In addition to NFPA 52, §8.5, the discharge vent line shall be able to withstand the pressure from the relief vapor discharge when the relief device is in the full open position and shall permit sufficient pressure relief relieving capacity. A spring loaded or counterbalanced rain cap shall be provided on the discharge vent line. The rain cap shall permit the pressure relief device to operate at sufficient relieving capacity.
16 Tex. Admin. Code § 13.187