In order to avoid any confusion, the types of imperfection are defined with explanations and illustrations where necessary ISO consists of the following parts, under the general title Welding and allied processes — Classification of geometric imperfections in metallic materials: PartFusion welding — PartWelding with pressure Annex A of this part of ISO is for information only ILNAS-EN ISO Welding and allied processesClassification of geometric imperfections in metallic materialsPartFusion weldin