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    Sonsub patent for replacing pipelines

    News // August 24, 2001
    Sonsub in Houston has announced that it has been awarded a patent for a method and apparatus for replacing damaged sections of a subsea pipeline without loss of product or entry of seawater into undamaged portions of the pipeline.

    The method comprises the installation of a pair of specially designed hot tap tees on either side of the damaged section of pipeline and then cutting a hole at an angle in the pipeline through each hot tap tee.

    Specially designed plugging pigs are then inserted through the tees and secured inside the pipeline. The damaged section of pipeline, along with the hot tap tees, can then be cut out and replaced with a new section of pipeline without loss of product tothe seawater environment.

    The specially designed plugging pigs utilised in this method include cup seals to plug the pipeline and cam operated slips to hold the pig in position. After the pipeline has been repaired, a control system incorporated in the pig releases the slips in response to pipeline pressure.

    After the slips are released, the pigs travel in normal pigging fashion and are then removed from the pipeline.

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