Stop changer tool for in-service valve

Abstract From the Canadian patent

Abstract of the Disclosure, A stop changer tool for removal of an in-service valve under pressure and comprised of a displaceable shaft assembly supporting at one end an axially compressible elastomeric plug adapted to be inserted through the valve into the upstream pipe. The plug is mounted between a pair of restraining ends such that displacing the shaft assembly in a withdrawal direction draws the restraining ends toward each other to compress and diametrically enlarge the plug until a pressure sealing engagement is achieved with the pipe surface thereat. The restraining ends are formed of laterally displaceable contiguous elements having predetermined face angles on opposing surfaces …