Dear All,
Happened to come across this thread recently which I had previously missed the end of.
Using the excellent link suggested by Caz, I found an article on “Food-Grade” Stainless Steels which may be of interest to some people (attached below).
The article seems to imply (by omission) that none of the grades mentioned in the OP are typically regarded as “Food-Grade”. 
Selection of stainless steels for the food processing industries.pdf 42KB
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i also noticed this useful matrix of some of the grades in use for food applications –
selected SS grades for Food,Beverage Industries.png 111.29KB
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Nonetheless, if one explores the subject a little further, the “Food-Grade” reality is perhaps a little more complex, eg –
(1) Is stainless steel safe?
Stainless steel is one of the most common materials found in kitchens today. It's used in everything from appliances to cookware, dishware, flatware and utensils because it is durable, easy to sanitize and corrosion resistant to various acids found in meats, milk, fruits and vegetables. Most importantly though, stainless steel is a safe option when it comes to use with food and beverage, as there are no chemicals that can migrate into your food from these products
http://mightynest.co...04-188-and-1810
as compared to –
(2) Warning
Despite the fact that T304 is safe to use with foods, you should not store foods or liquids for long periods of time in T304 containers. Although T304 resists rust, the oxygen forming the protective surface with chromium can become depleted during long-term storage, allowing corrosion to occur.
http://www.ehow.com/...ood-grade_.html
And then –
(3) 430
Products made from this food grade generally have less nickel content and a lower resistance to corrosion and temperature. It’s best to dry these containers right after washing.
You may also notice that products will say 18/8, 18/10, 18/0 beside the grade. The first number is the percentage of chromium that is contained in the stainless steel. The second number is the amount of nickel. The higher the numbers, the more rust resistant the product will be. Nickel is safe in small quantities but can provoke a reaction in people with an allergy to it. The average adult consumes between 150 to 250 micrograms of nickel per day. Small doses of chromium, like iron, are good for your health, but can be harmful in higher amounts—50 to 200 micrograms per day is considered safe. One meal prepared with stainless steel equipment (such as stainless steel pots and pans) gives you about 45 micrograms of chromium, according to Health Canada
http://www.canadianf...-safe-for-food/
(4) This forum thread also discusses a few more Food-Grade “possibilities” –
http://www.practical...d-grade-227451/
Rgds / Charles.C