PSI - Issue 36

Roman Dzhala et al. / Procedia Structural Integrity 36 (2022) 17–23 Roman Dzhala et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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We have the effect of current leakage during contactless measurements of the depth of UP near the damage to the insulating coating, which is manifested in the change of the sign of the error of measuring the depth h of UP over the damage (when moving along the route). It should be noted that the presence of the effect of current leakage during contactless measurements is experimentally confirmed in Tsykh (2014). Therefore, it can be used as the informative feature for the detection and selection of damage to the protective coating of UP. As it is shown by our calculations, the leakage effect (caused by errors in contactless measurements of UP current) is more vivid for the parallax method than for the gradient method, which is less sensitive to current leakage. According to the above given graphs, we analyse the possibilities of detection and differentiation (distinction) of local defects (through damage) of UP insulation by induction measurements of the characteristics of MF of currents. Fig. 5 shows the results of numerical simulation of the dependences of contactless measurements of the depth of UP and current J by the gradient method from distance Δz s between the places of two local damages. From the above mentioned results, it is evident that the method of CCM can distinguish individual local insulation damage located along the route at the distance greater than the depth of UP. 5. Conclusions CCM make it possible to monitor quickly the condition of the insulation in different sections of UP, to identify the location of insulation damage and their distribution along the route of UP. Additionally, CCM can be used to quantify the distribution of transition resistance of the insulating coatings of UP and its components along the pipelines. Leakage of current due to the insulation defect of UP creates an anomaly of the spatial distribution of magnetic field, which causes the characteristic specific errors of contactless measurements of the depth and current of UP. Contactless depth and current measurements can be used as an informative feature to detect and select damage to the protective cover of UP. By the method of CCM it is possible to distinguish local damages of isolation located at the distance along UP not less than depth of occurrence of UP. References David Norman, 2007. Pipeline Coatings, External Corrosion and Direct Assessment. CORROSION 2007, Nashville, Tennessee. http://www.davidnormancorrosioncontrol.com. Dikmarova, L.P., Kornienko, V.Yu., 2002. Determination of dimensions of through-thickness damages in underground pipeline insulation. Information Extraction and Processing 16(92), 9 – 12. [In Ukrainian] DSTU 4219-2003. Steel main pipelines. General requirements for corrosion protection. Derzhstandart of Ukraine, Kyiv. 74. [In Ukrainian] Dzhala, R.M., Dzhala, V.R., Verbenets’, B.Ya., Semenyuk, O M., 2012. Differentiation of local damages of current line insulation acco rding to magnetic field distribution. Metody ta prylady kontrolu yakosti 1(28), 33-40. [In Ukrainian] Dzhala, R.M., Dzhala, V.R., Ivasiv, I.B., Rybachuk, V.G., Uchanin, V.M., 2018. Electrophysical methods for nondestructive testing of defects in structural elements. in “Technical diagnostics of materials and structures: Reference manual”, Vol. 4. Nazarchuk, Z.T. (Ed.). Prostir-M, Lviv, 356. [In Ukrainian] Dzhala, R., Dzhala, V., Savula, R., Senyuk, O., Verbenets’ , B., 2019. Determination of components of transient resistance of underground pipeline. Procedia Structural Integrity 16, 218-222. Dzhala, R. М. , Yuzevych, L. V., 2019. Modeling of relationships between the mechanoelectrochemical parameters of the metal surface. Materials Science 54(5), 753 – 759. Karpash, O.M., Vozniak, M.P., Vasyliuk, V.M., 2007. Technical diagnostics of oil and gas supply systems. Fakel, Ivano-Frankivsk, 341 p. [In Ukranian] Nykyforchyn, H.M., Polyakov, S.G., Chervatyuk, V.A., Orynyak, I.V., Slobodyan, Z.V., Dzhala, R.M., 2009. Strength and durability of oil and gas pipelines and storage tanks, In: Panasyuk, V.V. (Ed.). “Fracture mechanics and strength of materials: Reference book”, Vo l. 4. Spolom, Lviv, 504 p. [In Ukrainian] Nyrkova, L.І. , Osadchuk, S.О. , Klymenko, А.V. , Rybakov, А.О. , Mel’nychuk , S.L., Prokopchuk, S.М. , 2020. Influence of the corrosiveness of a medium on the ratio of the cathodic protection current to the ultimate diffusion current for KH70 pipe steel. Materials Science 56(3), 417-424. Sidorov, B.V., Kharionovskii, V.V., 1993. Application of the C-SCAN system at inspection of a condition of an insulating covering. Gasindustry 6, 18-20. [In Russian] Strizhevsky, I.V., Zinevich, A.M., Nikolsky K.K., Glazkov, V.I., Kotik, V.G., 1981. Protection of metal structures from underground corrosion: Handbook. Nedra, Moskva. 294 p. [In Russian] Tsykh, V.S., 2014. Development of method and instrument for buried pipelines coating damages monitoring. NTUOG. Ivano-Frankivsk, 20 p. [In Ukrainian]