Arnala class was an Indian designation for the Petya III-class vessels of the Indian Navy.[1]
Although these vessels were classified as frigates in the Soviet Navy, they were classified by the Indian Navy as anti-submarine corvettes due to their role and smaller size. Vessels of the class were named for Indian islands.
INS Kiltan (P79) and INS Katchall (P81) were part of the task force for Operation Trident during the Indo-Pakistan War of 1971.[2][3]
The hulls of this class were of relatively inferior quality built only 5 m thick for use in the Baltic sea and Black seas, compared to the rest of the Navy's mostly British built ships which had 8 m thick hulls requiring the vessels to undergo major refit every 5 years to prevent corrosion. The Indian Navy constructed the Naval Dockyard at Visakhapatnam, primarily to service Russian vessels. But given the lack of engineering support from Russia there were inordinate delays in completing the servicing facility. This resulted in considerable delay of the second refit for INS Andaman (P74), which was in poor repair and subsequently was lost at sea in conditions, 140 miles (230 km) east of Visakhapatnam on 21 August 1990 around 2:03 pm, where it was conducting anti-submarine exercises with five other Indian warships. The Andaman's loss cost the navy an estimated Rs 8 crore, including the initial cost of the ship and weapons on board, as well as the lives of 15 sailors.[4][5]
The corvettes of this class constituted the 31st Patrol Vessel Squadron of the Eastern Naval Command and the 32nd Patrol Vessel Squadron of the Western Naval Command.[6]