The sign accompanying the display. It reads
First Stage Y-Ring
The size of the propellant tanks in the Saturn V's first stage made the
fabrication hugely difficult. Hardest of all was welding the tank domes and
vertical walls without creating thick "lap joints" (where pieces overlap).
MSFC designed an aluminum "Y-ring" to join the domes and walls of the
first-stage propellant tanks. The part of the Y-ring that curved inward
connected to the dome. The straight side was welded to both the tank wall and
the outer skin of the rocket.
On display are two slices of Y-ring material. Note their Y shape. The sample above demonstrates how the Y-ring
attached to the tank wall and rocket skin.