English

Vol. 7 3, 2017 p 32-40

Pages

Article name, authors, abstract and keyword

32-40

Justified choice of repeated test interval as a guarantee of faultless pipeline operation

Yury V. Lisin a, Dmitriy A. Neganov a, Viktor M. Varshitsky a

a Pipeline Transport Institute, LLC (Transneft R&D, LLC), 47a, Sevastopolskiy prospect, Moscow, 117186, Russian Federation

https://doi.org/10.28999/2541-9595-2017-7-3-32-40

Abstract:
Introduction. The paper shows the analysis of modern approaches to performance of repeated hydraulic tests to ensure the integrity of operated pipelines with growing fissure-like defects and corrosion induced defects. Advantages and disadvantages of different approaches are listed. A possible damaging effect of hydraulic testing is mentioned to be related to a probable crack initiation of pre-critical defects. The number of such cases is insignificant, as only defects within a limited range may be crack-initiated without degradation at the preset pressure. If the defect size exceeds the range, the defect shall be detected; if its size does not meet the range, the defect shall be damped.
The use of repeated hydraulic tests is the most effective at the pipeline sections where in-line inspection is impossible: e.g. for jump-over lines and process pipelines. The article describes a defect detection scheme depending on how close applied stresses are to the defect ultimate stress.
Materials and methods. An analysis of methodical approaches for calculation of repeated tests for a section with growing fissure lime defects and a section with corrosion related growing defects is performed. The analysis of the results of a calculated assessment of an interval of repeated hydraulic tests of the pipeline section with fissure-like and corrosive developing defects is given. There was researched a dependence of the interval of repeated tests on the ratio of test pressure and operating pressure, the ratio of operating pressure and bearing capacity of pipes, on the characteristics of the impact strength of the pipe metal and welded joints, on the parameters of the pipe metal cyclic crack resistance, on the actual cycle of operating pressure and corrosion rate.
Results and conclusions. The article shows that choosing pressure of hydraulic tests depending on the actual cycle of operating pressure, corrosion rate, characteristics of the pipe metal impact strength and cyclic crack resistance, and the value of operating pressure provides a required interval of repeated tests.

Keywords: hydraulic tests, operating pressure, bearing capacity, cycling crack resistance

Reference for citing:
Lisin Y. V., Neganov D. A., Varshitsky V. M. Justified choice of repeated testing interval as a guarantee of faultless pipeline operation. Naukatekhnol. truboprov. transp. neftiinefteprod. = Science & Technologies: Oil and Oil Products Pipeline Transportation. 2017;7(3):3240.

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