Branched pipe joint having a tube connecting plug

Claim 1

MEANS FOR MECHANICALLY CONNECTING A BRANCH TUBE IN ANGULAR RELATION TO A MAIN TUBE FROM AN OPENING IN THE WALL OF THE LATTER HAVING DIMENSIONS SUCH THAT ITS PERIPHERY IS IN CONTACT WITH THE OUTSIDE WALL OF THE BRANCH TUBE, SAID MEANS COMPRISING A RELATIVELY ELONGATED PLUG INSERTED THROUGH SUCH OPENING AND HAVING AN INNER END SHAPED FOR RIGID UNTWISTABLE SURFACE TO SURFACE CONNECTION WITH THE WALL OF THE MAIN TUBE OPPOSITE SUCH OPENING; MEANS RIGIDLY CONNECTING SAID INNER END TO THE WALL OPPOSITE SAID OPENING IN SURFACE TO SURFACE ENGAGEMENT WITH SAID WALL; SAID PLUG INCLUDING A LEAD-IN SECTION OF SUBSTANTIALLY CONSTANT CROSS-SECTION EXTENDING THROUGH SUCH OPENING, IN UNIFORMLY SPACED RELATION TO THE PERIPHERY OF THE OPENING, FOR TELESCOPING ENGAGEMENT IN THE BRANCH TUBE, AND A TUBE EXPANDING SECTION OF SAID PLUG EXTENDING INWARDLY FROM THE INNER END OF SAID LEAD-IN SECTION AND PROGRESSIVELY INCREASING IN CROSS-SECTIONAL AREA FROM A POINT AT THE INNER SURFACE OF THE WALL HAVING THE OPENING THEREIN TOWARD THE INNER END OF SAID PLUG, TO EXPAND, WITHIN THE MAIN TUBE AND BEGINNING AT SUCH POINT, THE INNER END OF A BRANCH TUBE TELESCOPED OVER SAID LEAD-IN SECTION AND MOVED INWARDLY THROUGH SUCH OPENING AND ALONG SAID EXPANDING SECTION; THE UNIFORM PERIPHERAL SPACING OF THE LEAD-IN SECTION AND THE WALL OPENING BEING SUBSTANTIALLY EQUAL TO THE WALL THICKNESS OF THE BRANCH TUBE.