This paper investigated creep crack growth in X20CrMoV 12 1 steel weld joints. Crack growth tests were carried out at 545°C on side-grooved 1/2T CT specimens under static loads. A material with simulated intercritical HAZ properties, along which creep crack growth normally occurs, was produced for this study. Constitutive properties were obtained for the simulated HAZ material as well as for the base metal and weld metal. Finite element analyses of crack growth were performed on the models with and without a HAZ layer, using the experimental crack length-time history. The inclusion of a HAZ layer increased the load line velocities significantly. The crack growth rates were correlated reasonably well with C*(t). The minimum crack extension for validity of C*(t) was found much smaller than the ASTM minimum size, 0.5 mm, for IT CT specimens of creep-ductile materials.