August 18, 2016 – Welders have completed the final plug fusion welds on NASA’s Space Launch System (SLS) liquid hydrogen tank at the Michoud Assembly facility in New Orleans. The liquid hydrogen tank, a liquid oxygen tank, four RS-25 engines and other elements form SLS’s core stage, which also serves as the rocket’s structural backbone.
To create a qualification test article, like the one shown here, six 22-foot-tall barrels and two domed caps are welded together. Using frictional heating and forging pressure, friction stir welding produces high-strength bonds virtually free of defects. The process transforms metals from a solid state into a “plastic-like” state and uses a rotating pin tool to soften, stir and forge a bond between two metal sections to form a uniform welded joint.
At the beginning and end of each weld, holes remain where the rotating pin tool enters and exits the metal. Welders plug the holes after the tank is assembled.
The qualification test articles closely replicate flight hardware and are built using identical processing procedures.
When it’s completed, SLS will be the most powerful rocket in the world. It will be used to launch the Lockheed Martin-built Orion spacecraft into deep space.