En Iso 13920-bf New! Jun 2026

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.

Strong, closely spaced tack welds maintain the initial fit-up geometry before the structural passes are laid down. en iso 13920-bf

The widespread adoption of EN ISO 13920 is driven by its significant practical benefits: ISO 13920 tolerances apply to the weldment (no

The use of EN ISO 13920-BF offers several benefits and advantages, including: Strong, closely spaced tack welds maintain the initial

The designation refers to a specific set of general tolerances for welded constructions, combining two distinct classes of accuracy defined by the ISO 13920 standard . Breakdown of the Code

Clarification: The official ISO 13920 does list a class "BF." Instead, the correct notation on a drawing should be something like: "General tolerances: ISO 13920-B" or "ISO 13920 – Class B." However, in industry practice, "EN ISO 13920-BF" is widely used to denote Class B tolerances for general fabrication (F = Fabrication). For the purpose of this article, we will treat "BF" as Class B applied to welded fabrications (length, angle, flatness, and symmetry).

This specifies the allowable variations for geometric attributes such as straightness, flatness, and parallelism. Key Tolerance Areas