What is defined as a non-essential variable under ASME code?

Under the ASME code, a non-essential variable is defined as a variable that does not affect the mechanical properties of the weld. This means that changes or variations in these variables are not expected to have a detrimental effect on the integrity and performance of the welded structure.

Non-essential variables can generally include aspects such as certain dimensions of the welding procedure that, while relevant, do not directly influence the final product's strength, ductility, or toughness. The purpose of classifying variables into essential and non-essential categories is to streamline the qualification process by allowing for some flexibility in non-essential aspects without compromising quality assurance.

In contrast, essential variables are critical, as they directly influence welding integrity and performance, requiring reevaluation of the welding procedure if they change. This distinction is crucial for ensuring that the necessary standards are met while maintaining efficiency in the qualification process.