Modern petrochemical heat exchangers in AISI 310
Heat exchangers transfer thermal energy in both heating and cooling processes . Due to the wide variety of processes in the chemical and petrochemical industries , knowledge of the materials used in the design of heat exchangers is of paramount interest to fabricators .
By Srikumar Chakraborty - ex ASP / SAIL , freelance consultant
Heat exchangers transfer heat between media , which may be a gas , liquid , or a combination . Fouling undermines heat exchange efficiency . Corrosive fluids associated with intensified fouling may be due to the selection of improper or sub-standard materials , design flaws leading to variable heat transfer , flow resistance degradation , and drops in pressure . When designing the thermal and mechanical properties of heat exchangers , reputable manufacturers consider process characteristics such as fouling rates and the acidic corrosivity of fluids , taking guidance from their R & D team .
Heat exchanger equipment Heat exchangers are widely used in the petrochemical , chemical and refining industries where chemical technology processes ( evaporation , rectification , drying , etc .) are associated with the need for heat supply or removal . Physical properties – High heat transfer coefficient ( requiring high thermal conductivity for tube / pipe material ), as low thermal expansion coefficient as possible considering the materials used for tube / sheet plates , tube support and shell to provide resistance to thermal cycling . Mechanical properties – Good tensile and creep strength properties ( high creep rupture strength at the highest temperature of operation and adequate creep ductility to accommodate localised strain at notches ). Good fatigue , corrosion fatigue and creep-fatigue behaviour . Most austenitic stainless steels with a chromium ( Cr ) content of at least 18 % can be used at temperatures up to 870 ° C , while grades 309 and 310 can tolerate temperatures up to 1150 -1200 ° C . The high fracture toughness and impact strength of grade 310 means it has good resistance to fractures . The low corrosion rate minimises the corrosion allowance required . Grades 309 and 310 also offer corrosion resistance to abnormal chemistry , which may result from upstream leaks or chemistry control failures resulting from a mix-up of shell and tube fluids .
28 Heat Exchanger World February 2024 www . heat-exchanger-world . com