Engineering application of flanged flexible expansion bend

Under the action of ocean current, some submarine pipeline is suspended as the result of seabed scouring, especially in the place near the caisson platform, and it seriously affects the safe operation of in-service submarine pipelines. In similar special environment, it is crucial to select appropriate expansion bend materials for the long-term safe operation of the entire submarine pipeline. Taking the flexible expansion bend installation works in one oilfield in Liaodong as the example, the structural form and basic parameters of the selected flexible expansion bend were introduced, the advantages of the flexible expansion bend over s teel expansion bend were analyzed, and the installation method was studied. The following measures were proposed to solve the three technical difficulties in installing the flexible expansion bend, including using cement sandbags for the scour position and riser suspension treatment to facilitate the support of the flexible expansion bend, setting reasonable bending limit to ensure the consistency of installation route and flexible expansion bend design, and hoisting the flexible expansion bend into the water with horizontal stays, with two temporary lifting points installed on the platform foundation structure so that the expansion bend flange position can be adjusted by chain block to complete the riser flange connection. The above measures have been verified to be effective in engineering practice and are expected to provide references for similar installation projects in the future.