Study on the interference between parallel pipelines and optimized operation for the cathodic protection systems

2019 ◽  
Vol 66 (2) ◽  
pp. 195-202
Author(s):  
Ziqing Yang ◽  
Gan Cui ◽  
Zili Li ◽  
JianGuo Liu
Keyword(s):  
Cathodic Protection ◽  
Maintenance Cost ◽  
Horizontal Distance ◽  
Output Current ◽  
Long Distance ◽  
Element Analysis ◽  
Content Type ◽  
Damage Rate ◽  
Protection Systems ◽  
Soil Conductivity

Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

Study on the interference between cathodic protection systems of gas station and long distance trunk pipeline

2016 ◽  
Vol 63 (5) ◽  
pp. 405-413 ◽  
Author(s):  
Gan Cui ◽  
Zili Li ◽  
Chao Yang ◽  
Xiaoyong Ding
Keyword(s):  
Cathodic Protection ◽  
Control Point ◽  
Protection System ◽  
Long Distance ◽  
New Thought ◽  
Content Type ◽  
Trunk Pipeline ◽  
Protection Systems ◽  
Gas Station ◽  
Cathodic Protection System

Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

scholarly journals Evaluation of Horizontal Electric Field from the Lightning Channel by Electromagnetic Field Equations of Moving Charges

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Yunfeng Zhang ◽  
Erchun Zhang ◽  
Jialiang Gu
Keyword(s):  
Electromagnetic Field ◽  
Electric Field ◽  
Finite Conductivity ◽  
Lightning Flash ◽  
Horizontal Distance ◽  
Field Equations ◽  
Long Distance ◽  
Return Stroke ◽  
Lightning Channel ◽  
Soil Conductivity

The horizontal electric field from the lightning return-stroke channel is evaluated by the electromagnetic field equations of moving charges in this paper. When a lightning flash strikes the ground, the charges move upward the lightning channel at the return-stroke speed, thereby producing the electromagnetic fields. According to the electromagnetic field equations of moving charges, the detained charges, uniformly moving charges, and decelerating (or accelerating) charges in each segment of the channel generate electrostatic fields, velocity fields, and radiation fields, respectively. The horizontal component of the sum is the horizontal electric field over the perfectly conducting ground. For the real soil with finite conductivity, the Wait formula is used here for the evaluation of the horizontal electric field over the realistic soil. The proposed method can avoid the oscillation of the fields in the long distance by the FDTD method and the singularity problem of the integral equation by the Sommerfeld integral method. The influences of the return-stroke speed, distance, and soil conductivity on the horizontal electric field are also analyzed by the proposed method. The conclusions can be drawn that the horizontal electric field decreases with the increasing of the return-stroke speed; the negative offset increases with the increasing of horizontal distance and with the decreasing of the soil conductivity, thereby forming the bipolar waveform. These conclusions will be practically valuable for the protection of lightning-induced overvoltage on the transmission lines.

The use of models for the design of pipeline cathodic protection systems

1969 ◽  
Vol 16 (3) ◽  
pp. 24-27
Author(s):  
Jirří Nekoksa
Keyword(s):  
Cathodic Protection ◽  
Power Supply ◽  
Protection System ◽  
Long Distance ◽  
Protection Systems ◽  
Piping Systems ◽  
External Power ◽  
Cathodic Protection System ◽  
Use Of Models ◽  
External Power Supply

THE INTENSIVE construction of long‐distance metal pipelines and of underground piping systems generally, has produced related problems in ensuring an effective cathodic protection system. For the cathodic polarisation of a protected construction, a cathodic protection installation with an external power supply is the most widely used.

Study on the interference corrosion of cathodic protection system

2015 ◽  
Vol 33 (5) ◽  
pp. 233-247 ◽  
Author(s):  
Gan Cui ◽  
Zili Li ◽  
Chao Yang ◽  
Xu Wei
Keyword(s):  
Cathodic Protection ◽  
Great Influence ◽  
Simulation Software ◽  
Protection System ◽  
Buried Pipelines ◽  
Stray Current ◽  
Damage Rate ◽  
Soil Conductivity ◽  
Cathodic Protection System ◽  
The Mathematical Model

AbstractDC stray current has a great influence on the corrosion of buried pipelines. In this article, first, we deduce the equation of DC stray current interference on pipeline and determine the corresponding boundary conditions. Second, we discretize the mathematical model with boundary element method. Third, the numerical simulation software BEASY is applied to study the interference corrosion of cathodic protection system. Five types of cathodic protection (CP) interference are considered, namely, anodic, cathodic, combined, induced, and joint interference. Moreover, the effects of different parameters on the degree of the CP interference are investigated. The results show that the degree of interference will decrease with the increase of soil conductivity; smaller coating damage rate will make interference more concentrated; anode parameters have a significant impact on anodic interference but have almost no effect on cathodic interference; for combined, induced, and joint interference, the likelihood for corrosion occurrence will be high at the current outflow point on pipeline.

