Fracture mechanics-based fatigue crack growth prediction methods based on the line spring technique are presented. Developments in the line spring method are described that make it possible to apply the method to realistic welded structures for fatigue design studies. The line spring finite element described in the paper has been formulated to fit between isoparametric brick elements in order to allow shell-to-shell junctions to be represented more accurately. The effect of stress concentrations at weld toes has been also introduced. The accuracy of the line spring approach for the calculation of stress-intensity factors is demonstrated by comparison with three-dimensional finite element fracture mechanics results and empirically estimated values. Prediction of fatigue crack growth in girth welds and tubular connections is compared with observations of cracking in large-scale test specimens. An example of how the fatigue crack growth prediction methods could be applied to the design of welded joints is presented.