E. Jones, Bureau Veritas Asset Integrity and Reliability Services Pty Ltd
M. Cooper, Santos Ltd
In 2011, a pilot program of Non-intrusive Inspections was conducted, covering a total of eight vessels in the Moomba gas processing plant and in surrounding field areas.
The opportunity for Non-intrusive Inspection (NII) was brought about, at least in part, by the widespread implementation of Risk-based Inspection in Santos.
Previously major outages were driven by prescriptive requirements for internal inspections of pressure vessels every four years (for most vessels). After Risk-based Inspection was implemented, the internal inspection intervals were extended for many vessels, but there were a few remaining items still requiring internal inspection every four years. In particular, flare drums required shorter inspection intervals due to the greater variability in their service conditions and the modelled corrosion rates. Therefore the driver for Nonintrusive Inspection was to avoid costly plant shutdowns which were otherwise driven by a very few, or in some cases, a single vessel. This made Non-intrusive Inspection a cost effective option.