Underground Metallic Pipelines Research Articles

Research on magnetic gradient method in underground metal pipeline detection

When the underground metal pipeline is powered by direct current, the magnetic field will be generated around it, and the buried information of the pipeline can be deduced by the change of the magnetic field. Therefore, a method of detecting underground metal pipeline by magnetic gradient is introduced. The mathematical relationship between the magnetic gradient and the buried depth of underground pipeline is derived. The theoretical feasibility of this method is verified by forward simulation, then the physical experiment proves that this method has high detection accuracy.

Determining the Place of Depressurization of Underground Pipelines (Gas Pipelines): New Solutions in Industry based on Thermal Image Analysis Using Computer Vision

An analysis of the analytical ratios of the mathematical model, which characterizes the development processes of a corrosion cavern on the surface of an underground metal pipeline, which is placed in the environment of moist soil with an electrolyte solution, is performed. A neural network method for estimating the main informative parameters for determining the place of gas depressurization on the surface of an underground pipe and an expression for calculating the change in gas pressure around a crack after its formation have been developed. The principles of determining the limit values of the parameters of the “pipe-cathodic protection” system are formulated, considering the metal's quality and strength criteria at the top of the cavern. Depressurization causes fluid to flow from the pipeline to the surface. Thermal imaging devices make it possible to detect the place of damage to the pipeline based on the temperature properties of the surrounding objects. Thermal imaging can be used to analyze the location of a fluid leak or warn of it using computer vision. Thus, preventing an accident or even a catastrophe in the pipeline. In the work, the colour gamuts of the thermal image in the places of depressurization are considered, and the regularities of detecting damaged sections of the pipeline are established.

Underground Metal Pipeline Localization Using Low-Cost Wireless Magnetic Sensors Mounted on an Excavator

To minimize the excavation damage of underground pipelines, in this article, we propose to provide real-time feedback to operators by monitoring the distance information from the underground pipeline. Despite multiple efforts to locate underground ferromagnetic pipelines using the magnetic anomaly detection, it has not been implemented in real-time excavation operations due to low signal-to-noise ratios, unknown external magnetic interference (EMI), and high computational power. To address these limitations, we propose an approach to locating a custom-designed wireless sensor system on the excavator bucket to increase accuracy of real-time distance estimation with efficient EMI cancelation. We present the system using a 14:1 lab-scaled excavator and six sizes of ferromagnetic pipes. To create a distance estimation model of each pipe, we measure the magnetic anomaly caused by ferromagnetic pipes from eight distances (from 5 to 75 mm, spaced 10 mm apart). The wireless system with the localization algorithm successfully estimates the distance between the sensor and the pipe with a less than 4.38 ± 1.62 mm error overall. This pilot study shows that the proposed system with the localization algorithm is able to accurately locate pipes. This will lay the foundation for providing accurate spatial information, and ultimately prevent critical excavation/drilling damage at construction sites.

Economic analysis of DC power sources used in impressed current cathodic protection of underground pipelines

Objective: The objective of this study is to calculate and analyze the economic parameters of three main DC power sources i.e. Thermoelectric Generator, Transformer Rectifier, and solar photovoltaic (PV) Solar System, which are widely used in impressed current cathodic protection (ICCP) of underground pipelines. Methodology/Analysis : Initial or capital cost, operation and maintenance costs of the afore-mentioned DC sources are computed, for a practical ICCP system of high transmission underground pipeline over a period. Present worth analysis technique of economic analysis with inflation adjustment using a spreadsheet is adopted to compute these values. The analysis period of 20 years is used for present worth calculations of these DC sources. Findings: The cost efficiency of DC power sources for an ICCP system have been discussed in very few research papers. The calculations are made for either only one DC source at a time or the comparison is based on calculation without inflation adjustment. This study, in line with the currently adopted methodologies, provides a far easier and more comprehensive comparison and analysis of the most economical DC source for the ICCP system of underground metallic pipelines. Novelty/ Improvement: DC power sources play a pivotal role in an ICCP system that helps to mitigate the rate of corrosion in underground pipelines. This study contributes towards choosing the costeffective DC Power source for an ICCP system of underground pipelines. The results are drawn using practical data. This subsequently helps in mitigating the rate of corrosion in these pipelines. Keywords: Economic analysis; corrosion; DC power source; impressed current cathodic protection; underground pipelines

