In a significant step forward for India’s Deep Ocean Mission, the Indian Space Research Organisation (ISRO) has completed the first welding of two crucial rings forming the personnel sphere of the MATSYA-6000 submersible. The crewed deep-sea vehicle is designed to dive up to 6,000 meters beneath the ocean surface. It is part of the ‘Samudrayaan’ project, led by the Ministry of Earth Sciences (MoES).
The project is a joint effort between ISRO’s Vikram Sarabhai Space Centre (VSSC) and the National Institute of Ocean Technology (NIOT), also under MoES. Together, they are developing a specialized spherical hull that will serve as the pressurized compartment for human occupants during deep-sea missions.
The titanium alloy sphere has a diameter of 2.26 meters and a wall thickness of 80 millimeters. Known for its high strength and corrosion resistance, the alloy allows the structure to endure pressure levels up to 600 bar and temperatures as low as -3°C. The sphere is designed to accommodate a crew of three during deep-sea explorations.
One of the most complex engineering challenges in the project has been the development of an advanced Electron Beam Welding (EBW) process, capable of joining thick titanium plates (up to 102 mm). To meet this need, ISRO’s Liquid Propulsion Systems Centre (LPSC) in Bengaluru upgraded its EBW facility from 15kW to 40kW.
Over 700 welding trials were conducted to fine-tune the welding parameters, ensuring optimal strength and durability of the joints. For quality assurance, ISRO also enhanced its X-ray radiography capabilities, achieving one of the highest energy levels used for non-destructive evaluation (NDE) in the country, to meticulously inspect the integrity of the welds.
The achievement marks a key milestone in India’s efforts to establish indigenous capabilities in deep-sea exploration and further advances the development of the country’s first human-occupied deep-ocean submersible.