Pressure vessel having groups of welding nipples alternately arranged

Claim 1

A PRESSURE VESSEL COMPRISING A WALL MEANS ADAPTED TO SUSTAIN A PRESSURE DIFFERENTIAL THEREACROSS, A PLURALITY OF CLOSELY SPACED OPENINGS FORMED THROUGH SAID WALL, A PLURALITY OF TUBULAR NIPPLES ARRANGED IN ALIGNMENT ONE WITH EACH OPENING, SAID OPENINGS BEING SO CLOSELY SPACED THAT THE LENGTH OF THE NIPPLES PROJECTING FROM THE SURFACE OF SAID WALL WOULD SUBSTANTIALLY PRECLUDE WELDING THE JOINT BETWEEN SAID WALL SURFACE AND SAID NIPPLE IF ADJACENT NIPPLES WERE SUBSTANTIALLY CO-EXTENSIVE FROM THE SAME SURFACE OF SAID WALL, SAID NIPPLES COMPRISING A FIRST GROUP OF ALTERNATE NIPPLES ASSOCIATED WITH ALTERNATE OPENINGS AND PROJECTING FROM ONE SURFACE OF SAID WALL AND TERMINATING SUBSTANTIALLY FLUSH WITH THE OPPOSITE SURFACE OF SAID WALL, AND A SECOND GROUP OF INTERMEDIATE NIPPLES DISPOSED BETWEEN SAID ALTERNATE NIPPLES AND PROJECTING FROM SAID OPPOSITE SURFACE OF SAID WALL AND TERMINATING SUBSTANTIALLY FLUSH WITH SAID FIRST SURFACE OF SAID WALL, AND WELDS CONNECTING THE PROJECTING PORTIONS OF SAID NIPPLES TO THE ADJACENT WALL SURFACE.