Technology of detecting deep underground metal pipeline by magnetic gradient method

The application of trenchless technology, such as pipe pulling, pipe jacking, directional drilling and so on, makes the deep buried underground pipeline more and more in the project, and most of the geophysical exploration technology has poor detection effect, which makes it become the difficulty in the underground pipeline detection. This paper mainly expounds and analyzes the principle and construction method of magnetic gradient method for detecting deep underground pipelines, and introduces the application of magnetic gradient method in the detection of deep underground pipelines with two natural gas pipelines in Shijiazhuang road project.

Classification and analysis of instruments for measuring corrosion damage to internal surfaces of underground metal pipeline

This paper presents a classification of corrosion damage to the inner surface of the pipeline, a comparative description of the effect of corrosion damage on the inner surface of metal pipes. The most common on the inner surfaces of a metal pipeline are ulcerative, pitting, intergranular, cracking, pitting, crevice and through corrosion. Methods and tools for controlling corrosion damage are presented, and their capabilities are analyzed. It is shown that the development of diagnostics of the inner surface of pipelines is on the path to creating robotic tools. Existing robotic devices today have disadvantages. Firstly, for some injuries, the presence of an operator at the place of passage of the pipeline is necessary, which does not exclude subjective diagnostics. Secondly, as a rule, methods require emergency excavations. Thirdly, they are narrowly targeted, they do not allow to diagnose all types of corrosion damage in general. In conclusion, a modular robotic complex is proposed, which combines a number of functions that exclude these shortcomings.

Hydrochemical Characteristics, Groundwater Quality and Sources of Solute in the Ramganga Aquifer, Central Ganga Plain, Bareilly District, Uttar Pradesh

The quality of groundwater is determined in parts of Ramganga basin, Bareilly, UP, India. Spatial variation of all the major ions shows south-eastern increasing trend except chloride and sulphate. Groundwater in the area belongs to the Mg2+-Ca2+-HCO3− cation facies. The monsoonal rainfall changes the ionic abundance order from HCO3−>Cl−>NO3−>SO4−2> F− and Mg2+> Ca2+> K+>Na+ of pre-monsoon to HCO3−>Cl−> SO4−2>NO3−>F− and Na+> Mg2+> Ca2+> K+ of post-monsoon. Solute acquisition processes indicated that the rock weathering is the major mechanism of ions sources in groundwater. A coupled carbonate and silicate weathering type along with ion exchange processes are responsible for particular groundwater chemistry. Groundwater quality parameters were tested for drinking, irrigation and corrosion purposes. It is found that 8.5%, 26%, 49%, 14% and 3% of the samples fall under the excellent, good, poor, very poor and unsuitable category respectively. SAR, Na%, RSC and Kelly index suggests that groundwater is safe for irrigation purposes. But high TDS of few samples suggested the salinity hazard while using it for irrigation purposes. Low CR values indicated a lower degree of corrosion hazard to the underground metal pipelines in the area.

Qualimetric Analysis of Pipelines with Corrosion Surfaces in the Monitoring System of Oil and Gas Enterprises

