Analysis of creep lifetime of a ASME Grade 91 welded pipe

A multi-material local approach to creep damage was applied to a ferritic-martensitic ASME Grade 91 steel welded joint at 625 °C. Focus was made on the detailed analysis of the most sensitive area of the weld i.e. the intercritical heat affected zone. Prediction of creep failure of the weld well agrees with experimental results. The model was then applied to the case of a seam-welded pipe exhibiting a roof defect, creep tested at 580 °C, showing consistent results with a more classical engineering assessment.