Yes, in User defined - wind pressure vs elevation. Same as for wind. And in your input file do not forget to specify the "Wind shape factor" as the product of CD and DLF (note that CD is 1....1.2 or even bigger, pending on your project specification and DLF typically 1.5....2).

Always remember that 0.3 barg = 3 tons on square meter. Multiplied by CD and DLF you will obtain a pretty nice load on your piping. Check also your supports as it may be not good for blast load.

Best regards,