AWS Certified Welding Inspector — FundamentalsSafetyMedium
A welding inspector is reviewing the fire prevention plan for a construction site where extensive hot work, including welding and cutting, is scheduled. The plan specifies that a fire watch is required when hot work is performed within 35 feet of combustible materials. According to NFPA 51B, what is the maximum distance from the hot work operation that combustible materials must be removed or protected before a fire watch is required?
- A50 feet (15.2 meters)
- B10 feet (3 meters)
- C35 feet (10.7 meters)
- D20 feet (6 meters)
Show answer & explanationAnswer & explanation
Correct answer: C. 35 feet (10.7 meters)
NFPA 51B, 'Standard for Fire Prevention During Welding, Cutting, and Other Hot Work,' specifies that a fire watch is required if hot work is performed in an area where combustible materials are within 35 feet (10.7 meters) of the hot work operation. This distance ensures that sparks and slag do not ignite nearby materials.
Why the other options are wrong
- A. 50 feet is a greater distance than the minimum required by NFPA 51B for fire watch initiation, though it might be prudent in some high-risk situations.
- B. 10 feet is too close for adequate protection against sparks and slag in many hot work scenarios.
- D. 20 feet is insufficient; NFPA 51B requires a larger radius for fire watch.
Hot Work Fire Watch Distance
According to NFPA 51B, a fire watch is required when hot work is performed within 35 feet (10.7 meters) of combustible materials, or if combustibles are adjacent to partitions, walls, or ceilings that can conduct heat.
- 35 feet is the minimum radius for fire watch initiation.
- Combustibles must be removed or protected if within this distance.
- Fire watch personnel monitor for fires during and for a period after hot work.
- NFPA 51B is the governing standard for hot work fire prevention.
Memory trick: Hot Work's 35-Foot Rule: Clear the zone or get a fire watch to zone in!