Transneft UW Service has completed selective repairs of a defect at the main leg of the Kholmogory – Klin oil trunk pipeline’s underwater crossing of the Ob River in Tyumen Region.
A repair construction (a composite sleeve, for the “dent with a notch” defect) was installed up to the upper generatrix of the pipe during the works in the stream bed part of the river at a depth of 19 metres. For this purpose, a pit with a volume of 26 thousand cubic metres was developed. Specialists installed and dismantled the GK-25 deep submergence pressure chamber, carried out repairs at the trunk pipeline and restored insulation, lining and ballasting. The pipeline’s position was fixed by putting sandbags under it, the working pit was backfilled, and the bottom was strengthened with crushed stone.
The works were carried out by 8 specialists of a section of Transneft UW Service’s underwater operations division, including 5 divers. 5 floating vessels were used. During the works, 336 underwater descents were carried out, a total of 504 hours were spent underwater.
During the repairs, oil transportation did not stop. As a result, the bearing capacity of the section was restored to the design level.
Employees of the underwater operations division of Transneft UW Service completed the repairs with proper quality and in time in accordance with the schedule established by the plan under the guidance of the head of the section Ali Sibatullin.