ICSID 2019

Dubrovnik, Croatia, June 4 – 7, 2019

Structural integrity assessment of pressure vessels by using the risk based approach

Snežana Kirin, Aleksandar Sedmak
University of Belgrade, Serbia

Risk Based Approach to Life Assessment of Welded Structures has been applied to rig pipes, old and new ones. The new concept based on application of risk matrix to assess risk level according to probability and consequence of failure was used. Rig pipe integrity has been assessed by using the Failure Assessment Diagramme (FAD), i.e. the ratio of linear elastic fracture mechanics parameter, KI, and its critical value, KIc, in relation with the ratio of applied stress and its critical value. Probability of failure is then taken according to the position of the point in the FAD, corresponding to old and new rig pipes data. Rig pipes life has been assessed by simulating fatigue crack growth by the extended Finite Element Method (xFEM) to obtain corresponding number of cycles in each growth step. Probability of failure is then taken as the ratio of the number of cycles for a given crack length and the number of cycles for the critical crack length. These analyses are useful for managers to make decision about further use of damaged pipes, based on data provided by engineers.