Iso | 13920 Bf

| Nominal length/width (mm) | Permitted deviation (mm) | |--------------------------|--------------------------| | up to 400 | 0.5 | | >400 to 1000 | 1.0 | | >1000 to 2000 | 1.5 | | >2000 to 4000 | 2.0 | | >4000 to 8000 | 3.0 | | >8000 to 12000 | 4.0 |

| Nominal size range (mm) | Permitted deviation (± mm) | |------------------------|----------------------------| | up to 30 | 0.5 | | >30 to 120 | 1.0 | | >120 to 400 | 1.5 | | >400 to 1000 | 2.0 | | >1000 to 2000 | 2.5 | | >2000 to 4000 | 3.5 | | >4000 to 8000 | 5.0 | | >8000 to 12000 | 6.5 | iso 13920 bf

Introduction In welding fabrication, achieving perfect dimensions is often impractical and cost-prohibitive. ISO 13920 is the international standard that specifies general tolerances for linear and angular dimensions, as well as for straightness and flatness, of welded structures. | Nominal length/width (mm) | Permitted deviation (mm)

Note: Some drawings use "BF" as a shorthand for "Fine overall" – but strictly per ISO 13920, you must verify if they mean linear class F + angular class B. Occasionally, "BF" is used to mean "Class B – Fine" for both, but that is non-standard. Always confirm with the drawing's tolerance block. Occasionally, "BF" is used to mean "Class B