The decision to meet FRA regs was made when the boiler was inspected by a top boiler expert many years ago.
To say the people working on the project for 15 years were not "enlightened' is totaly wrong and tends toward insulting.
Many individuals with diverse experence were (are) involved including those with steam experience. According to the report and subsquent discussions with the consultant, work started to bring the boiler to FRA standards. This included removing the back head stays to get access to the boiler interior for repairs and eventual replacement of the stays. Boiler thickness items were addressed as were other items mentioned in the above posts, work remains incomplete but not insurmountable.