Gas intrusion can be split into two categories: discharge and suction piping. As it relates to discharge piping, gas intrusion can potentially lead to a waterhammer transient. The suction side is much more challenging to define, since more uncertainty is associated with the computational tools currently available in the industry. The uncertainty increases with the system’s complexity when such features as Tee junctions are considered. Gas could be introduced into the piping through multiple methods, including entrainment of air due to formation of a vortex.