10 CFR § 71.61 - Special requirements for Type B packages containing more than 105A2.
A Type B package containing more than 10 5A2 must be designed so that its undamaged containment system can withstand an external water pressure of 2 MPa (290 psi) for a period of not less than 1 hour without collapse, buckling, or inleakage of water.
[69 FR 3795, Jan. 26, 2004]