A tank must have a cross section design that is--
(a) Circular; or
(b) Other than circular and stress analyzed experimentally by the method contained in UG-101 of the ASME Code. [CGD 73-172, 39 FR 22950, June 25, 1974, as amended by CGD 84-043, 55 FR 37410, Sept. 11, 1990]