The keyword refers to a specific tolerance class within the German industrial standard DIN 8570 , which outlines general tolerances for welded structures . While this standard was officially superseded in 1996 by the international standard ISO 13920 , it remains widely cited in legacy engineering drawings and technical documentation across the globe. Understanding DIN 8570
: Medium (the most common standard for general engineering). Class C : Coarse. Class D : Very Coarse. Linear Dimension Tolerances for Class B din 8570 b pdf
For Class B, the permissible deviations depend on the nominal length of the welded component. According to available technical tables from DIN 8570 , the limit deviations in millimeters for Class B include: : ±1plus or minus 1 Over 120 to 400 mm : ±2plus or minus 2 Over 1000 to 2000 mm : ±4plus or minus 4 Over 4000 to 8000 mm : ±8plus or minus 8 Transition to ISO 13920 The keyword refers to a specific tolerance class