The upstream side of Tateno Dam. Photo ©NSSC
The recently completed Tateno Dam in the Kumamoto Prefecture of Japan is designed specifically for flood control. Thick plates in duplex stainless steel SUS821L1 have played a critical role in the manufacture of hard-wearing yet lightweight equipment.
By Joanne McIntyre, Stainless Steel World
The Tateno Dam was constructed for the specific purpose of flood control. Located in the Shirakawa River Basin, an area of steep hillsides that receive higher rainfall than the national average, it has a catchment area of 383 km². The dam impounds about 36 ha of land when full, and can store 10,100 thousand cubic meters of water.
The dam has been built on the west side of Aso Caldera River, which flows through the centre of Kumamoto City, a region that has suffered from significant flood damage in the past. During normal weather conditions, water is allowed to flow freely down the river, while during heavy rainfall and snowmelt, excess water is temporarily stored at the dam to prevent flooding downstream.
Preliminary research on the dam began as far back as 1969, although construction did not start until 2018 and the dam was finally completed in March 2024.
Details at a glance
- Client: Kyushu Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism
- Project name: Tateno Dam regular spillway discharge pipe manufacturing and installation work
- Scope of project:
- Energy reduction work rectifier plate production and installation work
- Water level lowering discharge equipment construction
- Test flood gate production and installation work
- Contractor: IHI Infrastructure Construction Co., Ltd.
- Hokoku Kogyo Co., Ltd.
- Material used: SUS821L1 (NSSC 2120 ® 21%Cr-2%Ni-N) duplex stainless steel plate Approx. 1,400 tons
Thick duplex plate
Thick duplex stainless steel SUS821L1 (NSSC 2120 ® 21%Cr-2%Ni-N) plate was specified for discharge equipment in the Tateno Dam. The main body is equipped with a discharge pipe, energy reducer, rectifier plate, discharge gate, etc. to adjust the flow rate during floods and to capture driftwood and stones.
The various components of the discharge equipment (screens, pipes, gates etc) are exposed to strong water currents and impacts from rocks and other debris, making high strength and wear resistance essential. Initially, general-purpose SUS304 austenitic material was considered. However, duplex SUS821L1 was ultimately specified as this high-strength material enabled the construction of a lighter-weight design. The duplex grade is approximately twice as strong as SUS304.
The use of SUS821L1 significantly reduced construction costs as, due to its superior strength, less material was required so the equipment was lighter, while also benefitting from excellent corrosion resistance and high abrasion resistance.
Approximately 1,400 tons of SUS821L1 was used in the dam, and the selection of this material will significantly extend the lifecycle of the stainless steel components. This is the largest amount of SUS821 L1 ever used for a single project.
Combatting climate change
As heavy rains and landslides increase due to global warming, run-off dams are being built across Japan as part of the national resilience plan, leading to significant opportunities for NSSC’s SUS821L1 material. The adoption of the material for the Tateno Dam provided an opportunity to develop a material that combines high strength and wear resistance.
NSSC expects that the application of duplex stainless steel will further expand in the future.
About this Featured Story
This Featured Story appeared in Stainless Steel World June 2024 magazine. To read many more articles like these on an (almost) monthly basis, subscribe to our magazine (available in print and digital format) – SUBSCRIPTIONS TO OUR DIGITAL VERSION ARE NOW FREE.
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