Moist heat sterilisation (Or steam sterilisation), is the process of using Dry steam in Sterilisation. The condensation of steam into water releases a large amount of energy at the contact point (usually walls of a pipe) causing Sterilisation . This water vapour then acts as a barrier to further condensation on the system surfaces, as such Steam Traps are used to drain water but leave steam in the system. Although moist heat sterilisation does help with Depyrogenation, due to the presence of moisture it does not excel and is not commonly classed as a Depyrogenation process.