Modal response of free spanning pipelines based on dimensional analysis

Modal response of short pipeline spans on partial elastic foundations

xix List of Abbreviations and Symbols Used xx Acknowledgements xxv Chapter

Integrity and Fracture Response of Offshore Pipelines Subject to Large Plastic Strains

A design equation for evaluation of strain concentration factor in concrete coated X65 pipelines

This chapter presents the limit-state based strength design of pipeline. Structural design has been successfully carried out using limit state design (LSD) with reliability based techniques which provide a consistent treatment of uncertainties for some days. The limit state design of pipeline is a rational design method based on the idea of a limit state. A limit-state is a condition that limits the continued safe operation of a pipeline. It is exceeded when the response of the pipeline to loading is unacceptable. Each limit state divides the pipeline into two states, the safe state and the failed state. In this chapter, four limit states are checked for the pipeline design, including ultimate limit state (ULS), serviceability limit state (SLS), fatigue limit state (FLS) and accidental limit state (ALS).

Limit-State Based Strength Design

This paper concerns the strain distribution, and in particular strain concentration in field joints, for concrete-covered pipelines during laying. A semi-analytical model, full-scale tests to verify the model, and results of a parameter study are described. The model is used to establish nonlinear moment-curvature curves at a number of cross sections on the concrete-coated pipe and in the field joint (FJ). These are used to establish a strain concentration factor (SCF) for the FJ, or characteristics for a varying stiffness model of a pipe for direct use in lay analyses. Constant moment, four-point bending tests have been conducted on 16-in and 20-in dia, concrete-coated pipes as well as material tests on the pipe steel, corrosion coating and concrete. The behavior of the pipe, and in particular the SCF at the field joints, is investigated and compared to predictions using the semi-analytical model. The model is found to give a good prediction of the SCF and strain distribution along the pipe joint, for both the steel and the concrete, and is suitable for use in lay analyses for the overbend of S-mode lay vessels.

O. B. Ness

Papers

Strain concentrations in pipelines with concrete coating