Trade-off curves provide a simple visual representation of the performance limits possible within a given design. They usually characterize the relationship between two or more key parameters that link design decisions to factors of importance to customers, such as the relationship between pipe wall diameter and thickness (design decisions) on the one hand and fluid pressure and velocity (customer requirements) on the other.
To a trade-off curve belong a picture of the component and/or process, a description of the failure mode (failure mode), an analysis of the cause, possible countermeasures, a graph showing under which conditions the failure mode occurs and a description of the relations between the most important parameters (see illustration page 113). On this basis, design groups create a so-called engineering check sheet on which the main points of the investigation of the trade-off curve are summarized in a compact and efficient way. That summary is used in design reviews.