Pipe plugging tool

Claim 1

An expandable pipe plugging tool for plugging off fluid flow through a pipe upstream of a valve, the pipe plugging tool comprising a pipe section having one open end, the opposite end thereof being closed, a drain valve providing communication between the inside of the pipe section and the outside of the pipe section, a coupling attached to the open end of the pipe section providing for attachment of the pipe section to the valve, said pipe section having a centrally disposed aperture in the closed end thereof, an elongated hollow tool rod slidably disposed within the aperture, sealing means interposed between the aperture and the tool rod, at least one alignment bushing secured within the pipe section adjacent to the closed end thereof, said tool rod being in sliding engagement with the bushing for Alignment of said tool rod with respect to the pipe section and for the prevention of angular pressure being applied to said sealing means, an expandable cylindrical plug of resilient material secured to one end of the tool rod and slidably disposed within the pipe section, said plug having a plurality of spaced annular grooves around the outer periphery thereof and a longitudinal centrally disposed bore therethrough, and an operator means operably connected between the expandable plug and the opposite end of the tool for selective radial expansion and contraction of the plug, said operator means including an elongated operator rod slidably disposed within the tool rod and the expandable plug bore, a first disc-shaped retainer plate rigidly secured to one end of the operator rod for retaining the plug thereon, a second disc-shaped retainer plate having a centrally disposed aperture therein, said second retainer plate being slidably disposed on the operator rod between the opposite end of the plug and one end of the tool rod, a seal interposed between the tool rod and the operator rod to prevent passage of fluid therebetween, and a take-up operably connected to the operator rod on the end opposite the expandable plug which provides for reciprocal motion of the operator rod within the tool rod and within the takeup, said take-up comprising an elongated cylindrically shaped take-up nut having a centrally disposed threaded bore therethrough, a thrust washer, and a plurality of corresponding threads on the end portion of the operator rod on the end opposite the expandable plug, said end portion of the operator rod being threadedly journalled within the take-up nut with the thrust washer being disposed about the operator rod and interposed between the take-up nut and the end of the tool rod; whereby, upon rotation of the take-up nut in one direction relative to the operator rod, the end of the operator rod opposite the take-up nut will be moved in a longitudinal direction away from the thrust washer, and upon rotation of the take-up nut in the opposite direction relative to the operator rod, the end of the operator rod opposite the takeup nut will be moved in a longitudinal direction toward the thrust washer; and whereby the coupling may be attached to the valve, the expandable plug passed through the valve into the pipe upstream of the valve, the operator rod retracted within the take-up to move the first disc-shaped retainer plate closer to the second disc-shaped retainer plate and thereby longitudinally compress the expandable plug to effectuate an expansion in the diameter of the outer periphery of the expandable plug to close off the pipe upstream of the valve, and the drain valve opened to bleed pressure from the valve and to determine the completeness of the seal of the expandable plug in the upstream pipe, thereby permitting the removal of the pipe section and the valve while leaving the expandable plug and the tool rod in place to facilitate maintenance or replacement of the valve with substantially no fluid loss.