Heat Treatment, Furnaces & Thermal Processing worked example

Soak Time Calculator at 12% soak planning safety allowance: a worked example

What does the result look like when soak planning safety allowance reaches 12%? The full calculation is worked below with real intermediate numbers. Use it when heat treat recipes need a quick planning check for soak time at temperature before release.

The inputs for this scenario

  • Section thickness at thickest point: 3 in (unchanged)
  • Soak rate per inch of section: 1.5 in / hr (unchanged)
  • Soak planning safety allowance: 12 % (raised for this scenario; the documented default is 10)

Working through the calculation

  • Applying the documented formula (Base soak hours = soak basis thickness or load units รท soak rate) to the inputs above produces each figure below.
  • At this operating point the engine returns 2.24 hr for required soak time, the number this scenario is built around.
  • At this operating point the engine returns 2 hr for base soak hours.
  • At this operating point the engine returns 12 % for soak allowance applied.
  • At this operating point the engine returns 1.5 in / hr for soak rate.

How this compares with the baseline

  • Against the tool's baseline example, where soak planning safety allowance sits at 10% and the headline result is 2.2 hr, this scenario comes in 1.82% above the baseline at 2.24 hr.
  • A figure at this level is achievable when soak planning safety allowance is genuinely sustained, not just peaked for a shift. The simple thickness-divided-by-rate model assumes a single controlling section and uniform heating; thick non-uniform loads, dense baskets, or low furnace recovery can require longer soaks than the formula predicts.

Results at a glance

  • Required soak time: 2.24 hr (headline result)
  • Base soak hours: 2 hr
  • Soak allowance applied: 12 %
  • Soak rate: 1.5 in / hr

Run it with your numbers

  • Every input above is editable in the live Soak Time Calculator calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.