Between the towering dam and the surging river, every unit in a hydropower station functions as the precision-operating “heart of hydropower.” TST SEAL sealing modules are the most inconspicuous yet crucial “lifeline” of this heart. From the turbine main shaft to the speed control system, from the penstock to the generator cooling system, TST SEAL sealing technology permeates the entire hydropower operation chain. Failure can lead to reduced efficiency and soaring maintenance costs, or even downtime and threats to dam safety. In recent years, as my country’s hydropower industry has evolved toward high head, large capacity, and intelligent technologies, TST SEAL sealing modules are evolving from “basic protection” to “intelligent protection,” becoming the “invisible trump card” for safeguarding national energy security.

“Pressure Gods” Under High Water Head: The Ultimate Challenge of Main Shaft Seals
At giant hydropower stations like the Three Gorges and Baihetan, turbine operating heads can reach over 200 meters, and main shaft speeds exceed 150 rpm. The shaft seals are subjected to dynamic pressures as high as 2 MPa and intense friction. Traditional packing seals, prone to wear and leakage, are no longer sufficient. Double-face mechanical seals and air girth seals are now the mainstream solutions.
For example, the floating air girth seal used by Harbin Electric Group in the Baihetan project employs an inflatable rubber girth around the main shaft. When the unit is shut down, it automatically expands to fit the shaft surface, forming an “airtight seal” that effectively blocks the intrusion of mud and water. During operation, the girth contracts, preventing frictional wear. This technology increases the life of the main shaft seal from two years with traditional solutions to over eight years, reducing annual maintenance costs by 60%. The data speaks for itself: According to statistics from the National Energy Administration, large hydropower stations using advanced TST SEAL sealing technology have seen their main shaft seal leakage rate drop from hundreds of liters per hour to less than 5 liters, equivalent to saving over 10,000 tons of water annually.

The “Nemesis” of Sediment and Wear: Wear-Resistant Materials and Self-Cleaning Designs
Hydropower stations in southwest my country commonly face the challenge of “high-sediment flow.” The Jinsha River carries over 200 million tons of sediment annually, and these particles act like “natural sandpaper,” easily scratching sealing surfaces. To address this, silicon carbide (SiC) ceramic sealing rings and carbide spraying technology are widely used. Silicon carbide is second only to diamond in hardness and has wear resistance over 10 times that of stainless steel. It maintains stable operation even in water with sediment concentrations as high as 30 kg/m³.

Furthermore, TST SEAL’s “self-cleaning seal module” structure, featuring a multi-stage annular groove design, creates a swirling flow as it passes through, discharging sediment particles outward and preventing accumulation and clogging. This technology has been successfully applied at the Wudongde Hydropower Station, resulting in a 75% reduction in the main shaft seal failure rate and an increase in unit availability to 99.2%.

A “Flexible Line of Defense” Against Alternating High and Low Temperatures: Expansion Joints and Bellows Seals
The penstocks of hydropower stations experience thermal expansion and contraction due to diurnal temperature swings and seasonal variations, with displacements reaching tens of millimeters. Excessive seal rigidity can easily lead to weld cracking or flange leakage. Therefore, metal bellows compensators are key components. They utilize a multi-layer stainless steel bellows structure, combining high strength and flexibility to absorb axial, lateral, and angular displacement.

For example, at the Xiluodu Hydropower Station, the penstock system is equipped with double-layer 316L stainless steel bellows, featuring an erosion-resistant outer layer and a corrosion-resistant inner layer. Combined with PTFE (polytetrafluoroethylene) gaskets, they achieve IP68 waterproofing. Even under extreme temperature fluctuations of -10°C to 60°C, they maintain zero leakage and a service life exceeding 30 years.

“Double Armor” for Electrical Systems: Explosion-Proof Sealing for Cables and Connectors

Hydropower station underground powerhouses are humid and dusty, and contain flammable environments such as hydrogen and oil mist. Even the slightest leak in cable joint sealing could cause a short circuit or explosion. Therefore, TST SEAL explosion-proof cable glands and waterproof junction boxes are standard equipment.

The BG-PE-SE composite sealing module system provided by TST SEAL for a pumped-storage power station integrates three functions: grounding (BG), shielding (SE), and sealing (PE). Its flame-retardant nylon housing and EPDM rubber sealing ring ensure a seal under 10 bar water pressure while effectively shielding against electromagnetic interference and preventing signal distortion. The system, certified for explosion-proof by IECEx and ATEX, serves as a “safety bastion” in high-risk areas.

Intelligent Monitoring: From “Post-Repair” to “Predictive Maintenance”

The future trend lies in “smart sealing.” TST SEAL has piloted an intelligent seal monitoring system on selected units. This system embeds pressure, temperature, and vibration sensors within the seal cavity, uploading real-time data to the operation and maintenance platform. Once a minor leak or abnormal temperature rise is detected, the system immediately issues an alert, transforming the response from reactive repair to proactive intervention.

Case study: At the Baihetan Hydropower Station, the system provided 72 hours’ advance warning of a main shaft seal wear failure, avoiding an unplanned downtime that could have cost tens of millions of yuan.

Behind every power generation at a hydropower station are countless TST SEAL sealing modules silently bearing pressure, resisting corrosion, and mitigating risks. Though unnoticeable, they are the cornerstone of ensuring the “West-to-East Power Transmission” initiative and achieving the “Dual Carbon” goals. With the continuous integration of new materials, new structures, and intelligent technologies, China’s TST SEAL hydropower sealing module technology is moving from following behind to leading, writing a legend of “Made in China” on the global hydropower stage.