This paper describes some preliminary results of FE analyses performed to investigate a characteristic creep failure which occurs in a Grade P91 pipe weld, subjected to internal pressure only. The results are related to steady-state creep, using a four-material model. Published and assumed material properties used in the analyses are related to P91 welds at 600degreesC. The peak rupture stresses, in each material zone, for different weld cases, were obtained. The effects of material properties and the width of the low temperature HAZ (Type IV zone), on the peak rupture stress, were identified. The results show that the width of the Type IV zone has an insignificant effect on the peak stresses. For the particular three sets of material properties used in the analyses, it was found that short failure lives are, in general, related to the weld metal properties, and result in failure in the low temperature HAZ over the full range of the tri-axial stress state parameter.