The recognized international codes, such as ASME , API, BS provide design and fabrication guidelines for various equipment used in industries viz. pressure vessels, piping and storage tanks. However, the fabrication standards do not address acceptability of the equipment on detection of any deterioration; once put in to the operation.
The engineering assessment becomes essential when flaws such as “leakage”, ‘metal loss’ or ‘linear indications’ are detected during routine inspections. Sometimes, observed damages or flaws, do not meet the definition criteria as per assessment steps given in the international standards of fitness for service. In order to asses such damages, a structured engineering approach based on experience and judgment would help in such situations.
Describing the structured engineering assessment approach, this paper discusses a case study on typical ‘hydrogenation reactor’ that displayed micro-level leakage. Until 2015, the reactor often leaked during service prior to the assessment. This approach using various NDT methods, microstructural examination and structured engineering analysis identified the problem of dilution of base metal with welding that was leading to inter dendritic corrosion at micro level. The structured engineering analysis paved the forward path by which the reactor could be operated without any unscheduled outages since then after providing improved welding procedure.