Section 154.438 - Design vapor pressure(a) If the surface of an independent tank type A are mostly flat surfaces, the Po must not exceed 69 kPa gauge (10 psig).(b) If the surfaces of an independent tank type A are formed by bodies of revolution, the design calculation of the Po must be specially approved by the Commandant (CG-ENG).CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983; USCG-2014-0688, 79 FR 58284, Sept. 29, 2014