Tube-Weld High Temperature Sight Window, Quartz

Viewport in refractory metal 253MA for a furnace at 1.5 bar pressure

Encole sight window is designed to operate at 2000°F (1093°C) in an argon-purged furnace. This application cannot use nitrogen because it's only inert at ambient temperature and below 2000°F. At 2000°F nitrogen is chemically active and it will form nitrides, the metal will no longer be stainless. Argon would be a better choice for purging, it's truly inert. 310 stainless can be used, or better yet 253MA.

Commercially available high temperature sight windows: Cyclops Industries' line of high temp sight glasses and viewports