Custom Flange-Mounted Radiant Tubes | OEM Manufacturing | FH® Alloy FH® Alloy manufactures I-shaped radiant tubes for industrial furnaces and heat treatment equipment, providing customized solutions for indirect heating systems used in various thermal processing applications. Compared with bent or U-shaped designs, the I-shaped radiant tube features a straight-through structure that is suitable for furnace systems requiring simple installation, convenient maintenance, and