Two workers died inside a tank on a trailer last month, prompting an investigation by Workplace Health and Safety Queensland.
Inspectors believe that the trailer last transported a mix of sugar cane by-product and urea.
The 2 workers were cleaning inside the tanks after unloading it earlier.
Workplace Health and Safety Queensland reminded all workplaces about the risks of working in confined spaces and obligations under state safety laws for both employers and employees.
Get more information at worksafe.qld.gov.au