The introduction of new technologies for diagnosing underground metal pipelines with dangerous surface defects is a practically important task. That is why studies aimed at improving the methods of assessing the quality of deformed metal pipelines and structural elements are necessary and relevant. The evaluation of the effectiveness of engineering and technological solutions for oil and gas enterprises needs improvement. In this context, an important task is to solve the problem of quality control (including durability) of gas and oil transportation systems and the improvement of appropriate metrological support. Based on surface physics and fracture mechanics, development of a methodological approach to assessing the quality and resource of underground metal pipelines (UMP) of oil and gas enterprises, taking into account the constructions strength, corrosion fatigue, parameters of corrosion protection and metrological support. Results of processing of normative documents and scientific works in the field of gas transportation enterprises, as well as methods of surface physics, mechanics of deformed solid body, fracture mechanics, qualimetry regarding the system “pipeline (UMP) – coating”. A new criterion for the strength of the surface of a metal underground pipe is proposed, which characterizes the peculiarities of bond fractures (adhesion) between the coating and the metal. Using the criterion of the strength of a metal tube with a defect in the electrolyte, the dependence of the critical internal pressure of the gas pipeline (UMP) on the geometric and energy (elastic and plastic) parameters of the metal, as well as the current of the anodic dissolution, which characterizes the features of the crack propagation at the bottom of the corrosion cavern. On the basis of surface physics and fracture mechanics obtained, a methodology for evaluating the quality of underground metal pipelines of oil and gas enterprises was developed to determine their resource, taking into account strength, corrosion fatigue, parameters of corrosion protection and metrological support.

Diagnostics of Temperature Regime of Technological Environments of Underground Pipelines in the Monitoring System of Oil and Gas Enterprises for Providing of Safe Exploitation

The diagnosed density of corrosion was diagnosed on the outer surface of the underground metal pipeline, depending on the distance L to the compressor station, taking into account the influence of soil, defects, thermal impulses, mechanical vibrational vibrations and corrosion fatigue. The basic relations of the mathematical model for the description of thermal processes and mechanical vibrational vibrations that lead to low-cycle corrosion fatigue in the pipe are proposed. It is noted that the measurement of corrosion currents and polarization potentials at the boundary of the metal pipeline–soil can be detected by devices of types BVS (noncontact current meter), VPP-M (polarization potential meter) and equipment for for diagnostic inspections and monitoring of corrosion protection of underground pipelines (UGPL). Consider for compare the distribution of corrosion current densities and accidents for the pipeline at a distance of L=0..30 km from the compressor station. It is found that the correlation coefficient between them KLD=0,76 is not enough to establish causation. A difference is formed in which the corresponding corrosion current density distribution for a non-oscillating temperature background is subtracted from the total corrosion current density distribution in the range L=0…30 km. In this case, the part of the distribution that is related to the frequency of thermal pulses is highlighted.The correlation coefficient of KWD0.92 is established between the part of the distribution that is related to the frequency of thermal pulses and the distribution of accidents for the pipeline at a distance of L=0…30 km from the compressor station. Based on KWD, it can be argued that the causal relationship between the distribution of heat pulses and accidents is quite plausible. The noted information is important for improving the methods of operation of compressor stations of oil and gas enterprises, taking into account changes in the frequency of heat pulses with regard to improving the quality of by-laws on labor protection regarding gas supply systems.

Determination of the Place Depressurization of Underground Pipelines in the Monitoring of Oil and Gas Enterprises

Analytical correlations of mathematical model that characterizes the processes of development of corrosive cavity on the surface of underground metallic pipeline are analysed. A pipeline in the environment of moist soil with solution of electrolyte is placed.In the top of cavity a crack appears and translates the system “underground pipeline (UP) – pumping station (PS)” in the state of depressurization.A new approach is proposed for diagnosing places of underground pipeline depressurization on the basis of two types of devices: pressure sensors and non-destructive testing devices, with the help of which we measure potentials and corrosion currents in surface defects.The presence of only pressure sensors makes it possible to set the coordinates of depressurization with a large error – 20…25%. Diagnosis of the pipeline only by devices BVS-K, VPP-M (at the first stage) allows to reveal surface defects. But this information is not enough for a qualitative experiment, as shown by the qualimetric quality criterion. Taking into account the pressure data in the second stage allows to determine which of the defects is the leakage point.A test example for the distance L1 = 6 km from the pumping station of the pipeline is considered. The results of the experiment are used for the example and the growth time of the corrosion crack t = 0.62 year is established.On the basis of computational experiment the errors of estimating of crack growth time t and coordinates of the leakage points was established. They present 5…7 %. Based on the method of neural networks, the main informative parameters for determining the places of depressurization on the surface of the underground pipe are estimated. A method for estimating the gas pressure change in the vicinity of the crack after depressurization of the pipeline was proposed. The principles of determining the limit values of the parameters of the system “pipeline – pumping station” taking into account the criteria of quality and strength of the metal are formulated.

