BS EN ISO 13920:1997

1   Scope This European Standard specifies general tolerances for linear and angular dimensions and for shape and position of welded structures in four tolerance classes, these being based on customary workshop accuracy. The main criterion for the selection of a particular tolerance class should be the functional requirements which are to be met. The applicable tolerances are always those which are stated in the drawing. Instead of specifying individual tolerances the tolerance classes according to this standard may be used. General tolerances for linear and angular dimensions and for shape and position as specified in this standard apply for weldments, welding assemblies and welded structures etc. Special provisions may be necessary for complex structures. The specifications given in this standard are based on the principle of independency as specified in ISO 8015, according to which the dimensional and geometrical tolerances apply independently of each other. Manufacturing documentation in which linear and angular dimensions or indications for shape and position are presented without individually indicated tolerances shall be deemed incomplete if there is no, or inadequate, reference to general tolerances. This does not apply to temporary dimensions.