Segmented back-up bar

Claim 1

A BACK-UP BAR FOR USE INTERRNALLY AT ABUTTING ENDS OF TUBULAR MEMBERS WHILE SAID MEMBERS ARE BEING WELDED TOGETHER AND ADAPTED TO BE EASILY REMOVED AFTER THE WELDING OPERATION, COMPRISING: (A) A PLURALITY OF ARCUATE SHORT BACK-UP BAR SEGMENTS, JOINED END-TO-END TO FORM A CONTINUOUS RING; (B) EACH SAID BACK-UP SEGMENT COMPRISING; (1) AN ELONGATED RIGID FRAME MEMBER HAVING AN OUTER CHANNEL RECESS; (2) AN INFLATABLE BLADDER AT THE BOTTOM OF THE RECESS OF SAID RIGID FRAME MEMBER; (3) A RESILIENT, FLEXIBLE RIBBON MEMBER SUPPORTED UPON SAID INFLATABLE BLADDER, AND (4) A PLURALITY OF ELONGATED CONTIGUOUS CONTACT SURFACE PLATES FORMING THE BACK-UP CONNTACT SURFACE FOR SAID SEGMENT; (5) EACH SAID CONTACT SURFACE PLATE BEING TRANSVERSELY ALIGNED TO SAID RIBBON MEMBER AND SECURED THERETO WHEREBY THE CONTACT SURFACE FOR SAID SEGMENT WILL BE LONGITUDINALLY EXTENDING FLEXIBLE AND ALSO YIELDABLE TO MAINTAIN THE BACKUP BAR TIGHTLY AGAINST THE INTERNAL SURFACE OF SAID TUBULAR MEMBERS AT OPPOSITE SIDES OF THEIR ABUTTING EDGES.