Recently, the installation and welding of the 1000 MPa-grade penstock in the lower bend section of the No. 1 diversion inclined shaft at the Zhejiang Tiantai Pumped Storage Power Station undertaken by the company has been fully completed, marking the first successful large-scale application of this technology in China.

The Zhejiang Tiantai Pumped Storage Power Station is located in Tiantai County, Zhejiang Province, and mainly consists of an upper reservoir, a lower reservoir, a water conveyance system, an underground powerhouse, and a switch station. The station has a rated head of 724 meters, the highest in the world; a single-unit capacity of 425,000 kilowatts, ranking first in China; and upper and lower diversion inclined shafts with a length of 483.4 meters, the longest in the country. The project is surveyed and designed by East China Survey and Design Institute under Power Construction Corporation of China, with Sinohydro Bureau 12 and Sinohydro Bureau 5 undertaking the main construction tasks.

The lower bend section of the No. 1 diversion inclined shaft at the station adopts 1000 MPa-grade steel plate lining. Compared with the 800 MPa-grade high-strength steel used at the Wudongde and Baihetan hydropower stations, it presents greater construction difficulties in terms of material chemical composition, heat treatment, mechanical properties, and welding processes. The penstock components required on-site welding and installation, with a total weld length of 128.8 meters and a pipe wall thickness of 54 millimeters. Through meticulous research, the PowerChina team overcame the welding technology for ultra-high-strength steel pipes under high-humidity conditions, filling a domestic technical gap, achieving a one-time acceptance pass rate of 100%, and holding great significance for the promotion and application of ultra-high-strength steel pipes in pumped storage and other industries.

The smooth completion of the installation and welding of the 1000 MPa-grade penstock at the Zhejiang Tiantai Pumped Storage Power Station marks that the company has fully mastered the installation technology for 1000 MPa-grade penstock and welding environment treatment technology, laying a solid foundation for large-scale promotion and application in hydropower projects.

The Zhejiang Tiantai Pumped Storage Power Station is a key implementation project under the National Medium- and Long-Term Development Plan for Pumped Storage (2021–2035), with a total installed capacity of 1.7 million kilowatts. After completion, the station is expected to generate 1.7 billion kilowatt-hours of electricity annually, save about 520,000 tons of coal, and reduce carbon dioxide emissions by about 1.04 million tons, which is of great significance for optimizing the power source structure, improving the safe and stable operation capability of the power grid, and achieving the "dual carbon" goals.