BlueScope Steel will begin blast furnace maintenance work on Wednesday, and warn nearby residents that it may result in loud noises and emissions from the Port Kembla plant.
The maintenance program is expected to take about 10 days.
BlueScope Steel's general manager of manufacturing John Nowlan said it was possible the community would hear noise and emissions from No 5 blast furnace this week and next week but it was a normal part of the process.
Mr Nowlan said the maintenance project was significant and represented more investment by BlueScope Steel in the Illawarra.
About 450 contractors will be on site to perform the work and the most likely times for noise or emissions was on Wednesday or late next week.
"As the blast furnace is run down in the lead-up to the maintenance and when the furnace starts up after the maintenance period, there is potential for some visual emissions or loud noises to occur," Mr Nowlan said.
"If this does happen, we urge people not to be alarmed as it is part of the normal process of ramping up the furnace to a sufficient and stable temperature at which the hot metal can be processed into steel."
Mr Nowlan said the latest work followed successful maintenance shutdowns in January and May.
"Our No 5 blast furnace will again be undergoing similar repairs and maintenance over the coming two weeks," he said.
"The scheduled maintenance is to undertake assessment and repairs on the asset, including a program to change out wearing staves."