49 CFR § 178.518 - Standards for woven plastic bags.
(a) The following are identification codes for woven plastic bags:
(1) 5H1 for an unlined or non-coated woven plastic bag;
(2) 5H2 for a sift-proof woven plastic bag; and
(3) 5H3 for a water-resistant woven plastic bag.
(b) Construction requirements for woven plastic fabric bags are as follows:
(1) Bags must be made from stretched tapes or monofilaments of a suitable plastic material. The strength of the material used and the construction of the bag must be appropriate to the capacity and intended use of the bag.
(2) If the fabric is woven flat, the bags must be made by sewing or some other method ensuring closure of the bottom and one side. If the fabric is tubular, the bag must be closed by sewing, weaving, or some other equally strong method of closure.
(3) Bags, sift-proof, 5H2 must be made sift-proof by appropriate means such as use of paper or a plastic film bonded to the inner surface of the bag or one or more separate inner liners made of paper or plastic material.
(4) Bags, water-resistant, 5H3: To prevent the entry of moisture, the bag must be made waterproof by appropriate means, such as separate inner liners of water-resistant paper (e.g., waxed kraft paper, double-tarred kraft paper or plastic-coated kraft paper), or plastic film bonded to the inner or outer surface of the bag, or one or more inner plastic liners.
(5) Maximum net mass: 50 kg (110 pounds).