U type Radiant tube: Material:ZGCr25Ni20;ZGCr25Ni35Nb;ZGCr28Ni48W5,or at customers request. ... used as gas burner heater, there're W type, U type, single-ended type, L type,P type. 3. Process:centrifugal and welding flange,elbow4. Material ... : Steel and Heat-treatment: Radiant tubes, and castings of re-heating furnaces, steel mills and heat-treatment industries,etc.