Lateral Buckling Analysis and ECA for Pipeline With Complex Temperature Profile

Abstract

Lateral buckling analysis of a 32 inch export pipeline operating under high temperature and high pressure in sour service environment was evaluated in this paper. In addition Engineering Critical Assessment (ECA) as per DNV-OS-F101 Appendix A was performed to derive flaw acceptance criteria for pipeline girth weld fabrication during installation. Due to the sour operating environment, low fracture toughness and increased fatigue crack growth rate during operation is expected. Consequently stringent tolerable flaw sizes are obtained for the pipeline sections subject to large strain arising from lateral buckling. In order to improve the reliability of the design and constructability of the pipeline, sleepers will be used to introduce vertical imperfections and initiate buckles at selected locations. In undertaking this it can be illustrated that all the potential lateral buckles are predetermined and pipeline sections with large strains are identified. The stringent tolerable flaw criteria from ECA are applied only on the identified high strain sections. In this paper the design of sleepers and the influence of these additional sleepers on the lateral buckling behavior are investigated.