Rublevskaya water treatment station has been operating since pre-revolution times and still remains the main source of potable water for Moscow, Russia’s largest metropolis. Today there are plenty of new materials and technologies available for water supply and water disposal which can extend pipeline operating life by up to 50 years or more. Implementation is going slowly, which is why the number of worn networks is still significant. The Rublevskaya water treatment station is no exception. Having reached a certain stage of operation, it needed restoration of its filtrate ducts – underground water mains of rectangular and circular cross-sections made of reinforced concrete. Specialists at Mosvodokanal confirmed the option to use circular cross-section plastic pipes in these conduits and ID 1400 mm and 2000 mm were approved for the various sections. They had to choose pipes and fittings for operating pressures up to 0.15 MPa, and find solutions for the following non-standard tasks:
• Installation of pipes, fittings and branching from inside, because opening of water conduits was only planned at places with bends and in chambers;
• Connection of the new pipeline to the old one;
• Pressure testing of the new pipeline conducted as for a pressure pipeline.
CORSYS PLUS pipes (pressure version) met all the requirements. These pipes fully comply with GOST R 54475 (used for the production of non-pressure pipes). In addition, they also go through an in-house pressure test similar to GOST 18599-2001 for at least 100 hours at a temperature of 20°C. This allows the use of CORSYS PLUS pipes for pressure systems with operating pressures up to 0.6 MPa. The reliability of the CORSYS PLUS pipes connections is ensured by electrofusion using special electric heaters integrated into the sockets of the pipes. This is the only type of connection that meets the requirements for a new pipeline.
Application of TRASSA-M fusion units provides automated welding: all parameters for welding are logged in automatically by reading the barcode on the pipe. This minimises the human factor at this crucial stage. The presence of a side connection made of steel along the whole length of the renovated conduits complicated the works, as did the short distance between the conduits, two of which were still in operation. This prevented the builders from expanding the problematic sections by opening the renovated conduit. For these reasons, the welding and connection work was carried out from inside. POLYPLASTIC Group’s specialists developed a unique design of connections and installation technology to deal with the issue. To ensure reliable welding of the one and a half metre connections, special pipes with thicker solid wall patches were manufactured. Well-organised first stage construction works with the participation of POLYPLASTIC Group specialists ensured flawless coordination and smooth operation on reconstruction for all three water pipelines. All preparatory works on assembling and welding were conducted by experienced personnel from the construction company, under the supervision of the chief welder. The POLYPLASTIC Training Centre successfully carried out on-site training on installation and quality control for CORSYS PLUS pipes.
Constant supervision and the availability of spare installation equipment on site (rented out by POLYPLASTIC) also significantly increased the productivity of the works. During the reconstruction of the first line of water main, this difficult task became a precise operation. Specially designed solutions for PE-Steel transition and the technology of tapping in to the new pipeline were successfully applied and passed a stringent check from technical supervision specialists at the Rublevskaya water treatment station. A special CORSYS PLUS elbow was produced for each individual bend of the conduit. Some of these had bends with a height difference, therefore the elbows were produced to accommodate the bend in two planes. Due to the confined space available for installation, the sections of elbows needed to be precisely measured and produced accordingly. Welding of the joints was carried out from inside the pipe, even when the elbows were installed using the open method. All the renovated pipelines passed through the hydraulic tests using pneumatic plugs made of special rubber.
Acceptance inspection of the joints and tests confirmed the quality of the installation and that the pipeline was leak-tight. At the final stage of installation, the gap between the walls of concrete reinforced conduits and the renovated pipelines was filled with cement mortar grout. 545 metres of CORSYS PLUS DN/ID 1400 mm and 1,246 metres of DN/ID 2000 mm pipes were used in the project. The implementation of this unique project provided an invaluable experience in trenchless reconstruction of complicated linear facilities, i.e. pressure concrete reinforced rectangular filtrate conduits for Moscow’s first water treatment station. Successful results proved the practicality and relevance of CORSYS PLUS pipes for the trenchless reconstruction of pipelines and conduits for various purposes, including highly important, non-standard projects with complicated operational needs.
Polyplastic Group Ltd.