# A Case Study of Floating Offshore Super-Long Steel Pipeline Combing with Field Monitoring
## 6 Conclusions  
Considering that the floating process of super-long steel pipeline at sea is a nonlinear geometric large deformation problem and is very sensitive to the load. This paper conducts field monitoring and dynamic construction of the super-long steel pipeline offshore floating project to feedback the deformation state of the pipeline to the construction institution, enabling construction institutions to adjust construction operations. Strictly control the deformation of the pipeline to ensure the safety of the extra-long steel pipeline floating, and obtain valuably measured and analyzed data, which provides a reference for similar projects. The specific conclusions are as follows:  
* In the process of floating transportation, the pipeline was under the stress state of the upstream and the downstream, and the strain of the upstream and the downstream was obviously greater than that of the top of the steel pipeline. The strain at the bend was larger than that at the straight section. The long-distance pipeline could also maintain good consistency in its stress state while floating. Therefore, in the process of construction and monitoring, special attention should be paid to the upstream, downstream and bend of the floating steel pipeline, to keep the force on the pipeline uniform.
* If other structures (such as tugboats) were not added, the vibration frequency of the pipeline would remain basically unchanged. The amplitude would increase with the increase of wind, wave and water flow, and decrease obviously with the increase of the number of tugboats. The number, position and speed of tugboats both affected the pipeline, so the tugboats must be adjusted reasonably in the construction operation.
* The offshore floating transport pipeline should be subjected to on-site strain and modal monitoring at the same time. The monitoring personnel should feedback the data to the construction institution in real-time, giving a warning when necessary, and use the monitoring data to guide the construction institution to adjust the construction plan reasonably and dynamically. To ensure the strain and anticorrosion coating of the steel pipeline are within a safe range during the floating transportation and prevent the vibration damage of the pipeline. If it is possible, distributed optical fiber sensors can also be used for full-length and overall non-destructive monitoring of the kilometer pipeline, its event recognition and positioning capability are more accurate and early warning will be more accurate and timely.  
Conceptualization, J.Y.; Data curation, C.R., J.C. and W.C.; Formal analysis, Y.C.; Funding acquisition, J.Y.; Investigation, J.Y. and Y.W.; Methodology, C.R.; Supervision, Y.W.; Validation, Y.W.; Visualization, Y.C.; Writing--original draft, J.Y.; Writing--review & editing, C.R. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the National Natural Science Foundation of China under Grant 51874144, Grant 51978292, and Grant 42077254, in part by the Scientific and Technology Plan Projects in Xiamen, China under Grant 3502Z20193040, in part by the Subsidized Project for Postgraduates' Innovative Fund in Scientific Research of Huaqiao University under Grant 18014086003 and Grant 18013086018.  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** This work was supported by the National Natural Science Foundation of China (51874144, 5197829 and 42077254); Scientific and Technology Plan Projects in Xiamen, China (3502Z20193040); and Subsidized Project for Postgraduates' Innovative Fund in Scientific Research of Huaqiao University (18014086003 and 18013086018).  
**Conflicts of Interest:** The authors have declared that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work.