When the National Board of Boiler and Pressure Vessel Inspectors standardized its reporting process for gathering incident statistics in 1991, it was with the objective of creating an accurate and consistent database that would, over time, yield a bona fide method of identifying and correcting the causes of boiler and pressure vessel accidents.
The first composite evaluation of this data, published in 1997, covered a five-year period from 1992 to 1996. With a benchmark in place, the 1997 analysis provided a particularly useful perspective on incident cause and effect. Five years later, it can be stated that the overriding conclusion reached from the second five-year study reinforces the findings of the first: namely, that human error remains the foremost cause of boiler and pressure vessel incidents in North America.