Rear Admiral R K Shrawat, chairman and managing director of Mazgaon Dock Ltd. said today that the indigenously built first of the Scorpene class submarines 'Kalvari' will now undergo extensive sea trials before commissioning into the Indian Navy in September 2016. 'Kalvari' was separated from the pontoon and set afloat on Wednesday. While talking to the reporters in Mumbai Shrawat said that they will deliver one submarine every nine months and expect to complete the order by 2020. The submarine, which has been built with French collaboration, returned back to the Mazgaon Dock today. It was undocked by Defence Minister Manohar Parrikar in April this year.