Tri-Clamp fittings are the only types of fittings which are approved by 3A organization. 3-A SSI is an independent, not-for-profit corporation dedicated to advancing hygienic equipment design for the food, beverage, and pharmaceutical industries.
The reason these fittings are approved is two-fold:
- Their design minimizes/eliminates the areas where harmful bacteria can harbor and grow.
- They are easy to disassemble and clean allowing.
With regards to 3A certification, it's on a per manufacturer basis. You may be able to purchase tri-clamp fittings from a variety of sources, however, companies that are producing 3A certified products will typically stamp the 3A logo directly on the fittings.
For more information about 3A Organization, you can check out their website here: http://www.3-a.org/