Since the current equipment and system equipment are designed and manufactured according to the original processing of domestic low-sulfur crude oil, the equipment has poor adaptability, and the growth of imported crude oil has brought about comprehensive corrosion of equipment and systems. Especially for heat exchange equipment, in order to ensure its long-term safe operation, it is urgent to develop some new corrosion-resistant materials for the manufacture of heat exchanger tube bundles.
In order to meet the needs of petrochemical enterprises, 08Cr2AlMo seamless steel pipe, based on 12Cr2AlMoV, has jointly developed a new type of 08Cr2AlMo heat exchanger special seamless steel pipe with high resistance to H2S-H2O system and H2S-HCl-H2O system stress corrosion cracking, and resistance to high-temperature sulfur corrosion and dilute organic acid corrosion. The new steel retains the content of corrosion-resistant elements Cr, Al, and Mo in chemical composition, reduces the C content of steel, and eliminates the V content. This not only maintains corrosion resistance but also ensures that the hardness of the steel pipe matches the hardness of 16Mn forgings commonly used in oil refining equipment, ensuring good expansion performance. The steel was subjected to H2S stress corrosion resistance test, HCl aqueous solution corrosion test, and water quality corrosion test. The test results show that its corrosion resistance is significantly better than the commonly used pipe 10.
08Cr2AlMo steel is used as a heat exchange tube. The commonly used specifications are 19 by 2 and diameter 25 by 2.5. It uses cold-drawn tubes and is finally normalized at 940 degrees + annealed at 700 degrees. Its grain structure is ferrite + pearlite, the grain size is 8, and the non-metallic inclusions are much less than 1.5. 08Cr2AlMo steel also has good high-temperature mechanical properties. This steel has passed the review and certification of the National Pressure Vessel Standardization Technical Committee and the State Technical Supervision Bureau, and passed the results appraisal organized by the Jiangsu Provincial Science and Technology Commission at the end of 1999. The price of 08Cr2AlMo steel pipe has obvious advantages over stainless steel, and its corrosion resistance is better than stainless steel in an environment containing Cl ions, so its application and development prospects are broad. Since 1999, it has been used in Shanghai Refinery, Nanjing Refinery, Maoming Petrochemical Refinery, Jinling Petrochemical Refinery, Urumqi Petrochemical Company and other units.

Tube bundle manufacturing process
When manufacturing the 08Cr2AlMo heat exchanger tube bundle, the following measures were taken: fillet welds were used for tube head welding, and the tubes extended 305mm from the end face of the tube sheet to prevent the tube ends from burning; welding process assessment tests were conducted with reference to the 08Cr2AlMo welding performance report of Hefei General Institute; automatic argon arc welding was used for tube head welding, with a preheating temperature of 150 degrees before welding and a post-heat treatment temperature of 250 degrees for 1.5h. After welding, the tube head was subjected to stress relief heat treatment at 670 degrees; the hardness of the tube head weld was controlled to be no more than 220HB; after heat treatment, the tube head was expanded to eliminate gap corrosion; the expansion rate was controlled; the tube head was 100% PT after expansion. After the pressure test, no leakage was found in the pipe head of the tube bundle, indicating that the pipe head has beautiful appearance and excellent internal quality.

Cherry
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Email: Cherry@jinyoumetal.com
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