(ASSESSMENT OF RELIABILITY AND PROSPECTS FOR THE USE OF THE IN-LINE INSPECTION RESULTS AT ELASTOPLASTIC BENDING SECTIONS OF MAIN GAS PIPELINES)
New capabilities of in-line inspection of main gas pipelines allow identifying not only anomalies of the pipe body and welded joints, but also areas with non-standard bend radii, for which hazard assessment is performed. At the same time, some methodological provisions of the gas transmission system technical condition and integrity management system are distinguished by a certain additional conservatism in assessing the danger of anomalies of the pipe body and circumferential welded joints. The reason is the need to take into account the error of in-line inspection tools, possible concurrent cracks in the anomaly zone, mechanical properties of the pipe steel, and etc. In the end, this leads to an overestimation of the anomaly (excessive danger is considered).
The article presents the results of many years’ practice of using in-line inspection data when assessing the condition of main gas pipeline sections with non-standard bend radii and determines the degree of reliability of these data. To reduce the observed conservatism in assessing the danger of anomalies, the authors suggest applying the plane-sections hypothesis. According to it, the beam bending leads to the forming of compression and tension areas. Taking into account different combination of possible operational loads and impacts on the main gas pipeline, the plane-sections hypothesis, at the current status of inspection tools development, is expedient to apply as a part of expert-based methods.
R.V. Zakiryanov, Gazprom transgaz Ufa LLC (Ufa, Russia), email@example.com
A.V. Yarovoy, Gazprom transgaz Ufa LLC, firstname.lastname@example.org
I.M. Islamov, PhD in Engineering, Gazprom transgaz Ufa LLC, email@example.com
M.V. Zakiryanov, PhD in Engineering, Gazprom transgaz Ufa LLC, firstname.lastname@example.org
M.A. Shashkov, Separate Business Unit, LLC NPC VTD (Beryozovsky, Russia), email@example.com
A.N. Kukushkin, Separate Business Unit, LLC NPC VTD, firstname.lastname@example.org
S.A. Stenin, Separate Business Unit, LLC NPC VTD, email@example.com
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