Experimental and Analytical Study for the Installation of Flexible Pipe in Existing Submarine Pipelines by Pipe-in-Pipe Technology

摘要

The pipe-in-pipe technology has been developed by the authors for one of the Japanese oil refineries in order to apply the new technology in the renovation project of the existing old submarine pipeline with more than 3 km length. In the project the newly designed flexible pipe, similar to flowlines applied in the subsea projects in the world, is installed in the existing 18 inch submarine pipeline with several bends by pulling the head of the flexible pipe. The flexible pipe can be designed against the appropriate tension expected in the installation by the selection of size and number of wires called as tension members. However, the weight of the flexible pipe might be too heavy if the tension members are wrongly designed. This causes heavier self-weight and at the same time higher friction, which increases the design tension accordingly. In this report the experimental works for the pulling tension of flexible pipes with small-scale and full-scale models are shown first. Then the analytical studies based on a simple beam theory to calculate the pulling tension are presented to simulate the experimental results. Finally, the measured tension in the actual renovation project, which was successfully executed in June 2002 in Japan, and the calculated tension are compared.