This standard specifies quality levels for imperfections in arc-welded joints in aluminium and its alloys. It applies to material thickness above 0,5 mm. It covers full-penetration butt welds and all fillet welds. The principles of this standard may also be applied to partial penetration butt welds. Three quality levels are given in order to permit application for a wide range of welded construction. They are designated by symbols B, C and D. Quality level B corresponds to the highest requirement of the finished weld. The quality levels refer to production quality and not to the fitness for purpose of the product manufactured.