Comprehensive assessment of the technical condition of gas pipelines 1420 mm at sites between 5 compressor stations to determine the need for modernization of equipment and reconstruction of the most loaded areas is made.

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    The assessment included:

• preliminary assessment of the technical condition with the analysis of design and operational documentation with the reproduction of the situational plan along the pipelines' route;

• research of the mechanical characteristics of the material of the pipes after a long 30 years of operation and their comparison with the archival material for determining the degree of degradation with time characteristics of strength, crack resistance and impact strength, determination of resistance to stress corrosion cracking, the implementation of metallographic studies to determine the change in the structure of the pipe material;

• development of a universal procedure for designing the system of electrochemical protection and determination of the effectiveness of the systems of corrosion protection of any complexity. The procedure includes: the construction of a computer model of electrochemical protection for the assessment of the protective potential, the determination of isolation disturbance, the calculation of the resistance of the anode ground, etc .; assessment of the quality of passive and active electrochemical protection with the analysis of seasonal results of measurements of control indicators; assessment of compliance of cathodic protection stations maintenance with technological regulations and criteria;

• construction of a computer model of multi-line pipelines with jumpers and calculation of operational pressures and temperature distribution along the pipeline route for different regimes of transportation, taking into account the pneumodynamic resistance, product losses, product flow between two threads of main gas pipelines, etc.;

• determination of the stressed state of the pipelines at loading by internal pressure and taking into account deformation in the curvilinear trench according to the 3D coordinates of the spatial position of the axial line;

• analysis of defect statistics with the definition of probabilistic distributions of their sizes, likelihood of detection depending on size, speed of growth, etc.;

• assessment of the danger of defects detected during the inline diagnostic and their ranking on the degree of danger, the determination of permissible pressures, and the response time (repairs);

• determination of potentially dangerous areas of possible detection of stress-corrosive defects by features accompanying stress-corrosion on the basis of the original computer procedure of segmentation of pipelines by calculated and discrete empirical parameters.