Full definition
Any activity generating sparks, open flame or sufficient heat to ignite a fire or explosion in environments with flammable materials: welding, oxyfuel cutting, grinding, drilling. Requires hot work permit, atmosphere verification with gas detector (LEL <10%), removal of flammable materials within 10 m radius, 20 lb dry chemical fire extinguisher on site, fire watch and post-work revisit at 30 min. Spark temperature: up to 2,000°C. Standards: NFPA 51B (USA), ISO 45001.