Versus Redesigned SRM Case-To-Nozzle Joint
SRM case-to nozzle joint, which experienced several instances of
O-ring erosion in flight, has been redesigned to satisfy the same
requirements imposed upon the case field joint. Similar to the field
joint, cast-to-nozzle joint modifications have been made in the
metal parts, internal insulation and O-rings. Radial bolts with
Stato-O-Seals were added to minimize the joint sealing gap opening.
The internal insulation was modified to be sealed adhesively, and
third O-ring was included. The third O-ring serves as a dam or wiper
in front of the primary O-ring to prevent the polysulfide adhesive
from being extruded into the primary O-ring groove. It also serves
as a thermal barrier in case the polysulfide adhesive is breached.
The polysulfide adhesive replaces the putty used in the 51-L joint.
Also, an additional leak check port was added to reduce the amount
of trapped air in the joint during the nozzle installation process
and to aid in the leak check procedure.