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Bay Tank Fabricates RA333® Alloy Calciner Units(ASTM SB-718, UNS N06333) One of the first steps in the processing of kaolin clay is the thermal process known as calcining. This high temperature process requires a temperature of approximately 927 degrees C (1700 degrees F) to cause certain chemical reactions and phase changes to occur e.g., dehydration, calcination of calcium carbonate (CaCO3), and perhaps oxidation of certain ferrous iron and other organic matter.
One major producer of kaolin recently selected RA333 as the alloy of construction for three new kaolin clay calciner units. RA333 was selected because of its excellent high temperature (to 2200 degrees F) oxidation resistance and strength and outstanding thermal show and fatigue resistance. This service is severe from an oxidation standpoint and the RA333 alloy is the latest alloy upgrade, in this case, over RA330 which was serviceable but tended to fatigue and oxidize over time in the areas just above the burners. Bay Tank and Fabricating Company, Inc. of Panama City, FL is the ASME code shop which was selected to fabricate the three calciner units in RA333 alloy. Even though RA333 is not a common alloy of construction at Bay Tank, they maintain the proficiency needed to fabricate all high performance engineering alloys. They were able to handle the RA333 alloy fabrication in stride, using standard fabrication practice and equipment. Bay Tank constructed these calciner units with shell plate of 3/8" thick RA333 alloy. The shell seam was welded over an internal skeletal structure of RA333 square bar, using RA333-70-16 AC/DC titania electrodes. Bay Tank opted to use SMA welding (covered electrodes) over the faster sub-arc process in order to keep heat input low. Although it was not required, Bay Tank elected to x-ray the welds after the cap pass was applied to assure full penetration, crack free welds. Shearing and rolling of the RA333 alloy was achieved with standard equipment without difficulty. The quote the Bay Tank spokesman, "The alloy formed and rolled like 304 stainless steel. We even rolled the square bar on our plate roller! The RA333 patterns and smaller pieces we cut with plasma." RA333 alloy is a nickel based super alloy with outstanding resistance to high temperature oxidation and carburization. This grade has exceptional ability to withstand thermal cycling and shock and can withstand corrosive environments from room temperature to a white heat. This 45% nickel, 25% chromium alloy gets its name from its unique 3% molybdenum, 3% cobalt, 3% tungsten addition. Other applications include dampers, thermowells, flare tips, molten glass process equipment, radiant tubes and various kilns. RA333 is a registered trademark of Rolled Alloys, Inc. |
Bay Tank & Fabricating Co. Inc. 1810 Industrial Drive Panama City, Florida 32405 Mailing address: P.O. Drawer 2418 Panama City, Florida 32402 Phone: +1 (850) 763-7696 Fax: +1 (850) 785-1051 Email: info@baytankfab.com CYber SYtes, Inc. Web SYtes by Design |