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Corrosion
Plate of the heat exchanger under maintenance .
preferred to minimize the risk of crevice corrosion .
• Optimized plate design : engineering plate configurations that minimize crevice dimensions and allow for improved fluid circulation can mitigate the risk of crevice corrosion .
• Regular maintenance : periodic disassembly , cleaning , and inspection of the heat exchanger to eliminate accumulated deposits and detect early signs of crevice corrosion are essential for longterm reliability .
Galvanic corrosion Galvanic corrosion in plate heat exchangers is a result of the contact between dissimilar metals in the presence of an electrolyte , leading to accelerated corrosion of the less noble metal . The multiple metal plates in plate heat exchangers make them susceptible to galvanic corrosion if the compatibility of materials is not carefully considered during the design phase . Mitigation strategies :
• Material compatibility : selecting materials with similar electrochemical properties minimizes the potential for galvanic corrosion . This includes using plates made from the same or compatible alloys .
• Dielectric insulation : introducing dielectric materials or coatings between dissimilar metals can prevent direct electrical contact , reducing the likelihood of galvanic corrosion .
• Electrochemical protection : implementing cathodic protection techniques , such as sacrificial anodes or impressed current systems , can help mitigate galvanic corrosion by providing a more sacrificial source for the corrosive attack .
Shell-and-tube heat exchangers Shell-and-tube heat exchangers are widely used in industries such as oil and gas , chemical processing , and power generation due to their versatility and ability to handle high-pressure and hightemperature applications . However , they are also prone to corrosion , particularly in the tube bundle where the process fluid comes into direct contact with the metal surface . Common types of corrosion in shell-and-tube heat exchangers include erosion-corrosion , which occurs when the metal surface is simultaneously subjected to fluid flow and corrosion , leading to accelerated material loss .
Erosion-corrosion Erosion-corrosion is a prevalent form of degradation in shell-and-tube heat exchangers , particularly in high-flow areas where the metal surface is simultaneously exposed to fluid flow and corrosive environments . This dual-action mechanism results in accelerated material loss and can compromise the structural integrity of the tubes . Contributing factors :
• High flow rates : rapid fluid flow can lead to increased turbulence , causing mechanical wear on the tube surfaces and exposing them to corrosive agents .
• Particulate matter : the presence of abrasive particles in the fluid can exacerbate erosion-corrosion , as these particles can act as abrasive agents , accelerating the deterioration of the metal surfaces .
• Chemical composition : corrosive substances in the process fluid , such as acids or alkalis , can www . heat-exchanger-world . com Heat Exchanger World December 2024
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