Gansu Lanke Petrochemical Equipment (Lanke), has successfully replaced conventional austenitic stainless steel of type 316L (1.4404) in plate air-cooler and plate shell heat exchangers with duplex 2205 (1.4462) from Outokumpu. This application of duplex stainless steel in the plates of these types of heat exchangers, previously considered impossible, was made possible by strong R&D support from Outokumpu. Lanke’s first plate air-cooler heat exchanger using duplex 2205, installed at the Guangzhou Petrochemical Oil Refinery in early 2006, is still in operation after two years from start-up. The operating conditions in oil refinery plate air-cooler and plate shell heat exchangers are characterized by temperatures of up to 140C and 170C respectively and chloride content of hundreds of parts per million (ppm). The engineers wanted to change the plate design to increase heat transfer. Their new design, however, complicated forming, and duplex grades feature only moderate elongation and limited formability compared to austenitic grades. With help from Outokumpu – in the form of information on the metallurgical properties of 2205, samples, examination of test plates, and various tests – Lanke finally developed a new shape, pressing technique, and production route applicable for 2205 sheet, 0.6mm thick, in year 2005. Lanke and Outokumpu are currently investigating possibilities also to use Outokumpu’s duplex grades LDX 2101® (1.4162) and 2304 (1.4362) in plate heat exchangers.
