China Tests Deep-Sea Cutting System For Cables And Pipelines At Depths Of Up To 3,500 Metres

China has successfully tested a deep-sea cutting system capable of operating at depths of up to 3,500 metres.

The trial was conducted during a recent expedition in 2026, where engineers validated a compact electro-hydrostatic actuator (EHA) designed for precision cutting of underwater structures, including subsea cables and pipelines.

The test was carried out by the research vessel Haiyang Dizhi 2 as part of its first deep-sea mission of the year.

The operation took place at a depth of approximately 3,500 metres under the supervision of China’s Ministry of Natural Resources.

During the mission, engineers deployed the actuator to perform cutting operations under high-pressure subsea conditions.

According to reports, the trial bridged the final gap between laboratory research and operational deployment, indicating the technology could soon be used in practical offshore scenarios.

The electro-hydrostatic actuator integrates an electric motor, hydraulic system, and control unit into a single compact device. This design removes the need for external oil pipelines typically used in conventional hydraulic systems.

Engineers involved in the project stated that eliminating external piping improves system reliability, reduces energy loss, and lowers the risk of leaks in deep-sea environments.

The actuator is also equipped with pressure compensation and corrosion-resistant features, allowing it to operate effectively under extreme subsea conditions.

The system is built to withstand pressures exceeding 35 megapascals at depth. It can deliver more than 50 kilonewtons of force while maintaining precise control during cutting operations.

The actuator also provides at least 1.0 kilowatt of drive power, enabling it to handle demanding subsea tasks such as cutting thick cables and pipeline sections.

The compact design combines multiple hydraulic components, including pumps, valves, and cylinders, into a single unit, improving operational efficiency in confined underwater environments.

The technology was developed with support from Zhejiang University as part of a project that started in 2023. It is based on systems already used in aircraft, where similar actuators control flight surfaces.

The system builds on technology already used in commercial aviation, where similar actuators control aircraft flight surfaces.

For deep-sea use, engineers strengthened the materials and improved sealing to withstand seawater and extreme pressure.

China’s previous domestic subsea cutting systems were typically limited to depths of around 2,000 metres. The newly tested actuator extends that capability to 3,500 metres, placing it within the operational range of many offshore energy and telecommunications assets.

Most subsea fibre-optic cables and offshore pipelines are located at depths between 1,500 and 4,000 metres, meaning the system could support a wide range of intervention and maintenance operations.

The new cutting system is expected to support offshore oil and gas operations, including pipeline repair, recovery, and decommissioning work. Faster and more precise cutting could reduce downtime during subsea interventions.

Engineers also said the equipment could be used to clear underwater obstacles and support other tasks such as operating seabed tools.

During the same expedition, teams tested additional equipment, including seabed sampling systems and recovery tools designed for extreme depths.

The 30-day mission involved more than 100 personnel from multiple institutions. Teams carried out over ten research tasks focused on deep-sea operations.

A remotely operated vehicle named “Haima” was also deployed to retrieve seabed instruments during the expedition. Other systems tested during the mission were designed for operations at depths of up to 10,000 metres.

Underwater cables carry most of the world’s data, and pipelines are key to energy supply. Tools that can operate at these depths are needed for maintenance and repair.

References: interestingengineering, subseacables