The mishap occurred during the manufacturing process of Russian T-72 tank which also included filling of some gas in the tank, they said without elaborating.
A report from Theni, over 500 km from here, identified the deceased as Siva (37) who hailed from Kadamalaikundu in the southern district.
It said the family members of Siva were informed over phone by officials about his death.
He had joined the Indian Ordnance Factories, under which the HVF operates, in 2001, it added.