Corrosion Behaviour of Steels in Nigerian Food Processing Environments|
Ofoegbu, Stanley Udochukwu; Ofoegbu, Pearl Ugochi; Neife, Simeon I. & Boniface A., Okorie
The corrosion of mild steel (uncoated), galvanized steel and stainless steel (304L) have been studied using the weight loss method over a period of 98 days with measurements made at 14 days’ interval in ground melon (locally called egusi), cassava pulp, mashed palm fruit, tomato pulp, and black-eyed bean pulp respectively. The results obtained show that the average corrosion rates of 304 stainless steel, galvanized steel and mild steel are in ground melon (1.98 x 10-3, 1.81 x 10-2, 2.65 x 10-2) mpy; in cassava pulp (3.68 x 10-3, 7.09 x 10-1 , 5.64 x 10-1) mpy; in mashed palm-fruit (4.75 x 10-3, 2.38 x 10-1, 2.83 x10-3) mpy ; in bean pulp (3.07 x 10-3, 9.25 x 10-1, 1.16) mpy; and in tomato pulp (5.46 x 10-3, 6.99 x 10-1, 7.83 x 10-2) mpy respectively. Normalizing these corrosion rates data with respect to that of stainless steel in each environment showed that in ground melon galvanized steel and mild steel had corrosion rates 91.41 and 13.38 times that of stainless steel; in cassava pulp 183.68 and 148.11 times; in mashed palm-fruit 50.08 and 58.58 times; in bean pulp 301.3 and 377.85 times; and in tomato pulp 128.2 and 14.34 times respectively. Presentation of the average corrosion rate and average specific weight loss of mild steel and galvanized steel, relative to that of stainless steel enables an easier assessment of the corrosion resistance of these substitute steels, which is envisaged will be of immense benefit to the local food and quality regulatory agencies and food processing equipment fabricators. It is our desire that these results provide the scientific community with a relatively long term corrosion data on Nigerian food processing media.