From our case study archives: St. Lawrence Starch Co., Ltd. operates four distillation columns at their Mississauga, Ontario plant. In operation, a converted starch slurry from the fermenters is fed into the top of the towers. The slurry contains about 10 volume-percent alcohol and 300-350 ppm of chlorides (the source of the stress corrosion cracking). Temperatures range from 150 to 230degF. The four columns have a capacity of 5-million imperial gallons of 193-proof vodka per year.
The oldest column failed by stress-corrosion cracking. Corrosion engineers supplied St. Lawrence with a test rack containing a number of possible upgraded substitutes. As a result, Ferralium® 255 was selected for the new column. Since Ferralium® 255 is more than twice as strong as Alloy 316L stainless steel, the ability to use thinner sections in the construction was an added incentive.
About 4T (9,000lbs) of Ferralium® 255 were used by Dominion Welding and Fabricating, Ltd. in Agincourt, Ontario to make the new column which is nearly 60-ft. high. The 54” diameter shell was rolled from 0.141” thick sheet, 48” x 170”. Tray support rings were supplied as ¼” to 1½” abrasive cut plate which was rolled to the 54” diameter. The handhole flanges were machined from 9” diameter bar stock and the 2:1 semi-elliptical heads were spun. No problems were experienced either in fabricating or welding.
If you would like more information about our Ferralium® 255, please get in touch today.