Floating pipelines are either formed of steel pipes supported at regular intervals by buoyancy units or surrounded by a buoyant case, or they are composed of pipes made of a buoyant material.
In all these cases the pipeline must be built to be flexible enough to endure the movement of the sea and currents. The pipe itself may be made flexible by inserting ball joints in the line at regular intervals or by adding lengths of flexible pressure hose. All floating pipelines are made in a modular fashion and are connected together by bolts or quick coupling devices.
Submerged or sinker pipelines
Submerged pipelines are made by welding a number of pipes together into a long string. They are floated into place, full of air and then sunk in the desired location (thus ‘sinkers’) by flooding the pipe. At each end of the pipeline, flanged connections or ball-joints are provided to enable the submerged lines to be connected to the floating or landlines.
Land or shore lines
Land or shore lines are relatively short lengths of standard pipe, bolted together laying onshore. Various devices are incorporated in the land pipeline so it can be moved or extended or to switch the flow to different sections of the discharge area. The line may also be equipped with manual or hydraulically operated valves, Y-pieces and bends of different angles.
All pipelines need to be turned regularly during use, to ensure that wear is even and hence pipeline life is maximised.