Page 139 - MY STORY

contained helium at 3,000psi. The pressure vessel

fractured in half ripping through the fully loaded
hydrogen and oxygen propellant tanks. The 25” diameter
pressure vessel failure was traced ultimately to the

migration (diffusion) of hydrogen atoms to a site at the
edge of the circumferential weld that severely embrittled
the metal. This happened 1½ years after manufacture and

after proof testing the pressure vessel at 6,500psi (more
than twice the working pressure at failure). This problem
had never been experienced in the history of titanium

metallurgy.

The problem was traced to the use of the wrong filler
metal used to fill the ½” thick weld joint. The company
that manufactured the pressure vessel had supplied weld
qualification data for this lot of pressure vessels that was

fraudulent. Many pressure vessels from this lot had
already been installed on vehicles, including one on the

launch pad at Cape Canaveral. Fortunately, we were able
to remove all the defective pressure vessels from service
and replace them with properly made ones. The subtle

mechanism(s) that caused the hydrogen to migrate and
embrittle the titanium metal after being in storage for over
a year were utterly unknown. The underlying mechanism

that caused this failure took significant metallurgical