Research on Characteristics of Grounding Electrode of HVDC Transmission

The grounding electrode is an important part of HVDC transmission system, especially in monopole operation. Based on the actual operation of the grounding electrode of Guanyin Pavilion in the ±500kV Goose-commutation station in Huizhou, Guangdong, this paper analyses in detail the specific influencing factors of the grounding electrode on the surrounding environment, underground metal pipelines and AC grid. Daily maintenance work considering current distribution, temperature, humidity and step voltage is also proposed to strengthen the understanding and attention of operation and maintenance personnel to the grounding electrode.

Improving the diagnostics of underground pipelines at oil­and­gas enterprises based on determining hydrogen exponent (PH) of the soil media applying neural networks

A set of key parameters and information flows has been formed to simulate stages of probing the outside surface of underground metal pipelines (UMP) taking into account pH of the soil contacting with the pipe metal. Specimens of 17G1S steel placed in acid, alkaline and neutral media were examined using a polarization potential meter in a complex with a contactless current meter. Principles of application of neural networks (NN) in processing experimental results were formulated. A database has been developed. It meets the initial conditions for controlling the soil pH at the boundary with the metal under real conditions. Elements of the optimization approach for assessing pH of a coated UMP in the soil medium were proposed. The approach is based on the multiplicative qualimetric criterion of quality for the UMP section taking into account two groups of coefficients. The first group of coefficients refers to the internal coefficients and characterizes the metal pipeline and the second group refers to the external medium (i.e., soil electrolyte). Elements of the optimization approach for assessing pH of the coated pipeline in the soil medium were proposed. An NN was presented for the pipeline-coating system, which: 1) is capable of solving the problem of cluster analysis and image classification; 2) makes it possible to process data without their prior spectral transformation operating with discrete counts of information signals. The proposed NN type allows it to dynamically expand its own knowledge base of possible types of defects in controlled objects (pipelines) in the process of operation. With the help of the NN, soil pH was assessed for an UMP of 17G1S steel for three situations. The above information is important for improving the methods for controlling oil-and-gas enterprise UMPs, in particular, the methods for a correct assessment of anode current density in metal defects taking into account nonlinear character of informative parameters.

Forming the toolset for development of a system to control quality of operation of underground pipelines by oil and gas enterprises with the use of neural networks

A set of defining parameters for modeling stages of a surface defect propagation in the outer surface of a metal pipeline taking into consideration fatigue strength has been formed. For a section of a pipeline with a surface defect, it was proposed to use an algorithm of forecasting polarization potentials using means of neural networks. A procedure of functioning of the testing set was elaborated for estimating efficiency of neural networks. The procedure includes appropriate training methods. According to the results of analysis of interconnected deformation and corrosion processes, elements of a methodology of formation of information support for forecasting service life of a linear part of underground metal pipelines taking into consideration corrosion fatigue have been developed. Known results of estimation of service life of underground metal pipelines assumed linear nature of corrosion rate. Relevant information was presented in international and national standards. Recent experimental studies have shown that it is advisable to take into consideration nonlinear nature of corrosion rate in the outer surface of underground metal pipelines (BMP). A BMP section was inspected with the aid of a polarization potential meter together with a contactless current meter and principles of using neural networks for processing experimental results were formulated. An example of actual BMP was considered and analyzed for metal of a pipe of 17G1S grade steel with a corrosion defect in its outer surface. This analysis has resulted in estimation of metal service life and revealed nonlinearity characterized by magnitude of d=1.136. A control method and procedures for estimating polarization potentials with the help of neural networks were proposed. They make it possible to describe the process of corrosion defect propagation into the depth of the pipe wall physically sound and mathematically more correct in contrast to the standard procedures. The information presented is important for improving methods of control of underground metal pipelines operated by oil and gas enterprises, in particular, methods of correct measurement and evaluation of polarization potentials and anode currents in insulation defects taking into consideration nonlinearity of informative parameters

