Page 90 - Pipelines and Risers
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Chapter 4
Limit-state based Strength Design
4.1 Introduction
This chapter presents limit-state strength criteria for pipeline design.
The limit-state based strength design became crucially important when usage factors in wall-
thickness design are raised from those given by traditional design codes.
The discussion of a limit state design approach in this chapter is based on new GuidesRules
and a review of recent design projects and Joint Industry Projects (SUPERB, DEEPPE, etc.).
See Bai and Damsleth (1997).
The limit state checks conducted in the strength design are:
0 Out of roundness for serviceability
0 Bursting due to internal pressure, longitudinal force and bending
Buckling/colIapse due to pressure, longitudinal force and bending
Fracture of welds due to bendingltension
Low-cycle fatigue due to shutdowns
Ratcheting due to reeling and shutdowns
Accumulated plastic strain
The allowable strains, equivalent stresses and bending moments are determined for the
following operating scenarios.
Empty condition
Operational conditions
