A major engineering milestone has been reached at the Jinsha River Xulong Hydropower Station, with the successful hoisting of the spiral case for Unit 2. The component, weighing 284 tonnes, was lifted into place following a 36-day assembly and welding process, marking a critical breakthrough in the project’s electromechanical large-equipment installation phase.
According to information released on September 1, the project is being developed by the National Energy Group and constructed by the Bureau of Hydropower and Water Resources No. 7. The spiral case serves as the core load-bearing foundation for the hydro-generator unit, supporting the unit's self-weight, axial loads, and water pressure, and represents a key control procedure in the electromechanical installation sequence.
The 284-tonne spiral case arrived at the site in four segments, with the project team completing the entire process of assembly, welding, and hoisting in 36 days. To address the challenge of controlling welding deformation in large components at high altitude, the team optimised the assembly and welding techniques, achieving a 100% first-pass acceptance rate in weld flaw detection.
"During construction, we innovatively applied intelligent monitoring of welding deformation, which allowed us to optimise welding procedures in real time. This not only achieved reverse deformation control during the welding of the spiral case but also shortened the assembly period from 50 days to 31 days," said Yang Ping, Chief Engineer of the Xulong Electromechanical and Metal Structure Installation Project Department of Bureau of Hydropower and Water Resources No. 7. He further explained that intelligent monitoring technology was also adopted for the installation of embedded parts, enabling precise monitoring throughout the concrete pouring process for the draft tube and effectively preventing displacement issues. The same technology will continue to be applied to the second-stage concrete pouring monitoring of the volute casing.
Progress updates indicate that the volute casing hoisting for Unit 1 at the Xulong station has been completed, with the exception of the closure sections. Excavation and support work on the left and right dam abutment slopes is largely finished, while underground cavern excavation and support on the right bank are nearing completion. Additionally, five concrete pours for the dam have been completed.
"According to our annual plan, we will complete the handover of the volute casing workspaces for Units 1 and 2, as well as the assembly, welding, and hoisting of the spiral cases for Units 3 and 4, within this year," added Yang Ping. He stated that the team will continue to closely monitor critical milestones to ensure the annual targets are met on schedule, laying a solid foundation for the early commissioning and power generation of the station.
The Jinsha River Xulong Hydropower Station is situated across Derong and Batang counties in the Garze Tibetan Autonomous Prefecture of Sichuan Province, Dechen County in the Diqing Tibetan Autonomous Prefecture of Yunnan Province, and Mangkang County in the Chamdo region of the Tibet Autonomous Region. It is the largest hydropower station approved for construction during China's 14th Five-Year Plan period, featuring four vertical-shaft Francis turbine-generator units with a total installed capacity of 2,400 megawatts, and serves as a key backbone power source for the West-to-East Power Transmission project.
Once completed, the station is expected to generate approximately 10.5 billion kilowatt-hours of electricity annually and save 3.15 million tonnes of standard coal, contributing significantly to regional clean energy supply and green development.