Corrosion of Stainless Steel in Food and Beverage

Lead In Photo Corrosion

The customer, a global producer of food and beverage products, contacted Central States Industrial (CSI) with a problem stating "we are facing frequent leaking issues with the existing 316L stainless steel piping, bends, and other fittings." CSI was able to analyze the failure and determine its cause. This particular application ran UHT juices (ultra high temperature processed fruit juice) through their lines and were experiencing corrosion pits and chloride induced stress corrosion cracking. On exposure to such an environment, the acting protective, passive layer of the stainless steel was damaged, resulting in pits, referenced as leaks. These pits led to the formation of cracks. On close observation, it was found that these cracks were not in the vicinity of the welds but were from the base metal adjacent to the welds. Cracking is a characteristic of stress corrosion cracking.

After finding the root cause, CSI was able to supply all the necessary tube and fittings in AL-6XN, which is the most effective super austenitic 6% molybdenum alloy. The molybdenum contained in 316L (2.5%) is marginal in chloride containing environments at elevated temperatures. AL-6XN has increased levels of molybdenum (6.2%) appropriate for such environments and consequently, AL-6XN was found to be more resistant to both pitting corrosion and chloride induced stress corrosion cracking.

As a result, the customer has no longer experienced material failures where they are using the alloys supplied by CSI. This has resulted in millions of dollars in savings.