Toolbox Talks: Hot works

Introduction

Hot Works are any operation that creates high heat or fire. This is a critical risk because it could be fatal.

It’s crucial to plan your work and obtain a permit to work.

Among the risks associated with hot works are compressed gases stored in high-pressure cylinders. Fumes and gases produced during welding tasks can damage your respiratory system or cause long term illness or cancer.

When you weld, cut, or grind, the potential for physical harm from hot metal sparks and flying chips is significant. Skin can be burned, hearing can be damaged, and ejected material can injure your eyes. Also, an electric shock can kill you.

Important facts

• An authorised hot works permit must be issued before any hot works is carried out.
• The permit must be displayed at the worksite.
• You must begin a fire watch that continues for a minimum of 2 hours after the hot works have finished.

IDENTIFY the best place to carry out hot works

Before any hot works is carried out consider:

• Potential risks around the site e.g. could ignition spread, are there flammable materials nearby? Could the fumes gather in a confined space.
  • Ensure all combustible materials are removed or at a safe distance from the hot works site.
  • Make sure any cross draughts are eliminated where possible.
  • All floor and wall openings within 10 metres of the work being conducted must be covered to prevent transmission of sparks between levels.
• Whether the work be done in a more suitable, alternative, location.
  • Improve and redesign the layout of the site if required - all wall openings need to be covered to prevent materials from escaping.
• If there an alternative means of doing the work, one that does not create heat/sparks, e.g. alternative methods such as using a cold cutting technique instead of gas cutting (for example, using hydraulic shears).
• Create an emergency plan specific to the site.
• What personal protective equipment (PPE) is required
• What firefighting equipment is required (Fire extinguishers, water, wet blankets)

ASSESS have you got the right gear?

Anyone involved in hot works must have appropriate PPE gear. The following PPE is needed when carrying out hot works:

• Cotton or fire-resistant overalls secured around wrists and neck
• Flame resistant googles
• Protective boots and gloves, appropriate for temperature expected
• Breathing devices when fumes are generated.

NB: Most high-vis vests are not flame resistant and should not be worn while carrying out hot works, unless they are flame resistant.

In addition:

• A fire extinguisher and a hose (where appropriate) must be ready to be used in an emergency.
• Establish a 'fire watch' to monitor safety during the work and for two hours after completion.
• Remember: Barricades, warning signs and spark/flash screens must be considered to protect all workers in the area.

The fire triangle

Hot work has the potential to unite all three parts of the fire triangle: oxygen, fuel, and an ignition source.

Oxygen is present in the air.

Fuel includes anything that can be ignited. Examples of common fuels include the following:

• Construction materials such as wood, plastic, insulation, roofing materials, saw dust, including those in concealed spaces.
• Flammable liquids or gases such as fuel, paint, cleaning solvents.
• Simple combustibles such as rags, paper, cardboard, furnishings.

Ignition sources can be as simple as the hot work itself. Ignition results when any heat source sufficient to ignite a fuel does so. It can occur through the direct or indirect application of heat.

• Direct application of heat includes welding, cutting, and burning.
• Indirect application includes heat conducted through metal surfaces to fuel sources on the other side (e.g. through to the other side of a bulkhead) and sparks travelling to a distant fuel source (e.g. to a pool of liquid or other combustible material).

MANAGE - leave the site safe

Explosive materials can remain dormant hours after the activity but can suddenly break into open flames.

It is recommended the site be monitored for at least two hours following any hot works.

Q and A

• See how many of the following PPE items your team can name and why they should use them:
  • Eye protection to shield against sparks, molten metal and welder's flash
  • Hearing protection
  • Clothing made of heat-resistant materials. such as a leather apron
  • Safety boots
  • Cloves made of leather or other flameproof fabric
  • Respiratory protection to protect against toxic chemicals and gases. Before you use a respirator, get proper training and have it properly fitted.
• Ask your team what is considered 'hot works'. Examples could include:
  • Brazing
  • Welding
  • Grinding work that may generate a spark
  • Oxyacetylene (steel) cutting
  • Propane soldering
  • Propane heating of butynyl membranes
  • Open flame or spark creating equipment.

Further resources

• Toolbox Talk: Power Tools
• WorkSafe NZ: Health and safety in welding