Safely Purging Tanks, Vessels, and Pipes During Decommissioning and Commissioning

The purpose of this article is to review procedures for purging gaseous content from equipment with an inert substance, so that operations can be performed safely. Concern arises when activities inside equipment requires it to be opened and closed, since both scenarios expose the process substance to air that can lead to potentially dangerous mixtures if concentrations reach a combustible range. Additionally, when toxic substances are present, it is extremely important to safely purge out equipment. Different methods for purging can be used depending on the vessel’s geometry, the vessel’s working pressure, and the purging media and gas relief systems available. The method selected based on the aforementioned factors will lead to different required volumes of purge gas; there is no “one-size-fits-all” action in purging, and each individual case imposes different economics and requirements.