A method of noncontact measurements of currents for control over corrosion protection of underground pipelines

We consider the basic principles and potentials of noncontact measurements of currents for control over corrosion protection of underground steel pipelines. The characteristics of the magnetic field and a solution of the inverse problem for a rectilinear current are analyzed. The necessary and sufficient conditions for the determination of current on measurements of the magnetic field above the route are formulated. We describe algorithms, an example of using a BIT-3 noncontact current meter, and full-scale tests for the insulation control and cathodic protection of a main gas pipeline. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 3, pp. 105–112, May–June, 1999.     

Computer for corrosion inspections of underground pipelines

The structure chart of a special computer for evaluating the technical characteristics of an underground pipeline is described and analyzed.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 54–56, January, 1995.     

Electromagnetic method and procedures of nondestructive inspection of the corrosion protection of underground pipelines

A triune mathematical model of an electromagnetic field is proposed, and procedures of fast noncontact inspection of underground pipelines are proposed. Methods and devices are developed for the determination of the distribution of cathodic protection current and the transition resistances of protective coatings in different sections of underground pipelines. The technology of integral, differential, and local inspections of main pipelines is described.     

Influence of geometrical instability on the results of noncontacting current measurements in underground pipelines

Methodological errors due to instability of the geometry in three modifications of measuring devices are investigated in application to noncontacting current measurements in underground pipelines.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 45–49, May, 1994.     

Determination of insulation defects by measuring currents in underground pipelines

The determination of the size of insulation defects in underground pipelines by measuring the attenuation factor of currents flowing in them is discussed. Analytical expressions for the size of defects are derived and results of calculations are presented. Translated from Izmeritel'naya Tekhnika, No. 6, pp. 47–49, June, 1999.     

Effect of the terrestrial magnetic field on direct-current measurements in underground pipelines

The effect of the secondary field of an underground pipeline, magnetized by the terrestrial magnetic field, on noncontacting measurement of direct current flowing in it is discussed. The systematic errors of three known measurement methods are compared. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 42–44, July, 1995.     

Determination of the parameters of piezoceramic elements from amplitude measurements

A new method of measuring the parameters of a piezoceramic element is proposed, the basis of which is the maximum values of the amplitudes of the conductance and its derivative. The method only requires simple automated instruments.     

Determination of structural parameters of metallic foams from permeametry measurements

An experimental technique, permeametry, is carried out in order to determine the dynamic specific surface area and the tortuosity of three nickel foams. A capillary-type model allows calculation of these structural parameters from pressure-drop measurements. Studying pressure drops of two different flow configurations also allows quantification of a third parameter due to the anisotropy of the material structure. The values of the parameters determined throughout this work are compared with those obtained in previous works using different experimental methods.Nomenclature A experimental coefficient defined by Equation 3 (Pa sm^–2) - A _vd dynamic specific surface area, related to volume of solid (m^–1) - A _ve specific surface area, related to volume of porous medium (m^–1) - B experimental coefficient defined by Equation 4 (Pas²m^–3) - Cr precision criterion - D hydraulic diameter of the cell (m) - d equivalent pore diameter (m) - f friction factor - H bed height or thickness of porous material (m) - J coefficient defined by Equation 8 (m^–1) - K coefficient defined by Equation 9 (m^–2) - l pore length (m) - mre mean relative error - n+1 number of pressure taps - P pressure drop (Pa) - R anisotropy factor or shape anisotropy ratio - Re superficial Reynolds number, Re = U _o d/u - Re_i interstitial Reynolds number, Re _i = U _o d/() - T tortuosity - U _o superficial velocity (m s^–1) - porosity - dynamic viscosity (Pa s) - fluid density (kg m^–3)     

Unsteady heat losses of underground pipelines

Analytic expressions are presented for the unsteady temperature distribution of the ground and heat losses of an underground pipeline for an arbitrary variation of the temperature of the medium being transferred and boundary conditions of the third kind at the pipe wall and the surface of the ground.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 2, pp. 339–345, August, 1977.     

