Chapter 8 - Offshore pipeline mechanical design

Abstract

The most important issues related to the mechanical design of offshore pipelines are examined, with reference to two major design specifications: the API 1111 specification and the DNV-ST-F101 standard. The provisions of these two major standards related to mechanical design are presented and their connection with the mechanical behavior of metal rings and pipes, analyzed in previous chapters, is pinpointed, with emphasis on collapse, which is the critical failure mode during the installation process. Combined loading conditions, buckle propagation and buckle arrest are also presented. Pipe collapse is further discussed, presenting some background for the development of API 1111 and DNV-ST-F101 collapse provisions, together with some additional methodologies for predicting pipe collapse. Pipe collapse is also presented from a unified perspective, using the concept of ring slenderness. Finally, the influence of pipe fabrication on collapse pressure is briefly discussed.