Induced electromagnetic field on underground metal pipelines running parallel to nearby high voltage AC power lines

High voltage AC (HVAC) power lines can induce significant amount of voltages on underground gas/oil metal pipelines in areas where they share similar Right of Way (RoW), the situation becoming serious particularly in case of fault conditions. Electromagnetic field generated by the HVAC power lines on these pipelines, generate unwanted voltages which present threats to the pipeline and its associated protective equipment such as cathodic systems. The aim of this research is to compute induced voltage on pipeline running parallel to HVAC power lines. The study was conducted using CDEGS software package and revealed that under steady state condition, results were in agreement with GB 6830-1986 standard. However, high currents are generated under single phase to ground short circuit rising the potential of adjacent soil including the underground pipeline beyond limits. Therefore, the gradient control wire mitigation technique is proposed to reduce these voltages to safe limits.

Efficiency and Cost Analysis of Power Sources in Impressed Current Cathodic Protection System for Corrosion Prevention in Buried Pipelines of Balochistan, Pakistan

Corrosion is the physical deterioration of metals, including buried metal structures and gas pipelines, resulting from chemical reactions between metals and the surrounding environment. Cathodic protection of these underground metal structures & pipelines can be achieved either by the Impressed Current method or by the sacrificial anodes method. This research paper focuses on the corrosion prevention of buried metal structures in general and gas pipelines in particular, by the novel method of Impressed Current Cathodic Protection (ICCP) which uses electrical current from an external DC power source for its operation. Three major DC power sources i.e. Transformer Rectifier, Thermoelectric Generator and the Solar System are selected for this purpose and are projected over a period of time in a pre-designed ICCP for high transmission underground gas pipeline in Balochistan province of Pakistan. The efficiencies of these three power sources are then analysed and compared according to the climate effects, the versatility effects, the intensity of power output, their operational limitations and their initial, running and maintenance costs. The measured results will aid the selection of efficient and robust DC power source for ICCP design and will contribute to mitigating and controlling the corrosion rate in underground pipelines. Based on analysis of the measured results for the three available DC sources, the Solar System was found as the most efficient DC power source for Impressed Current Cathodic Protection of buried gas pipelines. The selection of efficient corrosion protection system will result in a smooth flow of oil and gas products through these buried pipelines which may otherwise lead to huge monetary and accidental losses when get corroded.

DIELECTRIC COATINGS AND THEIR EFFECT ON CORROSION PROTECTION OF THE OUTER SURFACE OF UNDERGROUND PIPELINES

This paper presents comparative analysis of influence of main factors, determining characteristics of dielectric coatings, both on the corrosion of underground metal pipelines and on their cathodic protection. At the same time, it was identified that, as a priority approach in the development of coatings to protect pipelines in the ground (without the use of cathodic protection), it is necessary to choose to reduce the electrical conductivity of the coatings as a result of their saturation with soil electrolyte. This measure significantly reduces the efficiency of corrosion elements that are likely to occur when dielectric coating is damaged. As for priority in the development of coatings for combined protection of pipelines in the ground, it is necessary to increase the mechanical strength of coatings and to implement a set of measures to prevent the formation of insulation defects and to eliminate them. Actions taken in this direction significantly reduce the amount of protective current necessary for active corrosion protection of underground metal structures.

