ISO 13920 tolerances apply to the weldment (no external clamping force). If you force a distorted frame onto a flat table before measuring, you are cheating the inspection. Release clamps and let the part relax.

The use of EN ISO 13920-1:2014 provides several benefits, including:

This is the critical section for quality control.

This is the "Medium" class for lengths and angles. It defines the allowable deviation for measurements like the length of a beam or the degree of an angle.