In recent years, there have been some significant technological advances in the field of tubular joints. Many of these advances are reflected in offshore guidance documents, and many more research initiatives currently underway are likely to have a significant impact on design practices. This paper reflects on the current status of tubular joints technology, and examines some of the priority issues which have recently received, and continue to receive, significant research and development attention by the tubular joints community. Both the ultimate limit state and the fatigue limit state are addressed in this paper, and a number of areas are identified where future research should be directed.
Most offshore installations comprise three-dimensional steel frames formed with cylindrical steel members. The cylindrical members provide the best compromise in satisfying the requirements of low drag coefficient, high buoyancy, high strength-to-weight ratio and equal bending strength in all directions. The space inside the hollow sections is often used for transportation, storage or to obtain additional strength. Since the onset of major offshore developments, now more than three decades ago, considerable research has been directed towards the design, construction and performance evaluation of support structures for oil and gas drilling and production operations. For tubular joints, which are formed by welding the contoured end of one tubular onto the undisturbed outside of the other, this research has consumed substantial resources; it is estimated that the financial resources in this respect has exceeded £20 million. The geometric notation for tubular joints is shown in Figure 1. A number of codes and guidance documents provide recommendations which relate to the design, construction and inspection of tubular joints. These recommendations have been derived from an interpretation of research results and in-service performance experience.
