For short term shutdowns of less than 1 day, especially in warm climates, the vessels can be locked in under full pressure and simply restarted from the point of stoppage. In cold climates or wintertime conditions, 6-12 hours could be a downtime limitation due to more rapid cooling. In such cases, depressurizing or partial depressurizing of the vessels and surrounding piping and equipment would be recommended in order to avoid condensation and liquids during the shutdown. For upstream pipelines and equipment that cannot be depressurized, low point drains should be checked to make sure any collected liquids are drained off before restarting. For long term shutdowns of more than 1 day, it is recommended to regenerate all the beds first, depressurize down to 5-10 psig while maintaining a blanket of dry inert gas in each vessel. Check the vessel pressures periodically in order to maintain positive pressure to avoid air ingress. Note that any beds in a regeneration heating cycle should be completed prior to shutdown in order to avoid repeating the regeneration heating step from the beginning.