Patent Number: 047643323
Section: summary

BACKGROUND OF THE INVENTION The hydrotesting of pipes or tubular elements, such as those found in a nuclear reactor, is often a time consuming operation and suitable sealing elements are not readily available, especially for plain end pipes without threads. In hydrotesting threaded pipes, it is, of course, possible to thread a cap on to the end of the pipe to seal the same and then subject the pipe to pressurized water. In testing of plain end pipes, however, suitable sealing elements are not available. While one type of sealing element for a plain end pipe uses a rubber expandable plug, that is inserted into the pipe to seal the same upon expansion, such as existing device does not withstand hydrotesting at high pressures, such as about 3200 pounds pre square inch gauge, that are required for certain tubular elements of nuclear reactors. In instances where leakage may occur in tubular elements of a nuclear reactor, it is highly advantageous to be able to test the tubular elements themselves, without having to subject the complete reactor vessel to such hydrotesting. It is an object of the present invention to provide a pipe end sealing element usable for hydrotesting of plain end pipes. It is another object of the present invention to provide a method for hydrotesting of a pipe in a nuclear reactor vessel which utilizes the novel pipe end sealing element. SUMMARY OF THE INVENTION A pipe end sealing element usable in hydrotesting of plain end pipes, such as those present in a nuclear reactor, comprises a cooperative hollow tubular member, hollow conical bushing of variable interior diameter, a sealing plug, and a threaded bolt. The hollow tubular member is adapted to encircle the end of the pipe and has an inwardly directed flange at one end, the flange having a bevelled surface, and a threaded interior wall at the other end. The hollow conical bushing has an inner surface engageable with the pipe outer surface, and an outer bevelled surface complementary to the bevelled surface of the hollow tubular member flange. A slot is preferably provided through the length of the hollow conical bushing to enable decreasing of the interior diameter thereof by forces acting on the outer surface. The sealing plug has a cylindrical portion insertable into the pipe, with a flange portion that rests on the end of the pipe, while the threaded bolt is engageable with the threaded portion of the hollow tubular member. The method of hydrotesting of a pipe, such as a pipe in a nuclear reactor, comprises providing the pipe end sealing element, placing the hollow tubular member over the open end of the pipe, with the threaded portion adjacent and beyond the pipe end, and inserting the hollow conical bushing into the hollow tubular member to surround the outer wall of the pipe. With the bevelled surface of the conical bushing in sliding relationship with the bevelled surface of the tubular element flange, the sealing plug is placed in the pipe with the portion thereof resting on the pipe end wall, and the threaded bolt is engaged with the tubular element threads. By advancing the threaded bolt towards the sealing plug, the hollow tubular member is pulled in an axial direction away from the pipe end, and the conical bushing is decreased in its interior diameter so as to grip the pipe outer wall, by axial sliding along the bevelled surfaces. When the seal is thus effected, a fluid is injected at a predetermined pressure into the other end of the pipe and the fluid resistant capability of the pipe determined.