VCI and DH anti-corrosion methods have been used for decades for both short or long term preservation. Despite this, many engineers do not understand the nuances of each system. This paper discusses pre-lay up considerations, general guide lines for using each preservation system, examples of typical usage, and the combined use (rarely seen in
specifications). Combined use generally yields the most cost effective protection. Keywords: Dehumidification (DH), mothballing, plant lay-up, sulfur oxides, hydrogen sulfide, chlorine, humidity, vaporizers, emitters, VCI, Volatile Corrosion Inhibitors, contact corrosion inhibitor