Stainless steel is a strong steel alloy that is used for production of many steel drums due to its corrosion and impact resistance. It is also easy to clean which makes the metal ideal for many liquid contents. Stainless steel gets it’s famous “stain preventing” powers from the high chromium content, at least 10.5%. The chromium forms a film that prevents surface corrosion by blocking oxygen diffusion to the steel surface and preventing even more damaging corrosion from reaching the metal’s internal structure. It’s this bond between the steel and the oxide ions that gives stainless steel it’s unique properties.
Not all stainless steel is made the same, however. There are over 60 different grades of stainless steel. Each one has its own unique properties and microstructure that make it valuable. Skolnik utilizes 3 types of stainless for steel drums; 316, 304, and 409. 316 is the strongest stainless steel and considered surgical steel. This is mostly used for the pharmaceutical industry that desires the strongest protection and high sanitation requirements. 304 is a middle grade stainless steel, or food grade. By regulations, nitric acid should be stored in a 304 grade barrel, but the grade is also commonly used for wine, beer, and spirits. Finally, 409 is a weaker grade, but still offers more protection than a standard or galvanized carbon drum. Because its so easy to clean, stainless steel lends itself to reusability. Depending on the condition, a drum should be able to be used much more than once which increases the value of the drum and hence, makes stainless steel a popular material.
With so many valuable qualities it’s easy to ask “why isn’t everything stainless steel?” There are some contents regularly stored or transported in drums that are not safe to use in stainless. Some chemical makeups react negatively to the microstructure of stainless steel and can cause damage to either the drum or the contents themselves. Before storing anything in a stainless steel drum you should check for compatibility. If contents are safe for stainless go one step further and verify which grade is the most cost effective material while still keeping safety the number one priority. That little extra chromium might be all it takes to make sure your contents arrive safely to their destination.