This paper presents the quality control procedures used in manufacturing process of the components of a particular butterfly valve. Quality control procedures refer to non-destructive material testing methods and heat treatment specified by the Inspection and test plan (ITP). In the theoretical part of the paper, the general and physical foundations are described in more detail, as well as the way of implementing individual methods. The heat treatment procedures are listed with the annealing treatment, characteristic for the production of welded type parts, is described in more detail. In the experimental part of the paper, following the technological process of manufacturing, the application of non-destructive methods during a certain phase of the manufacturing process of an individual component is shown. Control of the heat treatment process of annealing was carried out. The following documentation is presented as proof of the correctly implemented component production phase, which is essential for functionality and safe operation. Title: In-process quality control of butterfly valve manufacturing.