Quelle est la meilleure façon d’optimiser la conception structurelle des pipelines sous-marins ?

To optimize structural design of pipeline in term of material can be done selecting the most optimum strength to cost criteria. The load cases considered shall be full life cycle of the pipeline, starting from fabrication, transportation, installation and operation. It shall also consider reliability and integrity, which is commonly having linear correlation to the technology readiness level.

The best approach to optimize the structural design of underwater pipelines involves thorough analysis and consideration of various factors such as water depth, seabed conditions, environmental loads, and material selection. Utilizing advanced computational tools and conducting comprehensive simulations can help engineers assess stress distribution, fatigue, and corrosion potential. Additionally, incorporating robust anchoring and support systems, along with regular maintenance plans, ensures the longevity and reliability of underwater pipelines.

The pipeline route should also take into account the bathymetry of the seabed because large slope variations will likely cause free spans that could potentially present VIV issues. And of course project economics is the major driver of any subsea layout. The pipeline engineer designing the pipeline route should always try to minimize the route length and number of crossings within the bounds imposed by the project at hand.

Most optimization in structural design is done by either more advance engineering method or based on qualification. But before that can be done, all the failure modes shall be detailed identified. By knowing each respective failure mode, the extra allowances provided due to allowable stress design or prescriptive design process can be reduced to be fit for purpose, or qualification can can be done according to performance based design.

FEA of underwater pipelines is a complex subject. The elastoplastic regime of the material shall be accounted for, as well as geometric nonlinearity. The pipe-soil interaction is nonlinear and there may be berm formation. The environmental loading has a stochastic nature, hence extreme conditions shall be accounted for. In addition, many of the loads to which underwater pipelines are subjected to have a cyclical nature (e.g., operational shutdowns, VIV, etc.) that may induce material fatigue. A good underwater pipeline design will address all the potential failure modes in dedicated FEA models to guarantee that the integrity will not be jeopardized throughout the entire lifetime of the system.

Testing and inspection explained above is after installation, nothing to do with structural design optimization. When we are talking about design optimization, it must be testing for qualification. Performance based design where the design is based on certain performance criteria validated by testing data.

The only way to be entirely sure a design is robust is to relate it to the actual physical performance of the installation. Review and revision of standards and regulations is then possible armed with practical evidence.

Before starting with FEA we need to obtain the inputs. Metaocean data, geophysical and geotechnical surveys, seismic evaluation and seismic engineering (if deemed require), flow assurance analysis for pressure/temperature data, and reservoir data. Each is a mini project of its on, and that’s just the beginning.

We shall differentiate terminology between code, standard, specification, guideline and recommended practice. The applicability of each term is different, between mandatory or not, whether it will have legal implication if it is not complied.

When it comes to subsea pipelines, the most widely adopted standards are DNV-ST-F101, API 1111 and ASME B31. API 17B and API 17J are recommended practices that should also be mentioned regarding flexible pipelines. In addition, there are also many complementary recommended practices, which are usually referenced within the aforementioned standards to address specific topics.

Innovation in this context should refer to new technology, be it material, design concept or even just new way of performing the design. However utilization of new technology comes with risk in term of failure mode uncertainty, therefore staged gate development is required to reduce the risk while balancing the cost and resources to perform qualification and testing to mature the technology, mitigating the failure mode and to reduce the risk to as lo as reasonably practicable (ALARP).

1. To ensured the truth of design input data i.e. fluid properties of the containment, process flow assurance, corrosion study report, metocean data, geophysical and geotechnical data. 2. Ensure the method of the design and the design process to follow proven quality check and audit as per proven standard. 3. Ensure design phase from conceptual until detail engineering work to be properly performed, without any carry over scope in between the design phase. 4. Ensure all proven design code and standard have been applied. i.e. ASME, API, AGA, DNV, ISO, etc 5. Ensure all phases of the design tobe performed by experiences and competent body. 6. Ensure the bidding process for selecting the consultant be performed without hanky panky