Successful installation of 1000 MPa-grade high-strength steel pressure pipes for the first time on a large scale in the country

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Recently, at the Zhejiang Tiantai Pumped Storage Power Station, which was designed and constructed by China Power Engineering Group – and features the largest single-unit capacity in China, the longest inclined shafts in its water intake system, and the highest rated head in the world – the installation of 1000 MPa-grade high-strength steel pressure pipes and steel branch pipes was completed for the first time on a large scale in China. This marked a breakthrough across the entire value chain, from research and development to construction, in terms of new materials and new manufacturing processes. It has set an industry benchmark for the localization of high-end equipment. The Tiantai Pumped Storage Power Station is located in Tiantai County, Taizhou City, Zhejiang Province, and consists mainly of an upper reservoir, a lower reservoir, a water transfer system, an underground power house, and a substation. During the project construction, multiple domestic and world records will be broken. Among them, the capacity of each power plant unit is 425,000 kilowatts, the highest in the country ； The length of the upper and lower water diversion inclined shafts is 483.4 meters, making it the longest single-stage inclined shaft in China ； The rated head is 724 meters, the highest in the world. The design strength of the pressure pipes in rooftop pumped storage power stations reaches 1000 MPa, requiring extremely high standards in material development, welding techniques, and construction precision. The project team, in collaboration with the owner, design firms, and research institutions, made full use of the innovative ecosystem spanning research and development, manufacturing, and application. Over a period of nearly two years, they overcame three major technical challenges: first, innovation in materials and processing techniques, which involved addressing the compatibility issues between domestically produced high-strength steel plates and welding materials; more than 100 sets of welding process evaluations were conducted to ensure that the strength of the welds matched that of the base material. Secondly, there have been advances in construction technology; in the highly humid conditions of tunnels and within complex confined spaces, an innovative approach of \"regional environment control + precise welding inside the tunnel\" was adopted to address the issue of hydrogen-induced cracking sensitivity in high-strength steel, resulting in a 100% first-pass acceptance rate for welds. Third is the localization verification: for the first time, two domestic welding electrodes were used for the entire welding process, and their performance parameters met all the required standards, successfully breaking the foreign technological monopoly. The successful use of 1000 MPa-grade steel pipes at the Tiantai Pumped Storage Power Station has not only significantly reduced the construction costs of high-head power stations, but also effectively shortened the construction time by reducing the weight of the steel branch pipes and the amount of welding required. The application of this technology provides critical technical support for the construction of large-scale, high-difficulty hydropower stations both domestically and internationally.