The works on laying a siphon — a section of the Kuybyshev — Tikhoretsk oil trunk pipeline of Transneft Volga underneath the Bolshoy Karaman River in Saratov Region — have been completed.
The construction of the pipeline’s underwater crossing began in November last year as part of Transneft’s technical upgrading programme. The technical customer is Transneft PCD.
The goal is to increase the throughput capacity of the Samara – Zenzevatka section (the Kuybyshev – Tikhoretsk OTP) to 40 MTPA. At present, the maximum throughput capacity of the pipeline is 35 MTPA.
By now, the set of works on laying the siphon with a total length of 311 metres underneath the river bed (the water surface width is 23 metres) has been completed. The total length of the underwater crossing section, taking into account the bank, is 1,175 metres. The diameter of the pipe is 1,020 mm. A trench for laying the siphon along the bottom of the river took 2.5 months to dig out using excavators with an extended boom mounted on pontoon boats. About 38 thousand m3 of underwater soil were removed.
Before the pipeline was laid, hydraulic testing and a diagnostics were carried out by an in-line inspection tool using the dry pigging method. The inspection revealed no defects.
Before the laying, continuous lining of the siphon with wooden slats was made, followed by installation of ferroconcrete annular weights. The weight of one set is 4,100 kg, the total weight of the siphon with weights is more than 470 tonnes.
The construction and installation works are still underway at the underwater crossing. The stream bed sections of the pipeline are being welded, the trenches for the bank parts of the crossing are being dug out. Two bank stop valve units will be also installed as part of the project.
The works at the facility are to be completed in October 2020.