Recent Development and Validation of the Latest FlawPRO™ ECA Methodology

Abstract

The graphical user interface driven engineering software tool FlawPRO™ has been extensively used for subsea pipeline design and installation under high strain or fatigue intense applications. The methodology included in the program has evolved since its inception in 2002 through a series of JIPs involving major oil and gas operators and installation contractors. This paper summarises the fracture mechanics concepts incorporated in the methodology of the latest version of FlawPRO™ and the results of an extensive full scale flawed pipe testing programme that included over 45 reeling simulations and other fracture tests performed to validate the methodology. It is shown that the program’s crack growth predictions under large strain reeling are consistent with test data obtained from reeled pipes containing centreline flaws in over-matched welds, with the majority of the predicted results obtained using average material property data scattering around the mean 1:1 line consistent with uncertainties in the mechanical property values used in the validation. The results of an assessment of some of the reeling test data using the DNV ECA methodology (DNV-RP-F108) are also presented. It is concluded that the FlawPRO™ methodology is consistently more accurate in assessing the test data compared with the DNV methodology which may yield some non-conservative results. Both methodologies require suitable factors of safety or adjustments to either material and / or load inputs to maintain conservatism in applications to the pipeline projects.