Welding is the process of joining metals in which coalescence is produced by heating to suitable temperatures with or without the use of a filler metal. Welding processes can be classed as pressure, nonpressure, or brazing. In nonpressure welding techniques, metal is vaporized and condenses to form a fume.

Brazing is a technique for joining metals that are heated above 800 degrees F.

"Hot work" is defined as work involving electric or gas welding, cutting, brazing, or similar flame or spark-producing operations.