Process equipment in hydrocarbon services shall be subjected to periodic inspections and maintenance which may result in the pressure containment being broken. Such breaks in the pressure containment

can result in explosive mixtures of air and hydrocarbon vapour being present. Therefore whenever pressure containment is broken measure must be taken to ensure that:

• An explosive atmosphere is not present during such times that work is being undertaken
• An explosive atmosphere is not present in the equipment prior to its return to hydrocarbon service
• Pressure containment is tested and confirmed before the equipment is returned to hydrocarbon service

Nitrogen Purging and inerting process vessels, equipment, pipeline, piping system are two common, yet distinctive practices to control the concentration of oxygen, thereby reducing not only fire, explosion hazard but to preserve the system for longer duration.