Bimetallic Tubes

Bimetallic Tubes When corrosive requirements or temperature conditions do not permit the use of a single alloy for the tubes, bimetalhc (or duplex) tubes may be used. These can be made from almost anv possible combination of metals. Tube sizes and gauges can be varied. For thin gauges the wall thickness is generally divided equally between the two components. In heavier gauges the more expensive component may comprise from a fifth to a third of the total thickness. 

Bimetallic tubes are available from a small number of tube mills and are manufactured only on special order and in large quantities. 

Clad Tube Sheets Usually tube sheets and other exchanger parts are of a solid metal. Clad or bimetallic tube sheets are usecito reduce costs or because no single metal is satisfactory for the corrosive conditions. The alloy material (e.g., stainless steel, Monel) is generally bonded or clad to a carbon steel backing material. In fixed-tube-sheet construction a copper-alloy-clad tube sheet can be welded to a steel shell, while most copper-alloy tube sheets cannot be welded to steel in a manner acceptable to ASME Code authorities. 

Corrosion resistant performance of steel in both, lead-bismuth coolant and steam-water coolant The technology of fabrication and welding of the bimetallic tubes for steam generators (SGs) that are corrosion resistant in both, lead-bismuth coolant and steam-water coolant Mastered at an industrial scale... 

Tube sheet metal imtsi be selected so that it is suilable fi>r etthcitubc shell side fluid. If this metal can not be (bund, a bimetallic tube sheet has to be used, one side suitable for shell side fluid and the other side suitable for tube ade fluid. If the metal is too expensive, cladding may be required to reduce the cost... 

---