ASME B31.3 Process Piping Wall Thickness & Span Calculator (Excel Dashboard)

Description
Built on the ASME B31.3 Lorenz equation, t = PD / 2(SEW + PY), for process piping wall-thickness verification. Three KPI cards give the verdict first: wall thickness PASS/FAIL, governing max support span, and external collapse pressure rating.
The usual B31.3 headache is allowable stress — it sits in the copyrighted Appendix A tables that no calculator may reprint. This tool solves it honestly: it auto-calculates Basic Allowable Stress from your pipe grade's public SMYS and tensile strength, using the general rule B31.3 itself states (lesser of UTS/3 or 2/3 SMYS). You get a defensible ambient/moderate-temperature value with zero lookup, plus a manual override cell for creep-range service or an exact Appendix A value.
Y coefficient and weld strength reduction factor W are dropdowns per Table 304.1.1, with manual override. Corrosion allowance and mill tolerance are included in the required thickness.
How to use:
1. Enter design pressure, inside diameter, trial wall thickness, corrosion allowance and mill tolerance in the blue input cells (bar, mm, %).
2. Pick the pipe grade, weld joint type and the material/temperature category for Y.
3. Read the three KPI cards. The calculation trail underneath shows allowable stress, pressure design thickness, required nominal thickness and margin, so a checker can follow it line by line.
Every formula is native, readable Excel — no macros, no hidden hardcoded numbers. Built as a fast, transparent second check during FEED or detailed design, not a replacement for final sign-off by a qualified engineer. Not affiliated with or endorsed by ASME.