If your using Stainless Steel for Brining look for 316 grade Stainless. Although more expensive than the alternative (430) the higher Nickel content is the difference in both performance and cost. If you are unsure of the grade of stainless check it with a magnet. 430 grade is ferritic and will react to the magnet.
The following is a description I grabbed online
Grade 304 is mentioned but it is not "food grade"
Grade 316 stainless is an austenitic stainless steel alloy with a high chromium and nickel content. Like many steel alloys, it has a continuous use temperature several times higher than most food making processes will ever require (more than 800°C, or 1472°F).
What makes the grade 316 alloy an ideal food grade steel sheet material is the fact that it has a high resistance to acids, alkalis, and chlorides (such as salt). Other austenitic stainless steels, such as grade 304 SS, can experience severe pitting corrosion when exposed to salt, which is often present in food products.
316 makes for great food grade stainless steel containers for nearly any food application.