The design of steel structures within Europe is conducted according to Euro-code 3 specifications. The fabrication and construction of these are subject to quality, execution, and control requirements as outlined in EN 1090-2. For welded connections under static loading, Eurocode 3 refers to the quality level C set out in ISO 5817. However, this specification is not explicitly stated in the background document of Eurocode 3. To address this gap, an experi-mental investigation has been performed on 17 specimens exhibiting different weld imperfections with the objective of evaluating the impact of the weld quality levels defined in ISO 5817 on the load-bearing capacity. The tested specimens are butt-welded connections welded from one side with imperfec-tions such as porosity, lack of penetration, and undercut. Non-destructive tests, including visual testing, 3D scanning, and radiographic testing were employed to identify the location and dimensions of imperfections. Next, stat-ic tests showed that imperfections such as lack of penetration and porosity of quality level D or lower reduced the load-bearing capacity. In contrast, un-dercut at quality level D did not have an impact on the static resistance. Fur-thermore, combinations of several imperfections had a significant impact on the load-bearing capacity. These findings provide valuable insights that may be used to reassess the necessity of quality level C required in EN 1993-1-8 for the static resistance.