To harmonize European and international manufacturing, the International Organization for Standardization (ISO) introduced ( "Welding — General tolerances for welded structures — Dimensions for lengths and angles — Shape and position" ).
Drawings would often use combined codes like "DIN 8570-BF" to indicate Class B for dimensions and Class F for geometry. Modern Equivalent: ISO 13920
±15 minutes of a degree (or approx. ±4.5 mm/m) din 8570 b pdf
It is a German national standard titled "General tolerances for welded structures; linear and angular dimensions" (Allgemeintoleranzen für Schweißkonstruktionen; Längen- und Winkelmaße). It specifies general tolerances for linear and angular dimensions on engineering drawings for welded components. If specific tolerances are not indicated on a drawing, this standard defines the permitted deviations. This allows fabricators to work efficiently within defined, customary workshop accuracies.
Source: Data derived from DIN 8570-1:1987-10. This allows fabricators to work efficiently within defined,
💡 If your drawing specifies DIN EN ISO 13920 , note that this international standard has largely superseded DIN 8570 in many regions, though the tolerance values remain very similar. Always check with your client to see which specific version they require for certification. If you'd like, I can help you: Find the current equivalent ISO standard Explain how to read a specific tolerance table Draft a compliance note for your technical drawings
For quality levels C and D, the limits are more lenient (e.g., larger porosity allowed, deeper undercut permitted). you should use
| Standard | Title | What it covers | | --- | --- | --- | | | Shape deviations on welded structures | Tolerances for angularity, straightness, flatness, and parallelism. | | DIN 8570-2 | Weld imperfections – Quality levels | Detailed classification of cracks, pores, undercuts, and incomplete penetration. |
The permissible deviation increases as the nominal length of the part increases. For example, in typical tables for Class B: Up to 30 mm: Over 1000 to 2000 mm: Over 4000 to 8000 mm: Modern Equivalent: ISO 13920 If you are working on a new design, you should use