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MOTOROLA INC. Technical Developments Volume 16 August 1992
VACUUM FITTING MODIFICATION INCREASES SAFEl-Y LEVEL IN LPCVD SYSTEMS AND REDUCES EXPENSIVE DOWNTIME
by Tim Warfield and Emmett Howard
The addition of a stainless steel ring to a commonly- used gas fitting increases the safety of the use of these fittings in hazardous gas applications in LPCVD processes.
The stainless steel ring prevents the two finished mating surfaces from contacting each other in the absence of the crush washer. In this way the fitting is ensured of an obvious and leaky connection in the absence of a crush washer. The absence of the crush washer is easily detected and can then be added. The sealing surfaces will also be undamaged and will not have to be replaced.
In a wide percentage of applications at least one. of the fittings is welded into the equipment. The removal of the damaged fitting necessitates a trip to the machine shop and the piece of process equipment is down until the piece is returned.
In the worst scenario an attempt is made to use the damaged fittings. The usual result is an extended period of leak detecting attempts and in the worst case can lead to a buildup of hazardous gas within the fitting or equip- ment enclosure.
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