Putting off the initial inspection (i.e. baseline) of piping and vessels in a new process unit is both common and problematic. The tendency of owners is to rely on the nominal thickness because the actual original thickness was either not measured or not recorded for calculating corrosion rates after the first wave of thickness readings are taken with the equipment having been in service for some period of time. Consequently, significant errors in calculated corrosion rates may result from variations of thickness allowed by mill tolerance standards during fabrication. Not having the original thickness can mask potentially hazardous conditions, or cause concern where none is really warranted. Involvement of the inspection department in a capital project can significantly improve quality, reduce cost, and ensure compliance. The objectives of this paper are to provide: 1) justification for inspection during capital projects; 2) show effective roles for inspection departments in capital projects; 3) justification for performing vendor surveillance in capital projects; and 4) the technical advantages for performing pre-service baseline inspections.
1. The Need for Inspection in Capital Projects
In a recent project involving initial on-stream inspection of four new process units which had been on stream for less than two years we inspected approximately 150 pressure vessels and heat exchangers. Out of these equipment items, we found 22 instances where the wrong thickness of material was utilized during fabrication. A thickness survey at the fabrication facility would have probably prevented these fabrication errors. This discrepancy between the specified equipment and the actual installed equipment highlights the need for inspection as part of the original capital project. In fact, there are several drivers for including inspection in capital projects including regulatory requirements, improved QA/QC, more effective vendor surveillance programs, and more effective budgeting.