|Fig. 1 - Single rifled boiler tube|
Duplex or composite tubes have been developed to provide a different material on the inside and outside of the tube to meet the requirements of a different environment on either side of the tube. One method of producing a composite tube is by providing a bimetal mother tube before the extrusion or drawing process. Careful development of this process will yield a composite tube with an excellent bond between the two materials.
|Fig. 2 - Finned heat-exchanger tube|
|Fig. 3 - Double-wall leak-detecting tube|
ENGINEERING SELECTION OF PIPE MANUFACTURING METHODS
It therefore is essential that the engineer is aware of the alternates and their operating history of success and failure before an appropriate alternative decision can be accepted. It must also be recognized that choices based on economic considerations alone may prove to be the more costly in the face of the downtime costs of failure.