Machines, apparatus, plant, components and ancillary equipment used to seal, isolate, or contain extreme environments, in particular furnaces, ovens or similar machines or cryogenic, vacuum, nuclear, radioactive, toxic, corrosive, flammable of explosive environments; vacuum components, fittings and fabrications; pumps; valves; glass to metal seals, glass encapsulated vacuum gauge heads, viewing windows; glass and ceramic feeding troughs; glass vacuum vessels and fittings; parts and fittings f...