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Interface Seal. Ground Side. Flight Side. Design Overview. GH 2 Vent Disconnect. STS-116 GUCA Performance. Body Seals. Pre STS-116 and STS-122 and subs. Body Seals. STS-116. Background – Design / Leakage History (Pre-STS-116).
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Interface Seal GroundSide FlightSide Design Overview GH2 Vent Disconnect
STS-116 GUCA Performance Body Seals Pre STS-116 and STS-122 and subs Body Seals STS-116
Background – Design / Leakage History(Pre-STS-116) • STS-116 / ET-123 was first use of new ground umbilical disconnect flight seal design • One-piece seal replaced with flexible two-piece seal to accommodate misalignment during installation • History of leakage with previous disconnect ground side / flight seal design
Historical Changes • Seal Graphic: Flight-Side Seal Configuration(Pre-STS-108 and Post STS-120) STS-116 Flight-Side Seal Redesign
GH2 vent valveremains open in Replenish LH2 IFA STS-116-T-001, Unexpected GH2 Leakage • Background – Loading Phases GH2 unavailable GH2 vent valveclosed GH2 vent valveopen Ground/ETInterface GH2 vent valve GH2 press.line GH2vent line GHe GH2diffuser LH2 LH2 GH2 LH2 • Fast Fill • Tank volume partially filled with LH2 • Ullage gas consists of mixture of GHe / GH2 – GH2 concentration increases as tank is filled • Vent valve opening / closing • Tank pressure: 32.9 – 43.2 psia • Transition to Topping(leakage detected on STS-116) • Valve opens and vents high concentration of GH2 and someLH2 into the vent line • Vent line/umbilical interface exposed to rapid cryo cool-down/press. pulse • Replenish • Steady-state thermal conditions present • No delta pressure at umbilical / tank interface • Less volume / lower concentration of GH2 than during topping phase • Terminal Count • Vent valve closed – GH2 unavailable Critical Environments For Excessive Leakage Not Present During Majority Of Loading Operations