On the assessment of non‐conformities. Is execution of steel structures a craft with zero defect tolerance?

Is a non‐conformity in the weld seam of a bridge a reason to refuse acceptance or even a safety risk? Behind this lies the controversially discussed question of whether non‐conformities to the technical design standards, e.g. the evaluation groups according to DIN EN ISO 5817, constitute “acceptance criteria” or “quality guidelines” for steel construction. Often the economic success of a project depends on the answer to this question. Nevertheless, there is currently no uniform procedure on how to deal with deviations and which methods are permitted in addition to reworking or rejecting components to prove usability. This regulatory gap is unsatisfactory for all project participants and the subject of many legal disputes. Particularly due to the simplified applicability and the increasing sensitivity of non‐destructive testing methods and the associated partly detective checks of steel structures, irregularities are detected that no longer reflect the original quality‐assuring idea of non‐destructive testing. The actual component function thereby recedes into the background and the question arises as to whether one can or even must demand zero‐defect tolerance from steel construction as a craft. In our article we go into the background of these questions and give recommendations for action based on our project experience, which should help to carry out even large and complex projects to everyone's satisfaction. Using individual examples, we show the connection between design rules and execution standards and explain the possibilities in the evaluation of detected non‐conformities.