Mechanical analysis and design of ocean flexible pipes

Dr. Jun Yan, Lecturer , Department of Engineering Mechanics, and State Key Lab of Structural Analysis of Industrial Equipment, Dalian University of Technology, Dalian, 116024, P. R.China. E-mail:

Pipelines are widely used in oil and gas industry not only on land but also offshores. Normally, the pipelines are made by steel, but in many cases the steel pipe could not resist large deformation exerted by severe environmental forms. Recently flexible pipelines made by composite material are extensively used for a variety of applications in the ocean petroleum industry due to many merits, such as the excellent properties in flexibility, corrosion resistance, thermal insulating simple laying method, and building block design, etc.

In recent years, oil exploitations have reached deep water areas, which need pipelines be not only more flexible but also strong enough. There is a need to develop a rational design method for the flexible pipe.

In order to make conception design, we need to know its basic mechanical behavior and the typical failure modes of the flexible pipes in laying and working conditions.

In 2007, a research group for flexible pipes was set up in Dalian University of Technology. The essential objective of this group is to investigate the mechanical behaviors and design the ocean flexible pipes properly based on the laboratory tests and numerical simulations. Then some useful advices on the rationality, economical efficiency, reliability and durability for design and application of existing flexible patterns can be proposed. Moreover, a further target is to demonstrate the feasibility in deep-sea application and develop its corresponding design criteria in some extreme serving conditions of flexible pipes.

In 2009 REU program, the student will investigate mechanical behavior of flexible pipes by analytical and FE methods, and then rationally design flexible pipe under actual static loads.

Tasks:

(1)  Learn basic knowledge of Flexible pipes, such as composition, application and failure modes.

(2)  Simplify global analysis model under laying and working load case, such as tension, pressure, bending and torsion.

(3)  Based on theoretical analysis and simplified analytical model, establish the geometric and physical models on ANSYS. Compare the simulation results with the laboratory tests data and validate the numerical model.

(4)  Carry out the numerical tests under classic/extreme loads based on (2). Change the parameters of the pipe, such as layers, angle, thickness, etc. Reveal the distribution of the force and transmission mechanism between the layers. At last rationally design flexible pipe.

(5) 

References

1. Feret, JJ and Bournazel, CL (1987).Calculation of Stresses and Slip in Structural Layers of Unbonded Flexible Pipes, Journal of Offshore Mechanics and Artic Engineering, No 109, pp 263-269.

2. Witz, JA (1996). A Case Study in the Cross-section Analysis of Flexible Risers, Marine Structures, pp. 885-904.

3. Ramos, R, Pesce, CP (2002). A Consistent Analytical Model to Predict the Structural Behavior of Flexible Risers Subjected to Combined Loads, Proceedings of the 21st OMAE, No 28081, Oslo.

4. Elton J. B. Ribeiro(2003), On the Tension-Compression Behaviour of Flexible Risers, Proceedings of The Thirteenth ISOPE,pp105-112

5. Y Zhang, B Chen, L Qiu, T Hill, M Case Halliburton Wellstream. State of the art analytical tools improve optimization of unbonded flexible pipes for deepwater environments, Offshore technology Conference, OTC 15169, Houston, Texas, U.S.A.,5–8 May 2003.