Method and apparatus for injecting foam into a pipeline, including an inflatable plug

Claim 1

A unitary molded rubber plug for use in injecting foam into a pipe via a foam-conducting flexible tube, comprising: a flexible-walled, constant-diameter, smooth-surfaced, imperforate through-conduit for passage of said tube therethrough, a flexible imperforate cylindrical outer wall surrounding and spaced from said through-conduit by a chamber, and a pair of stiff, thick annular end walls integral with said outer wall and with said through-conduit and thicker and stiffer than said outer wall and through-conduit, so that no additional members are required to retain them against expansion when said plug is inflated for use, said end walls defining the ends of said chamber and joining said outer wall to said through-conduit, one said end wall having air inlet means for said chamber, said plug being normally slidable relative to a said tube when said plug is inflated sufficiently to engage immovably against a said pipe, so that said tube can extend through and beyond said plug to a desired location and can be moved relatively to said plug, said through-conduit holding a said tube snugly when said plug is further inflated, said outer wall then engaging and sealing against said pipe.