If you refer to API 650, Appendix A. Go to table A-4b, it allows you to have a 3/16" shell course for a 30 ft diameter 1 shell course tank. Also refer to API 650 3.6.1.1. This refers you to smallest nominal plate thickness for a given diameter
I am an API inspector. I am trying to figure out the proper way of determining Tmin for a bottom head or cone shape of the bottom of an atmoshepheric storage tank. These tanks are supported in the air and a bottom head or come has a nozzle or nozzles coming out. The top head is open and there...