Final answer:
In GMAW, non-essential variables are factors that, when changed, do not affect the mechanical properties or soundness of the weld. Examples may include the brand of equipment or color of the welding lead.
Step-by-step explanation:
In Gas Metal Arc Welding (GMAW), an essential variable is one that, when changed, could affect the mechanical properties and soundness of the weld. For procedure qualification, it is important to understand which factors are essential and which are not. While essential variables include aspects like the base material, filler material, shielding gas composition, and welding parameters (e.g., current, voltage, travel speed), there are also variables that are considered non-essential.
These non-essential variables may include factors such as the brand of the equipment, color of the welding lead, or the type of power supply (as long as it delivers the required current and voltage). The specific non-essential variable can vary depending on the welding procedure specification (WPS), however, generally, factors not directly affecting the weld's integrity may be considered non-essential.