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2020 №04 (08) DOI of Article
10.37434/tdnk2020.04.01
2020 №04 (02)

Technical Diagnostics and Non-Destructive Testing 2020 #04
Technical Diagnostics and Non-Destructive Testing #4, 2020, pp. 3-7

Development of the method for assessment of serviceability and residual life of the main pipelines with service macrodelamination

O.T. Tsiryulnik, N.V. Kret, O.I. Zvirko, G.M. Nikiforchin
G.V. Karpenko Physico-Mechanical Institute of NASU. 5 Naukova Str., 79060, Lviv, Ukraine. E-mail: otsyrulnyk@gmail.com

Expert examination of defectiveness of rectangular elbows/bends of pipes in a compressor station of gas transportation systema fter 40 years of operation and of a linear above-ground section of the main gas pipeline-crossing over water obstacles in a mountain area after 30 years of operation was performed by nondestructive method of ultrasonic testing of pipe wall thickness with application of thickness meter with A/B scan MVX (DakotaUltrasonics). A set of diagnostic indications of hydrogen-induced macrodelaminations inside the pipe wall of a main pipeline was complemented by a new diagnostic electrochemical feature, namely polarization resistance. Its lowering by > 30 % allows prediction of such an enhancement of the stress-strain state on the pipe outer surface, which creates a risk of the macrodefect reaching the surface. A method was developed for evaluation of serviceability and residual life of pipes in a system of the main pipelines with service macrodelaminations, which allows for hydrogen role in the processes of development of such a type of macrodefects, service degradation of metal and application of nondestructive testing methods for controlling the level of metal damage inside the pipes. 10 Ref., 1 Table, 6 Fig.
Keywords: service degradation, steels of the main pipelines, diagnostic features of macrodelamination

Received: 09.07.2020

References

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