We have engineering calculations done for every insert flange we sell. Due to many of these being 10+ pages for one calculation, we only forward these upon specific request of the customer. Usually, newer engineers who are not familiar with insert flanges like examining these calculations to help understand the process and thinking behind an insert flange. There is no mystery or secret formula behind insert flanges. They are logically formed from the basics of standard flanges and ASME code for flanges. Engineering flange thicknesses for our ASME Conforming line of insert flanges is just flange evolution.