49 CFR § 178.507 - Standards for plywood drums.
(a) The identification code for a plywood drum is 1D.
(b) Construction requirements for plywood drums are as follows:
(1) The wood used must be well-seasoned, commercially dry and free from any defect likely to lessen the effectiveness of the drum for the purpose intended. A material other than plywood, of at least equivalent strength and durability, may be used for the manufacture of the heads.
(2) At least two-ply plywood must be used for the body and at least three-ply plywood for the heads; the plies must be firmly glued together, with their grains crosswise.
(4) In order to prevent sifting of the contents, lids must be lined with kraft paper or some other equivalent material which must be securely fastened to the lid and extend to the outside along its full circumference.
(5) Maximum capacity of drum: 250 L (66 gallons).
(6) Maximum net mass: 400 kg (882 pounds).