Section 73ZA(1)(xvi) in Maharashtra Factories Rules, 1963
(xvi)Cleaning of the internal surface of the heater for removing soot and check up the refactory surface on the inside shall be carried out every month, or as often as required depending upon working conditions. The coils of heater shall be removed and surface of the coil cleaned thoroughly once at least in a period of six months. The burner, nozzles, oil filters and pumps shall be cleaned once a week during the period of use.