Methodological aspects of assessment of the strength and residual service life of pressurized vessels based on acoustic-emission diagnostics

The state-of-the-art in acoustic-emission diagnostics of pressurized vessels is analyzed. It is shown that the widely used qualitative relationship between nondestructive testing methods and the science of material strength can be replaced with a quantitative relationship based on specially organized non-destructive testing procedures carried out when the object being tested is operated. Based on a number of examples, in which the state of pressurized vessels subject to low-temperature hydrogen (hydrogen sulfide) corrosion and to pitting corrosion is assessed, the main concepts and options of the suggested methods are described. Results of the assessment of the residual service life of some vessels are presented. The conducted research shows that a new regulatory framework needs to be developed for assessing the operability of expensive equipment in oil-refining and petrochemical plants on the basis of acoustic-emission diagnostics, applied fracture mechanics, and risk analysis.