Abstract: A reactor stud hole plug unit having a mandrel with a central stem having a threaded upper portion, a longitudinal passageway extending therethrough and a mandrel plate attached to the lower end. The mandrel plate has threads on its periphery which engage internal threads on a stud hole in a nuclear reactor, and an annular stop is located at the upper end of the threads on the mandrel plate which engages a shoulder on the cavity when the mandrel plate is in position in a stud hole. A compression plate with a central opening having a diameter slightly larger than the diameter of the upper portion of the mandrel stem fits over the mandrel stem, and an annular sealing ring is positioned around the periphery of the mandrel plate above the annular shoulder and in contact with the compression plate when the compression plate is positioned over the mandrel stem.

Abstract: A high pressure pipe stopper includes an elongated stem having a threaded section and terminating at a first end in a conically shaped mandrel having an exterior surface sloped at an angle of about 5.degree.. The pipe stopper also includes a plurality of grip segments about the stem and a nut engaged with the threaded section to force the grip segments up along the mandrel. The pipe stopper may also include an extractor coupling connected between the nut and grip segments such that the grip segments are drawn down the mandrel when the nut is turned away from the mandrel.

Abstract: A high pressure pipe tester plug for insertion into a pipe having a joint such as a weld to be tested includes a stem terminating in a fixed tapered washer, a plurality of grip segments arranged about the stem, an annular floating mandrel positioned about the stem and having an upper retaining section, a cylindrical section and a tapered entry section, an O-ring positioned in an internal recess of the floating mandrel and a ring-shaped seal, rectangular in cross section, positioned about the cylindrical section of the floating mandrel and retained by the upper retaining section. When tightened by a nut, the floating mandrel is forced into the top end of the grip segments, the washer is forced into the bottom end of the grip segments and the ring-shaped seal engages the pipe interior to isolate the joint to be tested.

Abstract: The reactor stud hole plug unit comprises a compression plate, a mandrel, an elastomeric seal ring adapted to be compressed during movement of the mandrel relative to the compression plate and a nut threaded to the mandrel to hold the unit in assembled relationship. The compression plate includes an annular rim spaced inward of the peripheral edge. The compression plate rests on the reactor wall surrounding the hole to be plugged with the rim extending into the hole. The mandrel which has a centrally threaded stud extending through the compression plate includes an upper cylindrical section and a lower cylindrical section of larger cross section with the two cylindrical sections being joined by a frustoconical section. The seal ring which has a rectangular cross section is dimensioned to snugly fit about the cylindrical upper section of the mandrel and to engage the compression plate rim in aligned relationship.