Expected maintenance waste reduction benefits after implementation of Just in Time (JIT) philosophy in maintenance (a statistical analysis)

2019 ◽  
Vol 25 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Sandeep Phogat ◽  
Anil Kumar Gupta
Keyword(s):  
Data Interpretation ◽  
General Information ◽  
Spare Parts ◽  
Waste Reduction ◽  
Maintenance Cost ◽  
Just In Time ◽  
Content Type ◽  
Great Saving ◽  
Research Findings ◽  
Structured Questionnaire

Purpose The maintenance department of today, like many other departments, is under sustained pressure to slash costs, show outcome and support the assignment of the organization, as it is a commonsensical prospect from the business perspective. The purpose of this paper is to examine expected maintenance waste reduction benefits in the maintenance of organizations after the implementation of just-in-time (JIT) managerial philosophy. For this, a structured questionnaire was designed and sent to the 421 industries in India. Design/methodology/approach The designed questionnaire was divided into two sections A and B to assist data interpretation. The aim of the section A was to build general information of participants, type of organization, number of employees, annual turnover of the organization, etc. Section B was also a structured questionnaire developed based on a five-point Likert scale. The identified critical elements of the JIT were included in the questionnaire to identify the maintenance waste reduction benefits in the maintenance of organizations. Findings On the basis of the 133 responses, hypothesis testing was done with the help of Z-test, and it was found out that in maintenance, we can reduce a large inventory of spare parts and also shorten the excessive maintenance activities due to the implementation of JIT philosophy. All the four wastes: waste of processing; waste of rejects/rework/scrap in case of poor maintenance; waste of the transport of spares, and waste of motion, have approximately equal weightage in their reduction. Waste of waiting for spares got the last rank, which showed that there are little bit chances in the reduction of waiting for spares after the implementation of JIT philosophy in maintenance. Practical implications The implication of the research findings for maintenance of organizations is that if maintenance practitioners implement elements of JIT philosophy in maintenance then there will be a great reduction in the maintenance wastes. Originality/value This paper will be abundantly useful for the maintenance professionals, researchers and others concerned with maintenance to understand the significance of JIT philosophy implementation to get the expected reduction benefits in maintenance wastes of organizations which will be helpful in the great saving of maintenance cost and time side by side great increment in the availability of machines.

Reliability analysis of static liquefaction of loose sand using the random finite element method

2015 ◽  
Vol 32 (7) ◽  
pp. 2100-2119 ◽  
Author(s):  
Ali Johari ◽  
Jaber Rezvani Pour ◽  
Akbar Javadi
Keyword(s):  
Finite Element ◽  
Pressure Ratio ◽  
Monotonic Loading ◽  
Unit Weight ◽  
Soil Parameters ◽  
Loose Sand ◽  
Element Analysis ◽  
Content Type ◽  
Static Liquefaction ◽  
Random Finite Element

Purpose – Liquefaction of soils is defined as significant reduction in shear strength and stiffness due to increase in pore water pressure. This phenomenon can occur in static (monotonic) or dynamic loading patterns. However, in each pattern, the inherent variability of the soil parameters indicates that this problem is of a probabilistic nature rather than being deterministic. The purpose of this paper is to present a method, based on random finite element method, for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. Design/methodology/approach – The random finite element analysis is used for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. The soil behavior is modeled by an elasto-plastic effective stress constitutive model. Independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are selected as stochastic parameters which are modeled using a truncated normal probability density function (pdf). Findings – The probability of liquefaction is assessed by pdf of modified pore pressure ratio at each depth. For this purpose pore pressure ratio is modified for monotonic loading of soil. It is shown that the saturated unit weight is the most effective parameter, within the selected stochastic parameters, influencing the static soil liquefaction. Originality/value – This research focuses on the reliability analysis of static liquefaction potential of sandy soils. Three independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are considered as stochastic input parameters. A computer model, coded in MATLAB, is developed for the random finite element analysis. For modeling of the soil behavior, a specific elasto-plastic effective stress constitutive model (UBCSAND) was used.

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