Severstal completes testing of a new generation of large-diameter pipes

by David Fleschen

Severstal has successfully completed full-scale field pneumatic tests of a new generation of large-diameter pipes (LDP) of strength class X80 with high deformation capacity, confirming their readiness for use in the construction of main gas pipelines.

The new generation of pipe products was developed as part of Severstal and Gazprom’s 2019-2022 Scientific and Technical Cooperation Program. The final stage of research and testing was organized by Severstal. The tests, which took place at a special Gazprom test site in the Chelyabinsk Region, were led by Gazprom’s permanent commission for the acceptance of new types of pipe products with participation from Gazprom VNIIGAZ LLC and Gazprom Gaznadzor LLC specialists.

LDPs manufactured at the Izhora Pipe Plant (part of the Severstal Russian Steel division of Severstal), on the production site in the Kolpinsky district of St. Petersburg, were subjected to these tests. The pipes were made with rolled metal produced by Severstal at Rolling Mill 5000.

The LDPs were pre-welded into a 200-meter "whip" that simulates a real gas pipeline, on which a set of measuring equipment was installed to monitor pressure, temperature and various other parameters. The preparation took several months. During the tests – especially for the experimental destruction of the initiator pipe - a training shaped charge was undermined.

For the first time in the history of conducting field tests, on the first attempt a standard mass charge failed to cope with the task. The pipe, which had an artificially applied surface incision with a depth of about 25% of the wall thickness and a width of up to 6 mm, withstood the effect of the charge. The "whip" remained intact and the pressure inside the "whip" stayed at 15 MPa. The "whip" of pipes was then re-tested, with a new charge in the same position that was 50% greater than the original. The residual wall thickness of the initiator pipe after the first explosion was already only 16.9 mm. After the second explosion, it was found that the main crack on both sides stopped with a ring within the first test pipe, 4.4 m from the annular joint with the initiator pipe. This is the best result achieved since 2008, when the first of such full-scale tests at the landfill took place in Russia. Also, for the first time, one of the two sections of the tested pipes was welded from three pipes, originally manufactured at the factory, each 18.3 m long and then cut to a length of 11.8 m. The identical results which were obtained for resistance to the spread of extended damage demonstrate the stability of the mechanical properties and the quality of rolled sheets, regardless of the length.

Source and Photo: Severstal

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