Tank, Vessel & Pressure Equipment Fabrication worked example

Shell Thickness Allowance with available shell thickness of 310 units: a worked example

What does the result look like when available shell thickness reaches 310 units? The full calculation is worked below with real intermediate numbers. Use it when shell thickness allowance in tank, vessel and pressure equipment fabrication needs a clean margin number for a tank, vessel and pressure equipment fabrication go / no-go review.

The inputs for this scenario

  • Available shell thickness: 310 units (raised for this scenario; the documented default is 125)
  • Code-required minimum thickness: 100 units (unchanged)
  • Reference nominal thickness: 100 units (unchanged)

Working through the calculation

  • Applying the documented formula (Shell Thickness Allowance margin = available value - required value) to the inputs above produces each figure below.
  • At this operating point the engine returns 210 % for margin, the number this scenario is built around.
  • At this operating point the engine returns 210 value for absolute margin.
  • At this operating point the engine returns 310 value for available amount.
  • At this operating point the engine returns 100 value for required amount.

How this compares with the baseline

  • Against the tool's baseline example, where available shell thickness sits at 125 units and the headline result is 25 %, this scenario comes in 740% above the baseline at 210 %.
  • A figure at this level is achievable when available shell thickness is genuinely sustained, not just peaked for a shift. It is a straight thickness comparison and does not itself perform the ASME t = PR/(SE-0.6P) minimum calculation — you must supply a correctly derived required thickness.

Results at a glance

  • Margin: 210 % (headline result)
  • Absolute margin: 210 value
  • Available amount: 310 value
  • Required amount: 100 value

Run it with your numbers

  • Every input above is editable in the live Shell Thickness Allowance calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.