Mich. Comp. Laws § 288.736

Sec. 176. A person shall ensure that all new equipment meets applicable sanitary standards. Equipment and utensils coming in contact with milk, dairy products, mix or frozen desserts, including sanitary pumps, piping, fittings, and connections, shall be constructed of stainless steel or other equally corrosion-resistant material. However, where the use of stainless steel is not practicable, or in old equipment, other metals properly coated or plated may be approved in writing by the director on a case-by-case basis. Nonmetallic parts having product contact surfaces shall be of material that meets sanitary standards.