reciprocal of the angle of the inclined surface 24 of the members 20 the wedge member 50 is provided with a plurality of gas passageways 56 and an annular stepped recess 58 an annular cover 60 is adapted to fit within the stepped recess 58 to form a gas manifold the unthreaded portion of the shaft 40 terminates in a coupling 64 adapted to communicate with a remote source of purge gas the coupling 64 is provided with a wrench receiving portion 65 which may be employed during the assembly of the tool 10 into and out of operative position the purge gas communicates with the manifold 62 through a central bore 66 which terminates in radially outwardly extending passageways 68 in the assembled form of the invention as illustrated in fig2 and 3 it will be noted that the gripping members 20 are disposed in an annular array about the center shaft 40 the inclined surfaces 24 and 26 of the members 20 are urged into contact with lands 48 and 54 of the spaced apart wedges 44 and 50 respectively by tension springs 70 and 72 disposed within the grooves 32 and 34 respectively in operation the tool 10 is initially adjusted by suitable spacing of the wedge members 44 and 50 to cause the outermost surfaces 28 of the gripping members 20 to assume a configuration of size permitting insertion into the interior of pipes 12 and 14 the.