Fire Hazards and Controls
Hot Work Permits are required for all permanent and temporary areas where such work is being performed. Permits are issued for permanent areas by Environmental Health & Safety or designated departmental Hot Work Permit Coordinators who have attended Environmental Health & Safety training, after an inspection of the area had been made. Permits are issued by the designated departmental hot work permit coordinator for all temporary areas.
Containers
Hot work shall not be performed on used containers until they have been cleaned thoroughly of any potentially flammable material and/or vapor. Pipelines or connections to the drum or vessel shall be disconnected or blanked. All hollow spaces, cavities, or containers shall be vented to permit the escape of air or gases. Purging with an inert gas may be necessary.
Confined spaces
If hot work will be performed in a confined space, additional precautions must be taken. Thoroughly testing the atmosphere for explosive gases (i.e. LEL) is critical prior to beginning welding/cutting processes. In addition to testing the top, middle, and bottom areas with a calibrated air monitor, subcompartments must also be tested for the presence of flammable gases or vapors. Under normal applications, the LEL must not exceed 10% for entry to occur. When welding or cutting will be conducted in a confined space, it is best practice for the LEL to be at 0%.
Fire blankets are made from a chemically treated material, commonly fiberglass, to render it flame-retardant. Blankets are generally used to protect other equipment, materials, or combustible building construction from sparks and slag. Overhead work where such equipment or material cannot be removed from the immediate area is one common situation where flame-retardant fire blankets are used.
Hot work, such as welding, cutting, brazing, torch-applied roofing, grinding, and soldering, produces open flames or heat which can ignite flammable and combustible materials in the vicinity. Stray sparks and hot slag can smolder for hours before igniting. Chemical pipelines, storage areas, and certain areas are of special concern where fire and/or explosion hazards may occur.
A thorough inspection of the area and scope of work should be performed prior to beginning work. Consider the following:
- Are there flammable or combustible solids or liquids on-site?
- Could flammable gases or vapors be present in the space or container?
- Is airborne combustible dust (ex. grain, wood, aluminum, or coal dust) present in the space or vessel?
- Is welding/cutting equipment free from leaks that could result in leaking oxygen or flammable gases?
The use of a hot work permitting process is one of the main controls used to reduce the risk of fire/explosion.