PSI - Issue 36

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

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In practice of surveying the state of underground metal pipelines (UP), mainly contact methods of measurements from the surface of the earth, which are relatively easy to use and essentially do not require sophisticated equipment , are used (Strizhevsky et al. (1981), DSTU 4219-2003, Karpash et al. (2007)). However, their essential disadvantages are: the complexity of providing reliable contacts with the UP and the soil, at transitions under rivers, in wetlands and in vegetation thickets on the route; the unreliability of contacts of the electrodes with the soil with high resistance to the surface of the earth (dry soils, asphalt, etc.); limited range of activities (local character of control); dependence of the signal on the ground resistance and depth of the pipe; the need to pre-specify the location of the pipeline (Nykyforchyn et al. (2009), Dzhala et al. (2018)). Intracellular defectoscopy makes it possible to detect defects in the metal wall of the pipe, but does not provide information on the state of insulation and corrosion protection of UP (Dzhala et al. (2018)). Therefore, the development and use of contactless methods and means of UP examinations are important (Sidorov and Kharionovskii (1993), Dikmarova et al. (2002), Nykyforchyn et al. (2009), Tsykh (2014), Dzhala et al. (2018)). The objective of the present research is to assess the possibility of testing the distribution of damages to insulation of UP by non-contact current measurements. 2. Contactless current measurements of underground pipelines Contactless methods of surveys on mobility, productivity and informativity have significant advantages over traditional contact methods (Strizhevsky and Kharionovskii (1981), DSTU 4219-2003, Karpash et al. (2007)). But they required special means of measurement and therefore were not widely used. The Karpenko Physico-Mechanical Institute of the NAS of Ukraine conducted a complex of researches of the electromagnetic field and UP signals, created algorithms, means of measuring and processing information about the state of insulation and corrosion protection of UP (Dzhala et al. (2018, 2019)). In order to increase the efficiency of information gathering along the UP routes, the method of contactless currents measurement (CCM) has been developed, the possibilities of its use for diagnostic examinations of UP have been investigated. Among the differential CCM are gradient (radial), invariant and parallax (azimuthal) (Dzhala et al. (2018)). With the created CCM equipment (Fig. 1) we quickly determine the location of UP, measure the distance to its axis (depth of occurrence) and the strength of the current flowing along the pipeline. The use of the developed method of CCM significantly increases the efficiency and informativeness of determining the transition resistance of UP and its components (Dzhala et al. (2019)).

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Fig. 1. Non-contact inspections of UP by CCM equipment by ( a ) parallax and ( b ) gradient methods.