Fatal Hot Work Incident

19 Sept

In a recent incident, a person died when a drum exploded unexpectedly at a property. Initial investigations indicate the person was using the drum as a work platform while undertaking welding activities. Investigations are continuing.

IMPORTANT: These findings are not yet confirmed, and investigations are continuing into the exact cause.

Safety Issues

'Hot work' is any process involving grinding, welding, brazing, oxycutting, heat treatment or any other similar process that generates heat or continuous streams of sparks. Undertaking hot work in areas where flammable or combustible chemicals or materials are present, could create a significant risk of fire or explosion.

Conducting hot work that involves containers such as drums, tanks and pipes that have not been properly decontaminated is a common cause of serious incidents. Even if a drum or container is considered to be empty, and has been empty for a long time, flammable residues and vapours can still remain and be a risk of explosion when high heat is applied. Simply rinsing drums or containers is not a fail-safe way to remove oily residues or flammable vapours.

Even very small quantities (millilitres) of flammable or combustible substances (including diesel and oils) within a closed drum or fuel tank on which hot work is conducted can have catastrophic impacts. Heated residues expand and pressurise the container to the point of failure leading to a significant release of energy that can cause harm to people and property.

Containers of concern are not just fuel and oil containers. Some chemical formulations such as agricultural chemicals may also include flammable or combustible solvents presenting similar fire or explosion risks with their containers.

Possible Control Measures to Prevent Similar Incidents

The Work Health and Safety Regulation 2011 requires specific controls for prevention of fire and explosion risks associated with hazardous chemicals. These include:

s51 - A PCBU a workplace must manage risks to health and safety associated with a hazardous atmosphere at the workplace and;
s52 - A PCBU a workplace must manage risks to health and safety associated with an ignition source in a hazardous atmosphere at the workplace.

A PCBU must manage risks to health and safety associated with a hazardous atmosphere. This includes identifying all sources of ignition, such as welding, hot-cutting, and grinding, which generate heat, flames, and sparks, that could cause an ignition of flammable and combustible substances.

You must also ensure that flammable or combustible substances in the workplace are kept in the lowest practicable quantities. This includes gas cylinders and waste liquids in containers, whether empty or full.

A safe system of work should be implemented to manage the fire and explosion risks associated with ignition sources and hot work activities on and around containers that may have contained flammable or combustible liquids. This can include:

Developing and implementing specific safe work procedures that should include a hot work permit system to control when and how hot work is undertaken. More information can be found in the following Australian Standards:

Obtaining the current safety data sheet (SDS) from the manufacturer, importer or supplier of the chemical in the container or system to be worked on and making the SDS readily available to workers.
Ensuring you keep a hazardous chemicals register for use by workers. A hazardous chemicals register is a list of hazardous chemicals stored, handled or used at a workplace.
Checking what has previously been stored in the empty drum or container by reading the label and reviewing the SDS for the hazardous chemical and assessing the information provided on the safe storage and handling. If it has been found to contain flammable or combustible substances, seek to properly dispose of the container and avoid any hot work on it.
Be wary of any container that is not correctly labelled (e.g., label has been removed or has become illegible) or has an unknown history.
Be wary of ‘waste’ oil containers which may also hold an unknown amount of flammable liquid presenting a flammability hazard that has not been recognised.
If there is no alternative but to perform hot work on the container, remove all traces of flammable or combustible materials from the container to ensure it is properly cleaned of residues and vapours and certified.
Sparks and hot slags ejected from hot work can travel several metres. Fire resistant barriers should be used to prevent these ignition sources from reaching other areas where flammable and combustible materials are located to remove the risk of these materials being ignited.
Do not use drums as a welding or work platform.
Store used empty drums with bungs removed in a well-ventilated place away from other work areas. Removing the bung will not guarantee all hazardous residues and vapours have been naturally vented.
Keeping and maintaining fire-fighting equipment nearby.
Providing workers, including experienced workers with information, instruction, training and supervision on fire and explosion hazards. Ensure the competency aligns with the requirements and complexity of the task (workers must be trained and have the appropriate skills to carry out a particular task safely).