Subsea Pipeline Repair Technology

Recently more and more subsea pipeline accidents have occurred for the reason of corrosion, anchoring, ocean disaster and other human activities. According to different damage to the pipeline and different depth of the location, subsea repair methods and above water repair methods can be used to repair the pipeline. Above water repair of subsea pipeline with davit lifting can be adopted in subsea pipeline installation projects, and this method has been used successfully in many subsea pipeline repair projects. Through analysis of the lifting and lowering operation with related software, such as BCT-35 or SUSPEND program, above water repair of subsea pipeline can be done. On the basis of the calculation results, the damaged pipeline was lifted above the water, then the flanges will be welded by diver at both the pipeline ends. In the year 2008, a piece of 12 inch subsea pipeline was damaged by anchoring in BoHai bay, which was a typical accident and the pipeline was broken and had to be shut down. Compared with subsea wet repair methods, the above water repair method was used. This method has been proved feasible in the year 2008 during BX subsea pipeline repair project. In this paper, the operation procedure of lifting subsea pipeline repair and calculation program been discussed in detail.