China Conducts World’s Longest Deep-Sea Corrosion Test At 10,000-Metre Depth

China State Shipbuilding Corporation has completed the world’s first 537-day deep-sea material corrosion exposure test at a depth of 10,000 metres.

The ultra-deep-sea mission tested metals, coatings and buoyancy materials under extreme underwater conditions to study how they perform during long-term exposure in one of the harshest marine environments on Earth.

Researchers said the project produced rare real-world data that could help improve the durability and lifespan prediction of future subsea infrastructure used in offshore energy, seabed mining and deep-sea exploration.

Countries and energy companies continue investing in offshore resource extraction, seabed mining technology and deep-water infrastructure, where long-term material reliability remains a major challenge.

CSSC said the test was carried out under “extremely harsh” conditions involving very high pressure, low temperatures, high salinity and extremely low oxygen levels.

At depths greater than 10,000 metres, materials face pressure more than 1,000 times higher than normal atmospheric pressure, making long-term real-world testing difficult and expensive.

Unlike laboratory simulations, the mission placed scientific instruments and materials directly on the seabed for the entire test period without bringing them back to the surface.

Researchers said this allowed the materials to remain in their natural deep-sea environment and helped produce more accurate corrosion and degradation data.

The 537-day programme studied how different corrosion-resistant materials and protective coatings performed during long-term exposure to ultra-deep-sea conditions.

According to the CSSC 725 Research Institute, the test included ferrous and non-ferrous metals, protective coatings, sacrificial anode materials and non-metallic buoyancy materials commonly used in subsea engineering systems.

Recovered samples showed major differences in corrosion resistance between coating systems.

Sun Mingxian said some coatings had already started peeling after long-term exposure, while others remained intact and would undergo further laboratory testing.

Liao Zhiqian said the recovered materials provided globally rare real-world data from a 10,000-metre deep-sea environment over an extended period.

Researchers said the environmental data collected during the mission would help improve corrosion-resistant design and lifecycle prediction for deep-sea equipment operating under extreme conditions.

The project also led to the development of new protective coating materials designed for deep-sea oil extraction and seabed mining equipment.

CSSC said the mission also improved its self-developed deep-sea simulation system, which recreates ultra-deep-sea conditions using high-pressure autoclaves and real-time environmental controls.

The updated system is expected to help researchers better compare laboratory simulations with actual deep-sea exposure data.

Researchers said the successful completion of the 537-day mission is expected to support future deep-sea exploration projects, offshore oil and gas development, and subsea mining operations requiring equipment to operate for long periods under ultra-high-pressure conditions.

References: CGTN, interestingengineering