* taken at the point indicated by the red arrow on the first S.E.M.s
After checking the nickel peaks on the bottom EDS we notice much higher nickel reading.
This higher signal is from nickel particles that are embedded into the torroid of the gland from the galled nickel gasket during tightening of the fitting.
This reading is consistent and confirms the conclusions from the previous particle study and S.E.M.s
Flight Qualified – Multi Mate/Demate – Metal Face Seal Fitting Global Observer – hydrogen powered, fuel system, UAV MSL Mars Rover – launch 2011, for the liquid Freon heat rejection system, Omnisafe 3/8” fittings JPL DAWN – Xenon Ion Propulsion, Asteroid Belt, Oct 2007, Omnisafe 1/8” fittings NASA Evolutionary Xenon Thruster (NEXT) Program –…
These findings are in regard to 22 nm circuitry, which is currently in design for 2011-2012. For this circuitry we will be concerned with all particles >10nm. There are some new issues that may reveal a need for cleaner, torque elimination metal face seal fittings. One new challenge is that with these extremely small geometries,…
Multi Mate-Demate Record This report details a Multi mate/demate field study at Lawrence Livermore National Laboratory. Over six years in service, this fitting was mate/demated 1557 times and was still working effectively when decommissioned. This evaluation shows the direct cost savings by avoiding the replacement of fittings that no longer passed leak check in this…
Stainless steel gaskets are required in certain gas systems such as carbon monoxide, ozone, and trimethyl arsenic. Because SS gaskets are harder than nickel, the torque induced problems of sealing and galling are amplified. Due to the SS sealing problems, some companies have specified silver plated SS gaskets to reduce friction and galling. Recently these…
In the S.E.M. (top) the severe effects from over tightening on the sealing surfaces of a legacy face seal fitting are shown. In the S.E.M. (lower) using Omnisafe torque elimination, the seal area is not galled. One half turn past finger tight is a worst case scenario. At 5/8 turn past finger tight the gasket…
This is the equipment and procedure used to determine the quantity and size of the particles shed into the process stream, due to galling, as a legacy metal face seal fitting is tightened. Objectives Compare standard metal face seal fitting with the OmniSafe torque suppression fitting over the following criteria: Examine the sealing surfaces of…
