Omnisafe Torque Elimination Fitting Case Studies
- Lawrence Livermore National Labs
- Applied Materials
- NIF Fusion Reactor
- Texas Instruments
- ON Semiconductor
- Several Fabs
1. Lawrence Livermore National Labs
On heated HF lines, the legacy metal face seal fitting without torque elimination loosened during thermal cycling causing HF to leak out of the sniff hole of the female nut. Omnisafe did not loosen during thermal cycling. Omnisafe fittings were opened and retightened every day for 5 years, over 1550 mate/demate cycles before the equipment was decommissioned. The legacy metal face seal fitting without torque elimination had to be replaced every 2-3 weeks since galling of the sealing surfaces disallowed 10-9 leak check.
The Process Module Technology Center (PMTC) is Applied Materials’ flagship 300mm system and process development facility. This facility contains the equipment and processes needed for Applied’s customers to fully develop and pre-test a completely integrated multi-level metal copper interconnect process before delivery. In designing this innovative fab, planners were challenged to look forward and try to envision the facility requirements for the next 4 – 6 generations of cutting edge chip development. Using the International Technology Roadmap for Semiconductors (ITRS 2001) as a guide the Omnisafe torque elimination metal face seal fitting was selected for its superior performance in safety, shock & vibration, and contamination control. The Omnisafe “next generation” fitting is specified globally for all new construction at Applied Materials.
Tritium production system, Lawrence Livermore National Lab, Omnisafe 1/8” fittings, chosen for high integrity seal, multi mate/demate capability.
“Gas Knife” to clean optical surfaces before laser firing, Lawrence Livermore National Lab, Omnisafe 3/8” fittings, chosen due to sealing securely with no galling, no particle shedding into the gas stream.
Here are some of the drivers behind JPL, NASA, Lockheed Martin, Northrop Grumman, and Boeing moving away from the system expense and schedule burden of all welded propulsion systems.
- System modularity, flexibility
- Subsystem or Component test
- Electrical and thermal failures of spacecraft components due to close proximity welding
- Component replacement due to failure or upgrade
- Late component integration
- Cost reduction
- Expedited Schedule
- Weldability, fittings allow purge and inspection of closed loop system welds
The CGA fitting is used to connect a gas cylinder to process lines or analytical equipment. The metal face seal fitting from this CGA to the adjacent pigtail will normally suffer damage to the toroid and not seal after multiple mate/demate cycles. By adding a torque elimination fitting we are able to extend the life of this component dramatically. This fitting is still sealing properly after hundreds of cylinder changes.
Bulkhead Unions attached to the pigtail coming from the process gas cylinder experience rotational torque, loosening, and galling. By eliminating the torque from this fitting the union was made safer, cleaner, and requires less maintenance.
Stainless steel lines supply process gas from a manifold to a flow top. The lines need to be removed so that the chamber can be opened and cleaned periodically. Omnisafe torque elimination was used to prevent damage to the sealing surfaces after multiple tightenings and to prevent the lines from rotating. In the confined space it was possible to tighten the fitting by rotating either male or female nut while holding the other stationary.
Process lines are connected to a component made of a crystal material, if torque is applied to the adjacent union the crystal part will break loose. The Omnisafe fitting prevents this torque, rotation and damage. This application will work equally well for systems containing ceramic or graphite components. The Omnisafe fittings were also used for hazardous process gases, silane and phosphine at this facility.
It was discovered that the connection points between gas assemblies and the facility tubing were particularly susceptible to sealing issues. Omnisafe fittings rectified the sealing issues at these points.
Problems with stainless steel gaskets. Nickel will catalyze reactions or be subject to pitting on process lines containing carbon monoxide, ozone, ammonia, triethyl arsenic and phosphorous compounds. Non-plated stainless steel gaskets are preferred in these applications. Because of severe galling during mate/demate, the stainless steel gasket is difficult to seal in the legacy metal face seal fitting. The Omnisafe fitting can seal with a stainless steel gasket securely with no galling. The Omnisafe fitting is specified where stainless steel gaskets are used and additionally, in connections where the union must be mate/demated multiple times.