49 CFR §178.510

1. (a)The following are identification codes for wooden barrels:
   1. (1)2C1 for a bung type wooden barrel; and
   2. (2)2C2 for a slack type (removable head) wooden barrel.
2. (b)Construction requirements for wooden barrels are as follows:
   1. (1)The wood used must be of good quality, straight-grained, well-seasoned and free from knots, bark, rotten wood, sapwood or other defects likely to lessen the effectiveness of the barrel for the purpose intended.
   2. (2)The body and heads must be of a design appropriate to the capacity and intended use of the barrel.
   3. (3)Staves and heads must be sawn or cleft with the grain so that no annual ring extends over more than half the thickness of a stave or head.
   4. (4)Barrel hoops must be of steel or iron of good quality. The hoops of 2C2 barrels may be of a suitable hardwood.
   5. (5)For wooden barrels 2C1, the diameter of the bung-hole may not exceed half the width of the stave in which it is placed.
   6. (6)For wooden barrels 2C2, heads must fit tightly into crozes.
   7. (7)Maximum capacity of barrel: 250 L (66 gallons).
   8. (8)Maximum net mass: 400 kg (882 pounds).