Creep constraint analysis and constraint parameter solutions for circumferential surface cracks in pressurized pipes

Creep crack-tip constraints for inner circumferential surface cracks in pressurized pipes have been analyzed by three-dimensional finite element method and the constraint parameter R∗ solutions have been obtained for different pipe geometries and crack sizes. It has been shown that the constraint level of circumferential cracks is lower than that of axial cracks, and the constraint effects need to be considered in creep life assessments of pressurized pipes. The benefits from incorporating constraint effects are greater for the circumferential cracks than for the axial cracks and for the shallower and shorter cracks than for the deeper and longer cracks.