US Patent 7648732 Coated metal elements for producing glass

The coated noble metal element used in glass manufacture, such as a noble metal pipe, has an uncoated side that contacts a glass melt and an H2-impervious layer or an H2-impervious and O2-impervious layer, which is provided on a side opposite from the uncoated side. The H2-impervious layer or H2-impervious and O2-impervious layer is heat-resistant and is liquid or solid. In one process for providing the layer on the noble metal element an empty space between the noble metal element and a ceramic insulating jacket is filled with a coating material, and then the coating material is melted so that it wets a surface of the noble metal element. The coating material can include glass cullet, crushed glass or glass powder or is a mixture of crushed glass and ground ceramic material.