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Ground-Based Cryogenic Leak Test of Fittings for Cryogenic Fluid Management

Mechanically connected fluid joints are virtually unavoidable in complex cryogenic system designs. In the case of spacecraft, the performance of these joints is critical to mission success. This is especially true for long-duration space missions where even very low leak rates can eventually lead to significant propellant losses or failure of vital cryogenic cooling systems. NASA has recently undertaken an effort to quantify the leak rate of Vacuum Coupling Radiation (VCR) fittings over the temperature range from ambient to 20 K, both before and after exposure to a launch vibration profile. A test apparatus employing a cryocooler and a calibrated helium mass spectrometer was developed, validated, and used to obtain quantifiable leak rates at a fitting test pressure of 31 bar (450 psig). Three different fitting sizes were tested, 25.4 mm (¼ inch), 12.7 mm (½ inch), and 6.35 mm (1 inch) and two gasket materials, stainless steel, and silver-plated nickel. Each fitting configuration (size/seal material) was subjected to two consecutive cryogenic thermal cycles/measurement tests, followed by a launch vibration test profile at ambient temperature, and then two additional cryogenic thermal cycles/measurement tests. The design and development of the test apparatus, and test data are presented and discussed in detail.

Document ID
20230009407
Acquisition Source
Kennedy Space Center
Document Type
Conference Paper
Authors
G J Tamasy
(Kennedy Space Center Merritt Island, Florida, United States)
A M Swanger
(Kennedy Space Center Merritt Island, Florida, United States)
J P Sass
(Kennedy Space Center Merritt Island, Florida, United States)
A G Krenn
(Kennedy Space Center Merritt Island, Florida, United States)
W F Reaves
(Noetic Strategies)
Date Acquired
June 23, 2023
Subject Category
Spacecraft Design, Testing and Performance
Spacecraft Propulsion and Power
Meeting Information
Meeting: 25th Joint Cryogenic Engineering Conference and International Cryogenic Materials Conference (CEC/ICMC)
Location: Honolulu, HI
Country: US
Start Date: July 9, 2023
End Date: July 13, 2023
Sponsors: National Aeronautics and Space Administration
Funding Number(s)
CONTRACT_GRANT: 80KSC22CA010
Distribution Limits
Public
Copyright
Public Use Permitted.
Technical Review
NASA Technical Management
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