FEMTC 2024 in Kansas City, MO and online | Sept 18-20.



Thunderhead Engineering completed a project for the American Petroleum Institute to evaluate the relative strengths of the roof-to-shell and shell-to-floor joints.

Look carefully, and you will see oil storage tanks all around us. Obviously, if for some reason (lightning strikes for instance) a combustible gas mixture in the tank is ignited and a deflagration occurs, we want to ensure that the pressure is relieved in a controlled manner and the contents of the tank remain intact. This can be accomplished by following design guidelines in American Petroleum Institute Standard 650 which can be used to ensure that the roof-to-shell joint is frangible and that the roof will detach from the tank if over-pressurized.

Links to download the report and software developed as part of this project are given below. Also, the Welding Research Council Bulletin 410 (ISSN 0043-2326) contains a summary of this work.


SafeRoof v2.1
SafeRoof Manual
Zhi Lu Thesis
Report (FEB 2005)


The original research is documented in Zhi Lu's Thesis entitled "EVALUATION OF DESIGN CRITERIA FOR STORAGE TANKS WITH FRANGIBLE ROOF JOINTS".

This video documents the testing done to understand frangible joint failure.


This research was sponsored by the American Petroleum Institute, but neither the American Petroleum Institute, nor Thunderhead Engineering, nor Kansas State University, nor any of the authors make any claims or warranty with respect to the software, manuals, or reports.