Guided walkthrough of the API 653 §5 decision tree (Figure 5-1)
◉ API 653 §5 STYLE CHECK · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. This walks the exact branching logic of Figure 5-1, traced directly from the standard's flowchart image (not just the summary text) and cross-checked against §5.3.1–5.3.11. The Figure 5-2 exemption curve (shell metal temperature vs. thickness) is only given as a graph in the source, with no formula — the "approximate reading" shown at that step is a piecewise-linear digitization of a well-gridded curve, offered as a helper, not an authoritative answer; you still confirm that step yourself. API 650 Figure 2.1 (a separate exemption curve for listed steels) isn't available here at all, so that step is always a manual judgment call. This tool doesn't replace a fracture mechanics analysis or an authorized inspector's assessment.
Identification
Research entries stay private to you for practice/testing. Switch to Official once this is a real assessment your company should see.
Shell Data (optional — auto-answers steps 4 & 5 below)
Shell metal temperature: for unheated tanks, use the design metal temperature per API 650 §2.2.9.3. Leave membrane stress blank to answer that step manually.