This class governs tolerances for straightness, flatness, and parallelism. Key Tolerance Categories ISO 13920 standard
According to technical guides from Scribd and Modulus Metal , the permitted deviations for Class B depend on the size of the component: Range of Nominal Size (mm) Linear Tolerance (± mm) Over 30 to 120 Over 120 to 400 Over 400 to 1,000 Over 1,000 to 2,000 en iso 13920-bf
Class B allows for the natural thermal distortion that occurs during welding without requiring expensive post-weld machining or straightening processes. This class governs tolerances for straightness