One of the more common inspection monitoring programs for pressure vessels is to perform thickness measurement at Corrosion Monitoring Locations (CMLs) to allow monitoring of minimum thicknesses and provide estimates for corrosion rates. These minimum thicknesses and corrosion rates are critical in supporting risk based inspection techniques or in setting half-life prescriptive re-inspection intervals. I have previously documented the problems that can arise when performing thickness monitoring for piping in a series of articles published in Inspectioneering Journal from 2012-2013 1,2,3,4,5. It has been the author's experience when reviewing plant inspection data for pressure vessels in preparation for risk based inspection assessments that the quality of thickness data and corrosion rates for pressure vessels is often as much of a concern as piping thickness data. This article will outline the common pitfalls associated with the pressure vessel thickness monitoring process and provide recommendations on correcting these.
展开▼
