A new procedure is described for the engineering design of fracture-safe steel structures representing weldments, forgings, castings and combinations of these. The procedure is applicable to all steels which have distinct transition temperature features, i.e., excepting the ultra-high strength types which have poorly defined, low-slope Charpy V transition curves. The new procedure is based on the concept of the fracture analysis diagram, which represents a consolidation of the available knowledge concerning flaw size, stress and temperature requirements for the initiation and propagation of brittle fractures. The bases for the development of the diagram are explained. Extensive failure and structural test data are provided as documentation of the validity of the described procedures. The practical engineering use of the fracture analysis diagram is based on the determination of a simple parameter - the NDT temperature of the steel. All other required information involves elements which are normal considerations in design of engineering structures.