PSA 6.3 — Compressors & Turbines: NEMA SM-23, API 617/612, and the Combined Check That Bites
Here is the criterion that governs steam-turbine piping worldwide, written the way the standard writes it:
3F + M ≤ 500·D_e F is a force in pounds. M is a moment in foot-pounds. They are added together. There is no term that makes the units agree, no radius, no section property — just a linear combination of two quantities of different dimension, compared against a constant times a pipe size in inches.
Commit to an answer before reading on: is that a mistake, or is it doing something a dimensionally correct formula could not?
It is not a mistake, and…
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