Quality assurance systems in welding engineering demand that the manufacturers of welded structures and welding equipment should apply qualified welding technologies. The most commonly used mode of welding technology qualification is testing a given welding technology by making test joints and carrying out their examination. This article presents the analysis of test joint dimensions recommended in PN-EN ISO 15614-1 in relation to the possibility of testing the quality of such joints using ultrasonic testing according to recommendations of currently valid related standards. The article contains a proposal how to determine the width of a test joint on the basis of the nomogram developed. The target readers of the article include welding engineers and technologists, other welding coordination personnel involved in the preparation of test joints as well as NDT personnel, due to the extensive analysis concerning the selection of testing methods and ultrasonic examination of test joints.