»
Event review
Heat exchangers in demanding applications
Of special interest to our Heat Exchanger World readers , we spoke with Angela Philipp , Technical Marketing Specialist at Alleima , after her presentation about the advantages and disadvantages of using duplex stainless steel for heat exchangers in demanding applications . “ Duplexes combine the best properties of austenitic stainless steels and carbon steel , and in general , perform very well in process conditions where you may expect pitting , crevice corrosion , localised corrosion and stress corrosion cracking ( SCC ),” Angela explains . “ Indeed , the materials were first developed to combat these types of corrosion mechanisms . Carbon steel has good resistance to SCC , but performs poorly in tough corrosive environments . In many cases , duplex outperforms austenitic stainless steels in terms of pitting corrosion in the temperature range of -50 ° C up to 250 ° C . For process conditions outside of this temperature range , highly alloyed austenitic stainless steels are a better choice as they have a very good corrosion resistance for pitting and SCC .” Angela went on to explain that , for some applications , duplex stainless steels are the ideal heat exchanger material because they combine very good corrosion resistance with significant design advantages . For example , both welding during fabrication and the process conditions , cause thermal expansion in heat exchangers , which can lead to corrosion problems . Duplex stainless steels have a thermal expansion close to that of carbon steel , giving them definite design advantages over austenitic stainless steels . Angela continues : “ Duplexes also have very high strength , around double the strength of standard austenitic stainless . This is particularly advantageous for larger equipment and parts , as it makes it possible to reduce the wall thickness of the equipment , resulting in significant weight and cost savings as less material is required . There is no need to allow extra thickness to achieve corrosion resistance ; for example , a heat exchanger constructed with a 3mm carbon steel wall could potentially be replaced with a 2.11 mm or even thinner duplex heat exchanger , depending on the process conditions .” Angela concludes that , typically , duplex heat exchangers have a longer equipment life and require less maintenance , especially in comparison to carbon steel . “ An additional advantage compared to standard austenitic stainless steel is that if there is an unexpected change in process conditions , for example , dirty cooling water creates more chlorides in the water , then duplex will perform much better .”
The KCI Editorial team in conversation with Angela Philipp of Alleima .
Green Steel World Conference and Expo 2023 were proudly sponsored by :
www . heat-exchanger-world . com Heat Exchanger World May 2023
35