US Patent 7628176 Pipeline stop

A pipeline stop is used to temporarily plug a pipeline to allow repairs to the pipeline. The pipeline stop includes lateral sections expanded into a sealing position blocking flow through the pipeline. A central section is moved downwardly to expand the lateral sections. Inclined links transfer force from the central section to the lateral sections. As the central section moves downwardly, the links move from a first inclined position to a second, more nearly horizontal, position. Upward movement of the central section allows the lateral sections to retract, typically by use of springs.