Flow enhanced corrosion of water injection pipelines

A pipe spool from the subsea water injection piping network for oil operations at Eastern Desert was retrieved and internal corrosion and grooving were observed at the 6 O’clock position, in one section of the pipe, and not in the other. Two cuts from the sited piping were received for analysis to establish an overview of whether the failure is related to materials aspects or operating conditions. Results of visual inspection, chemical analysis, metallographic examination, SEM/EDX analysis, and mechanical testing showed that the corrosion resistance against flow for the quenched and tempered structure of the first cut was better than that of the cold rolled structure of the second cut. This is largely due to the uniform distributed polygonal ferrite and the small volume fraction of pearlite. Continuous removal of the loose adhered scales by electrochemical dissolution and mass transfer resulted in creation of fresh surfaces for further corrosive attack. This reduced the pipe wall below the critical thickness required to support the operating pressure and resulted in ductile failure of the pipe. Such mechanism of failure is known as the flow enhanced corrosion (FEC) mechanism. Failure in such mechanism is a catastrophic one that usually results in serious damage and injuries if not detected before undergoing.     

Transducers for contactless induction inspections of underground pipelines

The block diagrams of digital and analog transducers used for frequency normalization of the amplitude of the electromotive force that the field of a pipeline induces in an induction pickup are described. Mathematical expressions are given for designing such transducers.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 52–55, April, 1995.     

Calculation of the reliability of steel underground pipelines

We present basic principles of reliability calculations for steel underground pipelines resting on stochastic elastic foundation that based on the strength and stiffness criteria using the absolute maxima of arbitrary functions. Specific numerical examples illustrating a general calculation procedure are presented.     

Identification of coating defects in cathodically protected underground pipelines

Coating defects may occur, for many different reasons, at some points on the surface of a cathodically protected structure. These defects behave anodically and may cause strong localized corrosion. It is possible to identify the position of coating defects by using measured values of the electrochemical potential at some points in the electrolyte or on its surface. To achieve this, an inverse BEM‐based genetic algorithm is developed to identify the position of defects in cathodically protected underground pipelines. The formulation is validated through its application to practical problems involving strongly non‐linear polarization curves, infinite electrolytes, unknown number of defects and measurement noise. Copyright © 2003 John Wiley & Sons, Ltd.     

Microbiological corrosion of steel pipelines and mastic insulating coatings

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 4, pp. 97–101, July–August, 1988.     

Finite-element models for calculating the temperature fields of underground pipelines

A simple method of constructing finite elements for the numerical modeling of temperature fields, of underground pipelines is outlined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 2, pp. 321–323, August, 1985.     

Full-signature real-time corrosion detection of underground casingpipes

Corrosion monitoring and early detection of pits and wall thinning for casing pipes are considerably important to gas and petroleum industries since the frequently occurring corrosion at the internal or external parts of those steel casing pipes used in underground gas storage or oil fields causes production and environmental protection problems. In this paper, a new version of the direct current (dc) electromagnetic induction system is introduced in which a sensor system, based on the dc electromagnetic induction instrument, is coupled with an updated data acquisition system. Unlike the conventional dc induction instrument, the new system can achieve a full-signature logging response by providing all the measured flux leakage (FL) signals and eddy current (EC) signals to the computer logging system (CLS) on the surface. To transmit the information represented by large amounts of data acquired by downhole instruments to the CLS on the surface, a wavelet data compression technique has been incorporated. A VLSI integrated circuit (IC) which realizes the wavelet transform has been designed so that the real-time mode can be achieved during the logging operation. The circuit has been designed using CMOS n-well 2-μm technology and has been fabricated by MOSIS     

On the cathodic protection of thermally insulated pipelines

Thermal insulation and corrosion protection of heated pipelines used in moving oil/gas and heated products are accomplished industry-wide by using protective and insulating coatings supplemented by cathodic protection to protect any defected coating areas. A series of tests are carried out to study how the resistivity of the applied insulating layer polyurethane (PUR) can be affected by its specific gravity (as function of its porosity), as well as, the salt (NaCl) concentration in the surrounding electrolyte (water). The current densities required for cathodic protection of insulated steel pipe at the worst condition (i.e., lower resistivity of the insulating material) at ambient and elevated temperatures were determined. The results have showed: that a lower PUR foam density has lower percentage closed cells which lead to a decrease in the PUR foam resistivity. An increase in the salt concentration up to about 3.5% NaCl leads to about 40% increase in the current intensity required for CP of the insulated steel sheets. In this investigation zinc wire of diameter 5 mm was used as a sacrificial anode in two different manners parallel and spiral. The sacrificial anode was fixed adjacent directly to the electrical insulation under the PUR foam shows a complete protection of the pipes, i.e., about – 920 mV vs. Cu/CuSO₄, in the salty water with about 3.5% NaCl; this method guarantees optimum protection. The experiments performed at different temperatures up to 60 °C showed that increasing the temperature has a slight positive effect.