under DC stray currents in order to propose effective anti-corrosion measures. Since measurement of the potential is one of important ways to identify stray current intensity, the COMSOL Multiphysics software was used to simulate stray current corrosion dynamics of buried pipelines. It was also used to calculate the distribution and intensity changes of electrolyte potential in the cathodic protected system by solving Laplace’s three-dimensional equation. The obtained results showed that increased applied voltage leads to more positive shift of a pipeline potential, resulting in acceleration of stray current corrosion. On the contrary, increased soil resistivity can retard the corrosion process. The protected pipeline with a sacrificial anode suffers less corrosion interference than unprotected pipeline. Two crossed arrangement of pipelines makes no difference in corrosion of protected pipeline, but affects greatly on unprotected pipeline.

Experimental Study on the Wet Molding for Wheat Straw Pellet Fuel

2010 ◽  
Vol 156-157 ◽  
pp. 284-292 ◽  
Author(s):  
Jian Jun Hu ◽  
Quan Guo Zhang ◽  
Ting Zhou Lei ◽  
Zhi Wei Wang
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Plastic Deformation ◽  
Linear Equation ◽  
Wheat Straw ◽  
Elastic Deformation ◽  
Moisture Ratio ◽  
Transitional Stage ◽  
Exponential Equation ◽  
The Impact

In the paper, in order to investigate the situation of impact on wet molding for straw of compressing speed and moisture ratio, and look for the inside law between them, closed compress experimental study on the wet molding for wheat straw pellet fuel was done by electrical universal material experimental machine and experimental provision made by oneself. Study on the impact situation for compressing speed and moisture ratio was done from pressure intensity, displacement and density of materiel. The result, which low compressing speed and low moisture ratio were propitious to wet molding, was gotten. The molding stage can be divided to loose stag, transitional stage, compressing stage. Partial elastic deformation mainly occurred In loose stage, and its mathematical model was linear equation. Elastic deformation mainly occurred In transitional stage, and its mathematical model was exponential equation. Plastic deformation mainly occurred In compressing stage, and its mathematical model was linear equation. The conclusion above has general directive significance to wet molding for straw pellet fuel.

scholarly journals Research Advances of Soil Corrosion of Grounding Grids

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 513
Author(s):  
Cheng Zhang ◽  
Yuxiang Liao ◽  
Xue Gao ◽  
Jing Zhao ◽  
Yuan Yuan ◽  
...  
Keyword(s):  
Power System ◽  
Safe Operation ◽  
Stray Current ◽  
Protective Measures ◽  
Soil Corrosion ◽  
Grounding Grid ◽  
Detection Technology ◽  
Grounding Grids ◽  
The Impact

A grounding grid plays the role of discharging current and balancing voltage to ensure the safety of the power system. However, soil corrosion can damage the grounding grid, which then can endanger the safe operation of power system. This paper reviewed recent research advances of soil corrosion of grounding grid. The cause, mechanism, types, and influencing factors of soil corrosion of grounding grids were summarized, and the corresponding detection technology and protective measures were also introduced. The paper pointed out that soil corrosion is a serious threat to the grounding grid system. Moreover, the impact mechanism of AC stray current, new corrosion detection technology, and better protective measures still need in-depth research.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

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