The product range

To cover both the standard and high performance requirements of the UHV community we offer two material grades as standard in our product range. With 304 and 316LN Stainless Steels it is possible to cover the operational temperature range of -190°C to +450°C. This can be extended (when using vacuum firing) to +950°C with our Standard 316LN grade of flange material.

All flanges are manufactured in dedicated CNC machining cells to ensure excellent product consistency. Every stage of production is carefully quality controlled with full traceability and each flange is code stamped with a cast number. Each flange is processed through an automated aqueous cleaning procedure and individually sealed and packed so that the product is in perfect condition for use on UHV equipment.

304 Stainless Steel (FC and FCR Series).

All FC and FCR series flanges are manufactured from specially selected steel of high cleanliness, with carefully controlled chemistry (304 stainless steel in lower range of carbon content). This ensures that chromium depletion of the heat affected zone which can lead to inter-granular corrosion (due to the formation of chromium carbides) is avoided after welding.

The flange material undergoes specialised (both multi-axial and axial) forging processes. This produces the best material microstructure by breaking up inclusions and improving the grain structure and texture to minimise any porosity and associated leakage problems. The flange material is then solution-treated to stress-relieve the material and restore original properties of the steel. Micro-cleanliness, hardness, inclusion count and magnetic permeability are all checked prior to supply.

316LN Stainless Steel (FCL and FCRL Series).

316LN flanges are specially produced for more demanding applications including the need for higher hardness (at high temperatures) and low magnetic permeability. This grade of austenitic stainless steel has nitrogen added as a strengthening agent, increasing overall hardness and strength. Hardness value of 316LN is typically 160-180 Brinell and generally higher than 304 series steels. More importantly, 316LN retains the hardness at elevated temperatures, especially after repeated bakeouts, or high temperature system degassing procedures.

The 316LN steel is Electroslag refined (ESR) to eliminate gross macro segregation and grain inhomogeneity resulting in an excellent uniform structure. The ESR process also substantially reduces the total inclusion content and removes impurities, producing a very clean material. This minimises any risk of leakage paths due to inclusions. 316LN steel produced by this route is virtually ferrite-free and flanges produced from this material have a very low magnetic permeability (<1.005).

The flange material is also forged using a specialised multi-axial and axial forging process, to eliminate and porosity and leakage problems. It is subsequently solution-treated to stress-relieve and restore the original properties. The steel characteristics are checked prior to supply. Each flange is tamped to indicate the steel grade and cast number for full traceability. This high specification steel, together with a combination of carefully controlled chemistry, ESR and forging processes. produces the ultimate material for UHV flanges.

Material Comparison 304 and 316LN