Portable and stationary bulk bins
Primary source
Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
Bulk bins shall be constructed of stainless steel, aluminum or other equally corrosion resistant materials, free from cracks, seams and must have an interior surface that is relatively smooth and easily cleanable. All product contact surfaces shall be easily accessible for cleaning. The capacity of each portable and bulk bin shall be limited to permit proper operating procedures such as sampling and daily removal of all product to preclude commingling of different days production.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.