Structural weld leak testing in support of the international space station Node 1, airlock, and laboratory flight elements

摘要

Developmental testing on the detector probe method of helium leak detection was performed in support of the International Space Station program (ISS) at Marshall Space Flight Center (MSFC), in Huntsville AL. The test evaluated detector probe sniffing techniques, head designs, optimum sizes and linear head speeds used to detect a known leak approximately 1E-4 accs helium. The test resulted in detector probe head design and fabrication for leak testing pressurized vessel external surfaces, and also in the developement of the detector probe head design and test procedure used to test all structural welds on Node 1, Airlock, and Laboratory flight elements. In support of the ISS structural weld leak test, a helium mixing test was performed to evaluate the helium mixing method required to obtain a uniform helium concentration during testing of these modules, as a known helium concentration is necessary to accurately determine leak rates. Testing was performed in a 2500 cubic foot pressure vessel located at MSFC. Mixing fans were positioned internal to the pressure vessel, and oxygen sensors were mounted in the vessel top, middle and bottom areas in order to evaluate helium concentrations. The vessel was pressurized to 14.7 psig with 100