The API recommended practice for fixed offshore platform design has for many years provided guidance on fatigue design of welded connections in offshore structures. As this practice, designated API RP 2A is transformed into an international ISO document, the fatigue provisions, as well as many others are being re-evaluated. In light of the research on fatigue of welded connections and the different provisions of many European design practices, major changes can be expected from the current ones in API RP 2A. Areas covered include the choice of stress concentration factor; the appropriate design lines for fatigue; and changes to those design lines due to thickness, weld profile, and post-weld improvement. Each of these provisions can be expected to be modified from the current document as the ISO version is promulgated.
The API recommended practice for fixed offshore platform design has for many years provided guidance on fatigue design of welded connections in offshore structures. As this practice, designated API RP 2A (API 1993), is transformed into an international ISO document, the fatigue provisions, as well as many others are being reevaluated. In light of the research on fatigue of welded connections and the different provisions of many national design practices, major changes can be expected from the current ones in API RP 2A. This paper will discuss the choice of stress concentration factor; the appropriate design lines for fatigue; and changes to those design lines due to thickness, weld profile, and post-weld improvement. Provisions in each of these areas can be expected to be modified from the current document as the ISO version is promulgated. The focus of the paper will be on simple, un-reinforced tubular joints, although some of the information will certainly apply to other cases.
