Modern automation and robotization of production processes requires new and fast methods of product quality control. In the case of arc welding in robotic systems, where the production process takes place in large series, it is important to quickly control the correctness of the weld. Based on visual data, the system should be able to automatically determine whether a given weld meets the basic quality requirements, and thus be able to stop the process in the event of identified defects. The article presents the results of research on the creation of a visual method for assessing the correctness of the weld seam based on the deep neural network classifying, locating and segmenting welding defects. The proposed detection method was extended by using a combination of a vision system camera with a six-axis industrial robot in order to enable detection of a larger number of welding defects and positioning in a six-dimensional workspace. The research results presented in this article were obtained during the implementation of the project entitled „Development of a method based on the use of deep neural networks for visual inspection of welded joints in the course of R&D works” implemented at the company ZAP-Robotyka Sp. z o.o. in Ostrów Wielkopolski.