Zero-energy determination: Confirmation of vessel and pipeline de-energized state through noninvasive techniques with strain gauges

Abstract

The objective of this research is to identify ways to reliably detect residual material and the associated energy through noninvasive methods using a portable, field-deployable system in order to prevent loss of containment and injury to workers. Leaking valves, defective pressure gauges, and blocked bleeders may cause residual liquid or gas to remain in process equipment, sometimes holding equipment at elevated pressures or allowing a toxic or flammable atmosphere to remain in spite of efforts to clear the equipment. This creates the potential for serious injury to workers when they open, enter, or begin to work on equipment unaware of the hazardous energy still present. The term, “zero energy,” has been used within the context of this research to refer to “a state characterized by the complete absence of hazardous energy.” Hazardous energy is defined as “energy that could cause injury due to the unintended motion, energizing, startup, or release of such stored or residual energy in machinery, equipment, piping, pipelines, or process systems” http://employment.alberta.ca/documents/WHS/WHS-LEG_ohsc_p15.pdf. This research examines a method to determine if a vessel has achieved zero energy, denoted by internal pressure equal to ambient pressure with no residual liquid present, using strain gauges. © 2014 American Institute of Chemical Engineers Process Saf Prog 33: 195–199, 2014