HT subsea pipelines are usually buried in the seabed to avoid lateral buckling induced by thermal loads and a certain depth of trench should be also required to assure that no upheaval buckling would occur. Recently, a new safety concept was proposed that moderate pipe buckling is acceptable and even can be utilized to release thermal forces in the pipeline. Issued from such a concept, an anti-buckling technique was developed, which is to induce the pipeline reaching a buckling state by pre-heating before trenched, then to bury the buckles at their pre-heating place. In such a case, tensile force will be induced in the pipeline by environment cooling before the pipeline put into service, so the risk of upheaval buckling can be depressed in succeeding formal service. The fact that Glamis flowlines had successfully avoided upheaval buckling by using hot water flushing technique provides a practical verification for this technique. This paper theoretically analyzes this technique by using FE models, and the results of pipe-soil coupling analysis indicate that under a certain condition 12.95 degree Celsius of thermal load can be abirritated in buried heated pipeline after applying pre-heating before trenched technique.
展开▼
