Iso 13920-bf [ 99% Hot ]

Note: Shape class “F” in your callout (BF) actually sits between H and K in precision, but the standard table maps B (dimensions) with F (shape) as a common combination.

| Class for dimensions | Class for shape | Description | |---------------------|----------------|-------------| | A | H | Fine (precision welding) | | B | K | Medium (standard workshop) | | C | L | Coarse (less critical) | | D | – | Very coarse (rough fabrication) | iso 13920-bf

If you have encountered the callout “ISO 13920-BF” on an engineering drawing or in a welding specification, you are looking at a standardized reference for dimensional tolerances. This article breaks down what each part of the designation means, what it requires in practice, and how it compares to other tolerance classes. What is ISO 13920? ISO 13920 is the international standard titled: “Welding — General tolerances for welded constructions — Linear and angular dimensions — Shape and position.” Note: Shape class “F” in your callout (BF)