Correlation of creep crack-tip constraint between axially cracked pipelines and test specimens

In this paper, based on the creep constraint parameter R, the creep crack-tip constraints in axially cracked pipelines and various test specimens have been analyzed under conditions of plane strain and steady-state creep, and correlation of the constraint between the cracked pipes and test specimens has been investigated. The creep crack-tip constraint of the single-edge notched tension (SENT) specimen is close to that of axially cracked pipes. The pin-loaded SENT specimen (SENTp) with a/W = 0.35 and 0.05 W loading point offset provides a closely matched creep crack-tip constraint with the axially cracked pipes. It will be more accurate if the creep crack growth rate and creep fracture toughness data measured by the SENTp specimen are used in integrity assessment of axially cracked pipes. The results provide a strong support for use of constraint-designed specimens in creep failure assessments of pressurized pipes at high temperature.

► Correlation of creep constraint between pipes and test specimens is investigated.
► Pin-loaded SENT specimen provides a closely matched creep constraint with pipes.
► It will be accurate if the SENT specimen data are used in assessment of pipes.
► Results provide a strong support for use of creep constraint-designed specimens.