sealant being introduced via the right hand end of body 26 then tube 20 with its connected nut 28 is moved toward reducing union body 26 at this point if desired tube 20 can first be moved to a position where its left hand end is a short distance from reducing union body 26 and sealant material can be injected into the left hand end of tube 20 preferably until sealant material can be seen through potting hole 22 thereafter flexible tube 20 is inserted into reducing union body 26 and the associated nut 28 is tightened thereon to establish the assembled relation illustrated in the figure at this point the remainder of the interior of flexible tube 20 is filled with potting material 30 injected via potting hole 22 after which nuts 28 can be fully tightened to establish the desired sealing and insulating properties the sealant material described above must be cured for a period of the order of seven days or longer if a different type of sealant material is used a different curing time appropriate to that material will be employed subsequent to curing shrink tubing 32 is slipped over flexible tube 20 to the position illustrated in the figure and then heated to shrink it to the final configuration illustrated in the arrangement shown in the figure the length of flexible tube 20 is sufficient to allow the right hand end thereof to enclose the left hand end of sheath 4 if flexible tube 20.