China Yangtze Power awards 15.8 million yuan contract for in-situ AM turbine seal ring repair
China Yangtze Power has awarded Dongfang Electric Machinery a reported 15.8 million yuan (about $2.36 million) contract to develop in-situ additive manufacturing for repairing turbine runner seal rings at the Three Gorges hydropower station. The 29-month project, tender reference T261100130982, covers seal rings ranging from 8.4 to 10.9 meters in diameter across eight generator types at the plant, which has 22,500 MW of installed capacity across turbines rated at 700 MW each.
This is the second phase of a research program between the dam operator and Dongfang Electric, a subsidiary of state-owned China Dongfang Electric Group. A first-phase feasibility study already concluded that in-situ AM repair of seal rings “is technically feasible,” according to the tender. Phase II is meant to move from that feasibility finding to complete equipment sets and standardized repair procedures across all eight generator types.
| Spec | Detail |
|---|---|
| Contract value | 15.8 million yuan (~$2.36M), reported figure |
| Duration | 29 months |
| Ring diameter range | 8.4 to 10.9 meters |
| Generator types covered | 8 |
| Patent requirement | 10+ applications, including 6+ invention patents |
The current repair method requires full replacement: redesigning and casting a new ring, shipping it to the dam, heat-fitting it by interference fit, then machining it to spec, a process the tender itself calls plagued by “uncontrollable timelines, significant transportation difficulties, and a large workload for installation and machining,” with the tender separately noting that excess material removal during machining can’t be undone. The proposed alternative is a multi-machine deposition system built on-site, with modular load-bearing structures, multiple additive execution units, monitoring equipment and a dust purification system, intended to build up material directly on worn surfaces instead of swapping the whole ring.
Verification includes mechanical testing, non-destructive inspection, dimensional checks and residual-stress analysis by a third-party CMA-certified lab. The contract also requires at least one paper in a Chinese core, SCI, or EI-indexed journal. No full-scale repair has been completed yet; this round funds equipment and process development only.