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Welding
Figure 4 : Range of Non-Destructive Tests commonly used at Neotiss
Smooth tube External low fin Internal ribs Surface area 1 2 to 3 1,25 Pressure drop 1 1,1 1,4 to 1,8
Heat transfer improvement coefficient
1 1 1,7 to 2,5
Table 1 : Impact of enhancements on surface area , pressure drop and heat transfer coefficient
Also , Neotiss brings its heat transfer expertise to propose the most suited tubes for the customer defined application and specifications .
Production of welded enhanced tubes Example of Neotiss full integrated process for producing such enhanced tubes is illustrated in Figure 3 . The main steps of the fully integrated manufacturing process are detailed on Figure 3 . A series of forming rollers forms the tube which is welded by TIG or laser . Tubes are then annealed and cut . All tubes are 100 % submitted to Non- Destructive Tests ( NDT ) and marked for traceability . Then , low fins and / or internal ribs enhancement are performed by cold forming , so without adding nor removing material . Low fins are created by stacks of discs that are pressed against the external tube surface . Internal ribs are created by a mandrel with spiral grooves that acts on the inner surface of the tube . Heat treatment following the cold forming could be performed to remove the stress induced , for specific applications . A new set of NDT is performed before cutting to final length . Tubes are then deburred , cleaned and inspected before a careful packaging . This process can be subjected to slight variations ( bending , additional tests as well as hydraulic test …) depending on customer requests . Destructive tests , not displayed here , are also realized
according to international standards and customers ’ specification .
Highlight on NDT The Non-Destructive Tests belong to Neotiss ’ DNA , as they guarantee the tubes quality and integrity These tests are detailed on Figure 4 . Eddy current and Ultrasonic testing on bare tubes enable to detect defects such as pores , inclusions , holes , edges mismatches , cracks , lack of welding … whereas leak tests ( air / air , air under water , helium test and hydraulic test ) enable to detect weld stoppage , cracks , holes . High-pressure hydraulic testing also serves as a mechanical integrity test . Eddy current testing on finned tubes allows to detect defects on fin shape or metal inlay . By applying the right Non-Destructive Tests , Neotiss ensures that the quality of the tubes complies with the level required .
About the author
Olivier joined Neotiss SAS in 2019 as Innovation and Development Manager . His background in Material Science and his technical approach allow him to lead development of products and processes . He is also involved in heat transfer expertise to carefully take in account customer needs .
34 Heat Exchanger World March 2025 www . heat-exchanger-world . com