Section 49B(4)(b) in The West Bengal Factories Rules, 1958
(b)No oven or drier shall be taken into use in a factory for the first time unless a competent person has thoroughly examined all its parts and carried out the tests as are required to establish that the necessary safe systems and controls provided for safety in operation for the processes for which it is to be used and a certificate of such examination and tests signed by that competent person has been obtained and is kept available for examination by an Inspector at all times during working of the factory.