DEVELOPMENT OF INFORMATION SUPPORT OF QUALITY MANAGEMENT OF UNDERGROUND PIPELINES

Recommendations are worked out in relation to the evaluation of longevity and quality of underground metallic pipelines in the conditions of corrosion fatigue. The features of early exposure of crisis (before accident) situations are set. A complex qualimetric criterion is offered for determination of level of quality of pipeline by the account of his technological specific. The elements of investment project and methodology of estimation of resource are worked out. and also influences of factors of different nature on risks and possibility of accident of gas pipelines. The model of corrosion fatigue of metal is based on power criterion of destruction mechanics according to which there is an act of destruction in an arbitrary elemental volume of a material if the total irreversibly scattered energy of plastic deformation for all load cycles will reach a critical value equal to the energy of destruction. In order to control the corrosion process taking the polarization potential into account, a criterion relation is used to determine the rate of residual corrosion of a metal in the defect of the insulation coating, in particular, at the top of the crack, which is an anode region. The adhesive strength criteria of biocorrosive aggressive soil, mechanical criteria for the stress intensity factor, the criterion of corrosion resistance defect, criterion correlation for estimating the speed of residual corrosion in defect of insulation coating with imposed diagnostic weight characteristics and diagnostic value of tests, that complement, clarify and improve the corrosion monitoring system of pipelines, helpful for controlling and optimizing of the corrosion process, and Development of recommendations for anti-corrosion protection of metal are used in areas with non-stationary plastic deformation.

Bituminos Insulations Durability of Underground Metallic Pipelines II. Laboratory study on the aging of bituminous material

The structural and physicochemical changes that lead to the aging of the bituminous insulation of underground metallic pipelines were determined through various investigations (XRD, dielectric spectroscopy and thermal analysis � coupled techniques TG + DTA + DTG). The resistance to moulds of the bituminous insulation was evaluated by using specific microbiological methods and the dominant microbiological species found in the soil where the investigated bituminous material was exposed for 19 years were identified. The measurements carried out on samples taken from site showed that the bituminous material used in the anti-corrosive isolation of steel pipes has a very low resistance to microorganisms; thus, the dielectric qualities of bitumen deteriorate substantially (tg� increases 3-4 times). The exposure of the bituminous insulation to different climatic conditions and to solar radiation (UV-IR) leads to a decrease in the dielectric losses in the insulation and to an increase in crystallinity and thermo oxidative reactivity of bitumen, thus leading to a significant decrease in the material�s resistance to the action of fungi.

Bituminous Insulations Durability of Underground Metallic Pipelines I Field investigations

The corrosion state of an underground metallic pipeline of �161 mm and 565 m length was assessed by specific electrical and electrochemical measurements. The investigated pipe, buried in 1997, was protected against corrosion by successive layers of bituminous material with a total thickness of 1 to 1.2 mm. The pipeline crosses three electrified railway lines (50 Hz - 28 kV), and then its route is approximately parallel to these lines; thus, the induced AC voltages between line and ground were calculated obtaining values between 4.05 and 7.1 Vrms, in good agreement with the values measured in the accessible points. The measurements regarding the insulation capacity against corrosion of the bituminous insulation, performed at one month and after 19 years of burial, showed an increase of the average cathode current density needed for obtaining the protection potential in the range �1.00 � �1.28 VCu/CuSO4 of approx. three times (from 6.65 up to 19.96 mA/m2), in good agreement with the evolution of the insulation resistance measured between the steel pipe (having a contact area with the ground of 270.5 m2) and a ground socket of 4 W, which decreased from 995 to 315 kW. Following the analysis and processing of the field collected data, it is considered that, by implementing a cheap cathodic protection system (without cathodic current power supply), based on the rectification of the AC induced voltage, the safe operation period of the investigated pipeline may be extended by at least 50 years.

Design and Field Implementation of Auto Tuned Virtual Instrumentation Corrosion Controller

Corrosion in underground metallic pipeline leads to leakage which is hazardous when oil/natural gas is transported. Rate of corrosion in metal pipeline can be controlled by impressing dc current to the gas pipeline and thereby making metal pipeline to act as cathode of corrosion cell. Proportional integral controllers are used in impressed current cathodic protection application; tuning of proportional and integral constants of these controllers requires expertise. Step open, step close and relay tuning methods are compared; relay tuning provided better results for cathodic protection application. Ziegler–Nichols tuning formulas are used to select tuning parameters based on loop response. Virtual instrumentation is used for design, development, testing and field implementation of auto tuned PI controller. Proposed auto tuned proportional integral impressed current cathodic protection controller precisely controls corrosion in pipeline by selecting optimum proportional and integral constants. Controller effectiveness is cross verified using electrical resistance probe.