Abstract
This paper describes several recent advances in crack assessment technology that have been or will be incorporated into the API 579 fitness-for-service standard. Four technology areas are addressed herein:
• Stress intensity factor solutions. The 2016 edition of API 579 contains an extensive library of stress intensity solutions inferred from 3D finite element analysis.
• A new equation for fitting elastic-plastic J solutions. A parametric equation that captures the elastic, fully-plastic and contained-yielding regimes of deformation provides an alternative definition of reference stress in the failure assessment diagram (FAD) method.
• An enhanced constraint adjustment. A future edition of API 579 will include an improved version of the Wallin methodology for shifting the Master Curve reference temperature to account for constraint effects.
• A procedure to account for non-ideal crack profiles. Most crack assessment methods assume an idealized flaw shape such as semi-elliptical, but many real-world flaws have complex shapes.
