Vessels intended for service under external design
pressures of 15 psi (100 kPa) and less [see U-1(c)(2)(h)]
may be stamped with the Code Symbol denoting compliance
with the rules for external pressure provided all the
applicable rules of this Division are satisfied. When the
Code Symbol is to be applied, the user or his designated
agent shall specify the required maximum allowable external
working pressure.The vessel shall be designed and