An Installation Guide for ConFlat Vacuum Flanges
ConFlat flanges and fittings are part of the family of ultra-high vacuum (UHV) components that compress a copper or elastomer gasket between two stainless steel flanges to create a vacuum-tight seal. But, if a tight seal is not maintained, or if it is improperly placed between flanges, UHV pressure will not be maintained.
This ConFlat flange guide will take you through the steps for how to install these flanges onto your system to ensure it runs smoothly and effectively.
Before moving on, wear proper gear, like lint-free gloves when handling any part of vacuum components that eventually encounter any part of the vacuum atmosphere.
Step 1: Cleanliness Examination
Examine both flanges for cleanliness and that sealing surfaces have no dents or scratches. Any damage, in the form of scratches, dings, dents, etc. OR debris, such as dust, lint, dirt, etc. can affect the integrity of the vacuum seal.
Step 2: Flange Compression
The flanges compress the gasket as bolts are tightened; this pressure forces the edges of the two flanges into the gasket, creating an annular groove. Under this pressure, the gasket material cold flows to fill microscopic surface imperfections on the sealing knife-edges. This creates a vacuum-tight seal capable of withstanding extreme temperatures from -328°F to 842°F, with pressures as low as 1X10-13 Torr.
Step 3: Gasket Placement
Each sealing pair of ConFlat flanges typically contains an identical flange face, with a knife-edge machined on the surface. A copper gasket or FKM gasket should be placed against the knife-edge of the non-rotatable flange.
Step 4: Alignment of Bolt Holes and Insert Bolts
Align the bolt holes so the bolts can be fully inserted.
Next, insert bolts and add the washer to the nut within the assembly. All bolts should be hand-tightened.
Step 5: Tighten Bolts
Using a wrench, apply it to both the bolt head and nut. Tighten it by turning the nuts in small increments (1/2 turn or less) using alternating patterns (like changing a car tire). Continue the incremental tightening of the nuts until the desired torque pressures have been achieved.
In short, this is how flanges compress a gasket as fastening bolts are incrementally tightened. The pressure forces the knife-edges into the gasket, creating an annular groove. The gasket material cold flows under the pressure and fills microscopic surface imperfections.