178.255-11—Tank mountings.
(a)
Tanks shall be designed and fabricated with mountings to provide a secure base in transit. “Skids” or similar devices shall be deemed to comply with this requirement.
(b)
All tank mountings such as skids, fastenings, brackets, cradles, lifting lugs, etc., intended to carry loadings shall be permanently secured to tanks in accordance with the requirements under which the tanks are fabricated, and shall be designed with a factor of safety of four, and built to withstand loadings in any direction equal to two times the weight of the tanks and attachments when filled to the maximum permissible loaded weight.
(c)
Lifting lugs or side hold-down lugs shall be provided on the tank mountings in a manner suitable for attaching lifting gear and hold-down devices. Lifting lugs and hold-down lugs welded directly to the tank shall be of the pad-eye type. Doubling plates welded to the tank and located at the points of support shall be deemed to comply with this requirement.
(d)
All tank mountings shall be so designed as to prevent the concentration of excessive loads on the tank shell.