Hydropower stations and pumped storage industry

Electrical energy is the core driving force behind the operation of modern society. As a clean, renewable, stable, and reliable green energy source, hydropower serves as the cornerstone for optimizing and upgrading China’s energy structure—and it is also a vital foundation for achieving the “dual carbon” goals and ensuring energy security. The hydropower industry focuses on harnessing the potential and kinetic energy of water flow to generate electricity. By constructing key facilities such as river‑damming barrages, water diversion systems, and powerhouses, it enables the efficient, energy‑based utilization of water resources while simultaneously delivering multiple benefits, including power generation, flood control, irrigation, water supply, and ecological regulation. Hydropower is an important component in the coordinated advancement of national energy infrastructure development and ecological civilization building.

China has built numerous hydropower stations, ranking first in the world in both quantity and installed capacity. Based on water resource conditions, project scale, and functional positioning, these stations can be categorized into three major types: large-scale conventional hydropower stations, medium‑ and small‑scale conventional hydropower stations, and pumped storage power stations, thereby establishing a three‑dimensional layout characterized by “large-scale projects taking the lead, medium‑ and small‑scale projects providing complementary support, and pumped storage working in synergy.” Among them, large‑scale conventional hydropower stations—such as Three Gorges, Baihetan, and Lianghekou—are primarily located along the main streams of the major rivers in Southwest China.

Hydropower station projects integrate core technologies from multiple fields, including hydraulic engineering, mechanical manufacturing, electrical engineering, materials science, and automated control, placing extremely high demands on engineering design, construction techniques, and equipment quality. During construction, engineers must tackle a multitude of challenges, such as complex geological conditions—like high mountain canyons, fault zones, and water inrush—as well as extreme weather. Safe construction relies on advanced technologies like proactive geological forecasting, large-scale equipment lifting, and high‑strength concrete placement. Among these, pressure steel pipelines serve as the core conduits of hydropower station water intake and power generation systems, playing a critical role in conveying high‑pressure water flows and transmitting hydraulic energy. They act as the “lifeline” connecting the dam, water diversion tunnels, and generator units, and their operational status directly impacts the safety, stability, and power generation efficiency of the hydropower station. As a core supporting component of the pressure steel pipe system in hydropower stations, bellows expansion joints are specially designed to meet the operational requirements of pressure steel pipes. They play a crucial role in absorbing thermal expansion and contraction displacement of the steel pipes, alleviating stress caused by geological settlement and机组 (unit) operating vibrations, compensating for installation errors, and preventing leakage of high‑pressure water flow. These joints are a key link in ensuring the safety of the pressure steel pipe system and extending the service life of equipment, directly impacting the overall operational reliability of the hydropower station.

The core requirement of hydropower stations is to achieve safe, efficient, and stable conversion and transmission of hydropower. This requirement spans the entire lifecycle of project design, construction, and operation, placing stringent demands on the reliability, high-pressure resistance, corrosion resistance, and vibration resistance of supporting equipment. Among these, pressure steel pipe systems—and their associated equipment—serve as a critical link, directly determining both the operational safety and power generation efficiency of hydropower stations.

Hydropower station penstocks are subjected to high-pressure, high-velocity water flow for extended periods, while simultaneously enduring multiple challenges such as temperature fluctuations (including diurnal and seasonal variations), geological settlement, vibration caused by unit operation, and erosive corrosion from water flow. These conditions make the penstocks prone to issues like deformation, joint leakage, and stress concentration leading to fracture—problems that, in severe cases, can result in shutdowns for maintenance or even trigger safety incidents. As the “flexible protective component” of the pressure steel pipe system in hydropower stations, expansion joints play a core role in adapting to the operational characteristics of pressure steel pipes, compensating for thermal expansion and contraction caused by temperature variations, cushioning vibration stresses induced by unit operation and water flow impacts, mitigating tensile or compressive damage to the steel pipes resulting from geological settlement, while simultaneously ensuring tight sealing at the joints to prevent high‑pressure water leakage. This guarantees the continuous and stable operation of the pressure steel pipe system, making expansion joints an indispensable core piece of supporting equipment for hydropower stations.

In light of the operational characteristics of pressure steel pipes in hydropower stations, the appropriately matched bellows expansion joints must meet the following core requirements: First, it boasts excellent high-pressure resistance, capable of withstanding the loads imposed by high‑pressure water flows in hydropower stations—typically reaching tens of megapascals—while completely eliminating deformation and leakage under high pressure. Second, it is highly corrosion‑resistant and erosion‑proof, able to withstand the erosive and corrosive effects of media such as freshwater and sediment-laden water, while also resisting the damaging effects of outdoor and underground damp environments, thereby ensuring a long service life (generally required to match that of the pressure steel pipe, with a minimum service life of 30 years). Third, it exhibits strong vibration and fatigue resistance, capable of enduring the continuous vibrations generated during unit operation and preventing component damage caused by prolonged vibration. Fourth, it offers strong adaptability, allowing for flexible customization based on the specifications, pressure ratings, displacement requirements, and installation scenarios of pressure steel pipes—for example, horizontal sections, vertical sections, or bends—thus meeting the personalized needs of various types of hydropower stations, including large conventional hydropower plants, small and medium-sized hydropower stations, and pumped storage power plants. Fifth, it features outstanding sealing performance, employing high‑quality sealing structures to ensure zero leakage under high‑pressure water flows and to safeguard power generation efficiency. As the industry undergoes intelligent upgrades, bellows expansion joints must also integrate intelligent monitoring capabilities, embedding sensors to provide real‑time feedback on operating conditions and offer data support for the operation and maintenance of hydropower station equipment.