Second hand goods are restricted for imports under paragraph 2.17 of the Foreign Trade Policy, and may be imported only under licence. Application for licence is to be made to the Regional Authority of the DGFT in Form ANF 2B appended to the Handbook of Procedures (Foreign Trade Policy).
It is not clear whether this is re-import of exported material. If so, the provisions regarding duty and procedures wil be different. Also the intended use of the goods is not clear. Different provisions, applicable to import of second hand capital goods, could apply if the item fits the definition of 'capital goods' in the Foreign Trade Policy, extracted below:
"Capital Goods" means any plant, machinery, equipment or accessories required for manufacture or production, either directly or indirectly, of goods or for rendering services, including those required for replacement, modernisation, technological upgradation or expansion. It also includes packaging machinery and equipment, refractories for initial lining, refrigeration equipment, power generating sets, machine tools, catalysts for initial charge, equipment and instruments for testing, research and development, quality and pollution control. Capital goods may be for use in manufacturing, mining, agriculture, aquaculture, animal husbandry, floriculture, horticulture, pisciculture, poultry, sericulture and viticulture as well as for use in services sector."
Value for customs will normally be transaction value. This should be supported by a Chartered Engineer's certificate (given in the country of supply) as to the age, condition, and past and present value of the goods. If the customs reject the declared value for some reason, they would go by the manufacturer's list price after allowing depreciation. They may ask for the original invoice for this purpose.