49 CFR 179.200-19 - Reinforcements, when used, and appurtenances not otherwise specified.
(a) All attachments to tank and dome shall be applied by approved means. Rivets if used shall be caulked inside and outside.
(b) Reinforcing pads must be used between external brackets and shells if the attachment welds exceed 6 lineal inches of 1/4-inch fillet or equivalent weld per bracket or bracket leg. When reinforcing pads are used, they must not be less than one-fourth inch in thickness, have each corner rounded to a 1 inch minimum radius, and be attached to the tank by continuous fillet welds except for venting provisions. The ultimate shear strength of the bracket to reinforcing pad weld must not exceed 85 percent of the ultimate shear strength of the reinforcing pad to tank weld.