Right from basic needs to more everyday complex necessities stainless steel has become an indispensable part of the production industry as a whole. What makes stainless steel an ideal material is that it is an alloy which is able to cater to the needs of any industry with its mechanical properties, corrosion resistance, or cost.
In the instance of food vs marine industry, there are many factors that need to be taken into account before making a long-term investment in stainless steel equipment. Speaking about the food and beverage industry, the basic requirements would be corrosion resistance, easy to clean, durability and lastly cost. When you think about the food and beverage industry, the number of processing units, the kind of food or liquid, the chemicals present in food or added to food, and the temperature applied to heat or cool the food are just some of the things that come into mind. Every day, various factories produce or process sauces, juices, milk, jams etc, which have different pH values. Prolonged exposure to any type of equipment could lead to cross-contamination along with the product getting spoilt, thus, leading to a huge loss. Moreover, the surface of equipment involved in processing needs to be smooth without any damage to promote ease in the flow of the product. What better than stainless steel to do this! Amongst stainless steel grades, the ideal choice would be between three grades 304, alloy 316 and grade 430. Of all the three grades, alloy 316 is the most expensive, while grade 430 is the least expensive one. However, both grade 304 and 316 are typically used for the manufacture of sanitary products, since they are non-toxic and do not react with the chemicals present in food.
One reason why many food processing industries prefer using grade 430 is because of its very low cost. Grade 430 is an alloy which contains a trace amount of nickel, which explains its lower cost. Furthermore, this alloy not only exhibits strong resistance to nitric & organic acids but also to oxidation. Therefore, as an alloy grade 430 can be used in mildly acidic conditions for a long time. In contrast, grade 304, which is expensive as compared to the former grade is a very popular alloy, not only in the food industry but also in other areas. Often, grade 304 is considered to be an exemplary alloy for the processing of food groups such as meats, milk, fruits and veggies. This is because not only does the alloy prove to discourage contamination by eliminating toxicity, it is easy to clean while being durable. Not forgetting to mention, that by many standards, alloy 304 is considered to be a cost-saving alternative in many industries on account of its long service life and impressive corrosion resistance properties, in relation to food and beverage. On the other hand, grade 316, is the most expensive one of the three and closely follows grade 304 in terms of popularity. While the corrosion resistance and mechanical properties of the alloy are much higher than grade 304, this alloy is used only when suppliers have the need for these properties on a much higher scale.
On the other hand, while speaking about marine grade stainless steel, grade 316 is considered to be the most used one. While grade 316 is suited to on-shore or marine-based applications, it can, however, underperform in terms of resistance to pitting, especially in comparison to many other alloys. For instance, the PREN value of grade 316 is 25, while that of Zeron 100 is 40 with the PREN value of SSC-6MO being high at 48. Moreover, Zeron 100 is characterized by high resistance to stress related corrosion cracking in halide containing environments. Apart from resistance to pitting, austenitic stainless steel grades such as UNS S32750 has a high yield strength of 570 MPa and can perform well down to -50°C. While super austenitic stainless steel grades 6 Mo and SSC-6MO, with their increased molybdenum content, often perform well in marine environments as compared to the conventionally used 300 series and standard duplex stainless steels, while retaining their impressive corrosion resistance and mechanical properties. This being said, both the marine and food industry are demanding sectors, which rely on durable stainless steel for their long term performance. Hence, before choosing the alloy, many of our clients are required to identify the requirements of the application and the product being made in order to make the most of it.