The worker at the Indian firm's Port Talbot facility was injured as a result of spillage of molten steel which was being poured from a vessel on a crane in the continuous casting plant.
Two others workers were treated for shock after the accident on Tuesday night and all three were taken to Morriston Hospital in Swansea.
"Safety is our top priority and we will look to learn everything possible from an investigation. Our record has been ever improving to ever high levels and accidents like this are a set-back," Tata Steel spokesperson Robert Dangerfield said.
The Health and Safety Executive (HSE) for the region has been informed and they will be conducting a visit of the site this week.
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"It's an initial inquiry at the moment. An inspector will be visiting the site," an HSE spokesperson confirmed.
The injured worker was said to be in a comfortable condition in hospital recovering from the burns caused by heat, as there was no direct contact with the molten material.
His two colleagues have been discharged.
Fire and police officers were also called as part of the site's emergency plan and South Wales police confirmed the incident at the steel works had been looked into.
The spillage took place from a vessel used to feed molten metal to the continuous casting part of the Boss plant, which is where the steel is formed into continuous strands and solidifies before being cut into slabs.