Heat Exchanger, Coil & Radiator Manufacturing worked example

Tube Expansion Time at 7.2% expansion allowance: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop expansion allowance to 7.2%, then walk the calculation through step by step. Estimate adjusted tube expansion time for finned coils and tube bundles from tubes to expand, expansion rate, and allowance.

The inputs for this scenario

  • Tubes to expand: 120 tubes (held at the documented default)
  • Expansion rate: 12 tubes / hr (held at the documented default)
  • Expansion allowance: 7.2 % (the input this scenario stresses; the baseline uses 10)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base tube expansion hours = tubes to expand รท expansion rate.
  • Adjusted tube expansion hours works out to 10.72 hr at these inputs, and this is the headline figure for the scenario.
  • Base expansion hours works out to 10 hr at these inputs.
  • Allowance applied works out to 7.2 % at these inputs.
  • Expansion rate works out to 12 tubes / hr at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where expansion allowance sits at 10% and the headline result is 11 hr, this scenario comes in 2.55% below the baseline at 10.72 hr.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to expansion allowance, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes one steady expansion rate; mixed tube diameters, wall thicknesses or alloys that change cycle time mid-batch are not captured by a single rate.

Results at a glance

  • Adjusted tube expansion hours: 10.72 hr (headline result)
  • Base expansion hours: 10 hr
  • Allowance applied: 7.2 %
  • Expansion rate: 12 tubes / hr

Run it with your numbers

  • To rerun this with your own numbers, open the live Tube Expansion Time calculator, set expansion allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.