Assessment of the technical condition crossing «Shebelynka–Dykanka–Kyiv» main gas pipeline across the railway track

Abstract

Purpose. To comprehensively assess the technical condition of the Shebelynka–Dykanka–Kyiv main gas pipeline crossing, 1220 mm in diameter, over a single-track railway and determine its continued safe operation in accordance with current regulations. The methods. The technical condition of the main gas pipeline crossing was assessed in accordance with current regulations using a local inspection method with pitting. During the pitting, visual, dimensional, and instrumental inspections of the insulation, the outer surface of the pipes, and welded joints were performed, including wall thickness measurements, ultrasonic and radiographic inspection of defects, as well as checking the burial depth and protective structures, with subsequent comparison of the results with the design. Findings. The crossing is operational, with no signs of critical damage. The strength of the pipes and welded joints meets regulatory requirements, with a minimum wall thickness of 14.4 mm. No internal defects were detected in the base metal. Certain nonconformities were identified: localized insulation degradation, insufficient burial depth, pipe-to-casing contact, and reduced casing length. In Test Pit No. 2, unacceptable defects in the circumferential welded joint were detected, which were compensated for by installing a reinforcing steel coupling. The possibility of continued operation without reducing the operating pressure during scheduled maintenance was substantiated. The originality. The dependences of measured values of the polarization potential of the pipe-to-ground system were experimentally established based on detailed in-situ measurements in test pits. The results made it possible to evaluate the influence of test pitting on changes in the pipeline's electrochemical state and confirm the stability of the protection system's effectiveness under conditions of local soil disturbance. Practical implementation. The results can be used to predict the degradation and remaining service life of gas pipelines and implement a risk-based approach to maintenance, thereby improving the safety, reliability, and cost-effectiveness of similar facilities.