Fire Blankets & Spark Containment

Welding, cutting and grinding throw sparks and slag that can travel far, fall through cracks and smolder for hours before turning into a fire. Fire-resistant blankets and curtains catch and contain them, and protect nearby surfaces from heat. They are an important layer of protection, but they don’t replace permits, a fire watch or common sense.

• Welders & Cutters
• Roofers
• Maintenance

Types of blankets and covers

Check each product’s rating and limits, such as the continuous temperature, the type of exposure (sparks, spatter, heavy slag) and the standards it meets. Blankets for light spatter won’t survive heavy cutting. Buy from reputable makers and follow the instructions. See Buying PPE.

Where blankets fit in hot work safety

• Hot work permits and procedures come first. See Hot Work Permits.
• OSHA and NFPA 51B require that combustibles within 35 feet (about 11 meters) of hot work be moved or protected. If they can’t be moved, cover them with fire-resistant blankets or shield them, and seal floor and wall openings. See Welding & Cutting and NFPA 241 Construction Fire Safety.
• A fire watch is still required where there is a fire risk, during the work and afterward (typically at least 30 minutes, longer under some codes). See Sparks & Fire Risk.
• Blankets limit the spread of sparks, but not heat conduction through metal, so combustibles on the other side of a wall or pipe may still ignite. Watch hidden spaces. See Hot Work in Occupied Buildings.

Using blankets properly

• Choose the right blanket for the heat, slag and spark load, and check that it’s clean, dry and free of holes. Use a heavier type for overhead work, cutting and gouging.
• Cover floors and surfaces below the work. Sparks fall far and bounce, and can drop through gaps in decking, grating and floor openings. Cover openings in floors and walls with blankets or non-combustible materials, and seal cracks.
• Overlap edges, and make sure there are no gaps. Sparks can slip through seams.
• Secure blankets with clips, magnets, grommets and tie-downs, so wind, drafts and movement don’t blow them off. Use a hanging system for vertical curtains, with weight at the bottom.
• Protect people and equipment. Cover nearby electrical equipment, cables, hoses, gas cylinders, wiring, flammable liquids and finished surfaces. Use blankets to protect cables from slag.
• Protect both sides of walls and floors if work can ignite things on the other side.
• Keep blankets at a safe distance from the arc or flame, as the rating indicates. A blanket draped on a hot object can burn.
• Cover roofing and ceiling work and protect insulation, wood framing and membranes. See Torch-Applied Roofing.
• Combine blankets with other controls: removing combustibles, wetting down (where appropriate and safe), fire extinguishers, and a trained fire watch. See Fire Extinguishers.

Limits and mistakes

• Don’t use a blanket as the only protection for combustibles close to heavy cutting or grinding.
• Don’t use damaged, oily, wet or greasy blankets. Oil can burn, and wet blankets can steam or conduct electricity.
• Don’t use plastic tarps, canvas or ordinary fabric. They melt or burn. Only use materials designed and rated for hot work.
• Don’t leave blankets near the arc where they could touch hot slag for long periods beyond their rating, and don’t drape them over electrical gear that is in use.
• Don’t forget the cleanup. Slag and sparks can hide under and around blankets. Inspect and clear it.
• Avoid breathing dust from damaged blankets. Some contain refractory fibers or silica. Handle with care and wear a respirator when brushing off or cutting them. See Silica.
• Don’t use blankets to mask a gas leak or a hazardous atmosphere. Test for flammable gas first. See Flammable Gas Detection.

Inspection, storage and disposal

• Inspect before each use: holes, burn-through, frayed edges, loose fibers, damaged grommets, oil or chemical contamination, brittleness and failure of the coating. Discard damaged blankets or repair only as the maker allows.
• Clean as directed and shake off slag. Don’t fold a blanket with hot slag trapped in it.
• Store flat or rolled in a dry, clean place away from oil, chemicals and sunlight.
• Replace on schedule and track the age and use of blankets in your program.
• Dispose of worn blankets according to local rules.

Small-fire blankets

• Cooking fires: a fire blanket can smother a small grease or pan fire if you can cover it completely and safely. Turn off the heat, hold the blanket like a shield, lay it over the pan and leave it. Don’t use water on grease fires. See Kitchen Safety.
• Clothing fires: wrapping a person with a fire blanket can smother the flames, but the first response is still stop, drop and roll. Get medical care for burns. See Burn First Aid.
• A blanket is not a substitute for calling 911 or using an extinguisher on larger fires. Evacuate when a fire grows. See Fire Extinguishers.

Fire blanket checklist

• A hot work permit is in place and combustibles within 35 feet are moved or covered
• The blanket is rated for the heat, slag and sparks of this job, clean, dry and undamaged
• Floors, walls, openings and equipment are covered with overlapping edges, secured against wind and movement
• The other side of walls and floors is checked, and a fire watch is assigned
• Extinguishers are ready; no plastic tarps or unrated materials are used
• Blankets are inspected, stored properly and replaced when worn

Last updated: October 5, 2026